The Natural Environment & Health in Africa A review of the impacts of biodiversity loss and environmental degradation on human and animal health, and recommendations for frontline action The Natural Environment and Health in Africa Abstract Much of recent human development has come at the expense of Nature — undermining ecosystems, fragmenting habitats, reducing biodiversity, and increasing our exposure and vulnerability to emerging diseases. For example, as we push deeper into tropical forests, and convert more land to agriculture and human settlements, the rate at which people encounter new pathogens that may trigger the next public health, social and economic crisis, is likely to increase. Expanding and strengthening our understanding of the links between nature and human health is especially important in Africa, where nature brings economic prosperity and wellbeing to more than a billion people. Pandemics such as COVID are just one of a growing number of health challenges that humanity is facing as a result of our one-sided and frequently destructive relationship with nature. This report aims to inform professionals and decision-makers on how health outcomes emerge from human interactions with the natural world and identify how efforts to preserve the natural environment and sustainably manage natural resources could have an impact on human and animal health. While the report focuses on the African continent, it will also be of relevance to other areas of the world facing similar environmental pressures. Key Words NATURE, NATURAL ENVIRONMENT, BIODIVERSITY, ONE HEALTH, PLANETARY HEALTH, AFRICA, SUSTAINABLE DEVELOPMENT, CONSERVATION, HEALTH, ECOSYSTEM SERVICES, DISEASE EMERGENCE, ZOONOSES DOI: https://doi.org/10.5479/10088/111281 © 2021 Smithsonian Institution Non-commercial uses are allowed. Commercial rights are reserved; for commercial permissions, please contact: rightsmanager@si.edu. Suggested citation Hassell, J.M., Bukachi, S.A., Muloi, D.M., Takahashi, E., Franklinos, L.H.V. The Natural Environment and Health in Africa, Smithsonian Institution, (2021), https://doi.org/ 10.5479/10088/111281 The Natural Environment and Health in Africa Acknowledgments WWF and the Smithsonian are grateful for USA), Adam Ferguson (Field Museum of Natural generous financial support received from The History, USA), Eric Fèvre (Institute of Infection, Rockefeller Foundation, with which this report Veterinary and Ecological Sciences, University of was produced. Liverpool, UK), Dipankar Ghose (WWF, India), Barbara Haesler (Pathobiology and Population Sciences, Royal Veterinary College, UK), Ilka Herbinger (WWF, Germany), May Hokan (WWF, Germany), Tabitha Kimani (Food and Agricultural Organisation of the United Nations (FAO), The Gambia), Duncan Kimuyu (Karatina University, Kenya), Richard Kock (Pathobiology and Population Sciences, Royal Veterinary College, UK), Melissa Leach (Institute of Development Studies, UK), Suzan Murray (Global Health Program, Smithsonian Institution, USA), Kris Lead Authors Murray (MRC Unit The Gambia at LSHTM), Joshua Onono (School of Public Health, University of Nairobi, Kenya), Okechukwu Idumah Okogwu (Department of James Hassell (Global Health Program, Smithsonian Applied Biology, Ebonyi State University, Nigeria), Institution, USA and Epidemiology of Microbial Tequiero Abuom Okumu (School of Veterinary Disease, Yale School of Public Health, USA) Medicine, University of Nairobi, Kenya), Steven Lydia Franklinos (Centre for Biodiversity and Osofsky (Cornell University College of Veterinary Environment Research, University College London, Medicine, USA), Kevin Queenan (Pathobiology and UK) Population Sciences, Royal Veterinary College, UK), Alice Ruhweza (WWF Regional Office for Africa, Co-authors Kenya), Lian Thomas (International Livestock Research Institute, Kenya), Hannah Wild (Department of Surgery, Salome Bukachi (Institute of Anthropology, Gender University of Washington Medical Center, USA), Arne and African Studies, University of Nairobi, Nairobi, Witt (Centre for Agriculture and Bioscience Kenya), Dishon Muloi (International Livestock Research International (CABI), Kenya), Jeff Worden (WWF Institute, Nairobi, Kenya), Emi Takahashi (Médecins Regional Office for Africa, Kenya), Katherine Worsley- Sans Frontières, Geneva, Switzerland). Tonks (Global Health Program, Smithsonian Institution, USA). Contributors Tendai Chinho (WWF Regional Office for Africa, Zimbabwe), Darcy Ogada (The Peregrine Fund, Kenya); Peregrine Rothman Ostrow (Institute of Infection, Veterinary and Ecological Sciences, University of Liverpool, UK), Peter Scheren (WWF Regional Office for Africa, Kenya), Francesca Vitali (Global Health Program, Smithsonian Institution, USA), Dawn Zimmerman (Global Health Program, Smithsonian Institution, USA). Expert Reviewers Bassirou Bonfoh (Centre Suisse de Recherches Scientifiques en Côte d'Ivoire, Côte d’Ivoire), Thomas Breuer (WWF, Germany) Sarah Cleaveland (Institute of Biodiversity Animal Health & Comparative Medicine, University of Glasgow, UK), Benis Egoh (Department of Earth System Science, University of California Irvine, The Natural Environment and Health in Africa Contents Contents .……………..……………………….…………………………………………1 Forewords .……………..……………………….…………………………………………2 Glossary .……………..……………………….…………………………………………5 Executive Summary .……………..……………………….…………………………………………6 Introduction .……………..……………………….…………………………………………8 SECTION 1: Mapping the impacts of environmental degradation on health in Africa ………………………13 Health in Africa as a system ………………………14 How are efforts to understand the links between the natural environment and health distributed across African? ………………………18 SECTION 2: The impacts of environmental protection and biodiversity conservation efforts on health ………………………20 Protection of critical biodiversity areas ………………………21 Box 1: Land use induced spillover and ecological stress ………………………23 Box 2: Translocations, conservation and health ………………………24 Box 3: Control measures at the wildlife-livestock-human interface ………………………25 Promoting sustainably managed landscapes ………………………26 Box 4: Impact of organic chemicals on fisheries ………………………28 Box 5: Human-wildlife conflict and poisoning ………………………29 Box 6: Gender, wild meat value chains and zoonotic spillover ………………………30 Box 7: The impact if invasive species on health ………………………31 Climate change adaptation and mitigation ………………………32 Box 8: One Health, climate and armed conflict in Africa ………………………34 Nature positive finance ………………………35 Box 9: Natural capital accounting in Africa ………………………37 Greening development ………………………38 Box 10: Rapid urban development, ecology and health ………………………39 An engaged society ………………………40 Box 11: Participatory approaches to engage and empower communities in addressing linkages between the natural environment, conservation and their health ………………………41 SECTION 3: Key challenges and recommendations for applying One Health to address environmental and health crises in Africa ………………………42 Challenge 1: Lack of evidence for the mechanisms linking the natural environment to human and animal health ………………………43 Challenge 1: Absence of metrics and indicators with which to measure and value the impact of the natural environment on health ………………………47 Challenge 3: Loss of awareness and knowledge across African society for the deep connections between the natural environment and human health ………………………49 Challenge 4: The connections between natural environment and health are rarely factored into public health or sustainable development policy in Africa ………………………51 Bibliography .……………..……………………….………………………………………..53 Appendix .……………..……………………….………………………………………..62 1 The Natural Environment and Health in Africa Foreword by the Director of WWF Africa As the world strives to recover from the COVID-19 pandemic, the sense of urgency has never been greater to understand the complex connections between the environment, animal, and human health. Preventing zoonotic disease spillover is critical for safeguarding nature and protecting human health. COVID-19 illustrates the dire threats posed from zoonotic diseases and highlights nature’s role in protecting human health, wealth, and wellbeing. Understanding more about nature’s role in supporting animal and human health in Africa is at the heart of this report. It highlights the inextricable links between natural health and human health. It also underscores the urgent need for more research into the costs of Secondly, nature’s broader role in supporting environmental degradation to our health and the health remains undervalued. We are paying a benefits of investing in nature as a form of high price for the degradation of Africa’s natural preventative medicine. capital. Boosting our understanding of the links between Thirdly, the health risks posed by environmental nature and human health is especially important degradation cause disproportionate harm to in Africa, where nature brings economic Africa’s poorest and most rural populations, who prosperity and wellbeing to more than a billion live in closest association with biodiversity and people across a biodiverse continent rich in natural ecosystems. natural resources. Fourthly, we need to educate everyone better We know that animals and humans pay a high about the bond between human, animal, and price for environmental degradation and environmental health. biodiversity loss. Last year we not only had the outbreak of COVID-19 but two Ebola outbreaks in Fifthly, the connections between nature and the Democratic Republic of the Congo (DRC), health are rarely factored into sustainable and Nigeria’s most severe Lassa fever outbreak development policy or public health policy in on record. Most of East Africa is predicted to see Africa. We ignore the importance of nature, at our a 20% increase in risk of schistosomiasis - a peril. water-borne disease - over the next 20 to 50 years due to climate change. We need to talk more. To research more. To measure more. We need greater awareness. We This report highlights five key priorities to pay need more evidence. We need new partnerships. attention to. We need better policies. Firstly, we know too little about the dangers of From pollution, poverty, pathogens and pesticides environmental degradation to human health. We to parasites and pandemics, the links between need to plug those gaps in our knowledge. animal health, human health, and environmental health are evident everywhere. 2 The Natural Environment and Health in Africa The close connection between human health, environmental health and animal health is encapsulated in the concept of One Health. By creating the One Health High-Level Expert Council to “collect, distribute and publicize reliable scientific information on the links between human, animal and environmental health” global organizations are moving in the right direction. Governments, academic institutions, non- governmental organizations, and civil society must form broad partnerships to address evidence gaps, deliver evidence to policymakers, and engage with and educate the public on the importance of the natural world to health. This report would not have been a success if not for the Smithsonian Conservation Biology Institute’s Global Health Program (GHP), the University of Nairobi (UoN), the International Livestock Research Institute (ILRI), University College London (UCL) and the World Wide Fund for Nature (WWF). Prevention is better than cure. And less costly too. Harnessing the power of nature to protect health is not only smart. It is the path to long-term sustainability and our own survival. ALICE RUHWEZA Africa Regional Director WWF International PG-ENDS-30.7.2021 3 The Natural Environment and Health in Africa Foreword by the Deputy Director of the Smithsonian Conservation Biology Institute It is a pleasure to introduce this report that has been prepared by scientists from the Smithsonian Conservation Biology Institute’s Global Health Program (GHP), the University of Nairobi (UoN), the International Livestock Research Institute (ILRI), and University College London (UCL) in collaboration with the World Wildlife Fund (WWF). The ongoing COVID pandemic, like many of its predecessors, lays bare the grave implications that our environmental footprint on this planet has for human health. Pandemics, though, are just one of a growing number of health challenges that humanity is facing as a result of how we interact with nature. Because of this, breaking down disciplinary barriers between those working on science and policy in the health and environmental sectors (who may not be familiar with the interdependence between nature and health) is crucial to address the root cause of emerging health issues. By providing a high-level overview of how efforts to conserve environmental change and biodiversity loss species and their habitats, and reverse whose livelihoods and health are at greatest risk. environmental degradation, can impact human Bridging the gap between these communities and animal health, and thus highlighting the and public health and environmental policy impact of existing efforts to protect our planet, makers, through the support of public health this report aims to do just that. programs and alternative livelihoods, is highlighted as a priority for biodiversity However, fostering collaboration between those conservation and securing global health. It is working in natural resource management, important to remember that the challenges sustainable development and public health is outlined in this report are not unique to the Africa only the first step towards addressing these continent, and many pose a global threat to problems. Efforts to develop effective strategies human and animal health. As such, what is and policy frameworks that achieve desired learned by mobilizing resources to expand health outcomes for humans and animals scientific enquiry, raise awareness and develop through the sustainable management of solutions that promote healthy and resilient ecosystems, must be guided by a clear people and ecosystems in Africa, can readily be understanding of the processes that link human applied to other parts of the world. and animal health to the environment through people’s actions. With this in mind, the report WILLIAM PITT highlights critical knowledge gaps and makes a Deputy Director series of recommendations that should help Smithsonian Conservation Biology Institute define research priorities moving forward. Recommendations also include the need to engage the private sector, governments, and the citizens that they represent. As we often see when practicing biodiversity conservation, it is the communities who live at the forefront of 4 The Natural Environment and Health in Africa Nature based solutions: Actions that protect, manage and restore natural and modified Glossary ecosystems to address societal challenges and enhance human wellbeing. Natural Capital: Elements of the natural environment that provide benefits for humans Antimicrobial resistance (AMR): Microbial including ecosystems, species, freshwater, land, resistance to antimicrobials is a natural minerals, the air and oceans. phenomenon but is exacerbated by their inappropriate use in human and animal medicine. Non-communicable diseases: Non-infectious AMR arises when disease-causing organisms diseases that tend to be of long duration and are evolve to become resistant and survive the the result of a combination of genetic, medicines used to treat them. physiological, environmental, and behavioural factors. Anrothopozoonosis: Disease caused by pathogens that have a natural reservoir in humans Pathogen: Disease-causing organism which and are transmitted to animals. include viruses, bacteria, fungi, helminths (worms) and protozoa. Biosecurity: Prevention of the introduction and spread of pathogens to minimize the risk of Planetary health: An inter-disciplinary approach transmission of infectious disease. that addresses the interconnections between the processes of environmental change and their Comorbidity: The presence of one or more impacts on human health and well-being, at additional health conditions often co-occurring scale. This approach builds on the ecological with a primary health condition. framing of planetary boundaries and supports the UN Sustainable Development Goals and the Paris Disability-adjusted Life Years (DALYs): A Climate Change Agreement. measure of human disease burden, expressed as the number of years lost due to ill-health, disability Pathogen spillover: The process by which a or early death. pathogen is transmitted from a reservoir host species to a novel host species. Host: An organism that can be infected by an infectious agent under natural conditions. Reservoir host: A host in which an infectious agent can be maintained and from which Ecological resilience: The capacity of an infection is transmitted to a target population. ecosystem to absorb repeated disturbances or shocks and adapt to change without Sylvo-pastoralism: A practice of integrating fundamentally switching to an alternative stable trees, forage, and the grazing of domesticated state. animals in a mutually beneficial way.infection is transmitted to a target population. Ecological stressor: A physical factor (i.e., loss of nutrients, pollution, heat, drought) that has an Vector: An organism, typically invertebrate, adverse impact on an ecosystem or its biotic acting as intermediary in the transmission of an components. In living organisms this may reduce infectious agent from a reservoir to a target survival or growth or reproduction. population e.g., tick, mosquito. Ecosystem services: The benefits provided to Water-energy-food (WEF) nexus: The study of humans by natural systems that range from food the connections between the water, energy, and and water to recreation and climate food resource sectors, together with the regulation.growth or reproduction. synergies, conflicts and trade-offs that arise from how they are managed. Immunotoxicity: Adverse effects on the functioning of the immune system that results from Zoonosis: Disease that can be transmitted exposure to toxic substances. between humans and animals.-offs that arise from how they are managed. Invasive alien species (IAS): Alien or non-native species that become invasive and have Zoonotic pathogen: Pathogen that is maintained detrimental ecological, social and economic in a non-human animal reservoir and is capable effects. of infecting and causing disease in humans. The Natural Environment and Health in Africa Executive Summary Unsustainable exploitation of natural resources transformation, is increasing and poses a including deforestation, agricultural and urban potentially severe threat to public health expansion, and climate change has led to on the African continent. dramatic environmental change. In Africa, health impacts in humans and animals are an There is evidence to suggest that the protection increasingly apparent outcome that can arise as and sustainable management of natural a consequence of severe and wide-ranging resources and biodiversity can support and environmental degradation. The concurrent improve health, but in many cases, this remains emergence of COVID-19, Ebola virus disease anecdotal and not backed up by data. outbreaks in DRC and Lassa fever in Nigeria has raised awareness of the potential links between 2. Scientific evidence for the mechanisms environmental change and human health. One linking environmental degradation to Health has emerged as a framework for identifying, assessing, and strengthening the human and animal health is weak. links between the health of humans and animals, and the natural and anthropological systems Major gaps exist in our understanding of the from which health outcomes arise. mechanisms by which environmental degradation endangers human health. For This report presents an evidence-based review example, despite the World Health Organization of the threat that environmental degradation recognizing that habitat fragmentation and poses to health in Africa, and the ways in which biodiversity loss endangers human and animal these threats could be addressed through the health, very few studies are dedicated to protection, sustainable management and use of measuring this relationship. Without concrete natural resources and biodiversity. This evidence scientific evidence, measures required to prevent is used to identify the most pressing challenges national, regional and global health crises cannot that must be overcome to ensure that the natural be designed and tested in confidence. environment is appropriately valued for the role it plays in supporting health on the African 3. Metrics and indicators are required to continent. value and monitor the impact of the natural environment on health. The reports aim is to inform those working in the environment and public health sectors of the While the economics of pandemic prevention connections between environmental degradation have been laid out by scientists, nature’s and health, while highlighting the limitations that broader role in supporting health remains weak evidence, lack of metrics, and educational undervalued. We found that the economic gaps pose to achieving desired health outcomes losses that ecosystem degradation caused for humans and animals through the sustainable through infectious disease, nutritional disorders management of ecosystems. In this sense, it is and mental illness are not being measured. To intended as a starting point for concerted, multi- address this, new metrics and indicators are sectoral efforts to address these limitations. required to reliably quantify and can be used to monitor the benefits of healthy, biodiverse ecosystems on human health, similar to those Its key messages are as follows: that have been developed for ecosystem service valuation and “natural capital” accounting. 1. Environmental degradation stemming from rapid urbanization, increased 4. With support, African society is in a expansion and intensification of strong position to raise global awareness agriculture, and ongoing economic 6 The Natural Environment and Health in Africa for the connections between the natural embrace the role of the natural environment in environment and human health. determining health outcomes. Much of African society possesses strong 6. Policy needs to put evidence into historical connections to the natural practice. environment. This should be fostered through advocacy, education, professional training The connections between environmental and community engagement efforts that link degradation and health are rarely factored ecosystem and human health. Since health into sustainable development policy or public risks cause disproportionate harm to Africa’s health policy on the African continent. poorest and most rural populations, engagement Platforms are required by which evidence linking of rural communities who rely on natural the natural environment to human health can be ecosystems for their wellbeing and livelihoods to effectively presented to policy makers and used support them in protecting ecosystem to test and scale interventions that frame natural functioning for their health, is an important way resource management as a form of preventative to communicate and mitigate risk. This can be medicine. achieved through leveraging indigenous knowledge and providing incentives for social For these challenges to be addressed, a multi- and behavioural change. sectoral, coordinated effort is required to gather concrete data on the drivers of animal and 5. Interdisciplinary partnerships are human health in Africa’s natural landscapes, required to develop, test and scale health while practically testing and demonstrating interventions informed by the natural effective solutions to improve conservation and environment. health outcomes. Since health outcomes emerge at broad scales across land and seascapes, Connections between the natural world and there is an urgent need for small-scale initiatives human health are poorly represented in to be connected and integrated into broader, educational and advocacy frameworks. intersectoral One Health initiatives that involve Advocacy should be used as a tool by which to governmental, academic, non-governmental link people’s health with their environment organizations and civil society. Such initiatives through experience and practice, inspiring the are required to ensure that the natural next generation of African leaders and policy environment is at the centre of public health makers. Educational institutions and academic policy, while engaging with and educating the networks practicing One Health also need to public on the importance of the natural world to health. Camels in the Afar Region of northern Ethiopia The Natural Environment and Health in Africa Introduction Systems that support human and animal life rely increasing contact between people, domestic on a healthy natural environment and yet “natural animals, and wildlife 3,8. Climate change further systems are being degraded to an extent impacts human health by promoting climate- unprecedented in human history” 1. sensitive diseases such as those transmitted by Unsustainable exploitation of natural resources insect vectors (e.g., mosquitoes, ticks) 9, or has led to dramatic environmental change indirectly via effects on biodiversity 8 and human including deforestation, agricultural and urban vulnerability to disease (e.g., nutrition, poverty) expansion and climate change. Sub-optimal 10. Furthermore, the disruption of natural systems health is an increasingly apparent outcome from also generates burdens of non-infectious disease the severe and wide-ranging impacts that that are equally important, and include exposure environmental degradation has on humans and to environmental pollutants (e.g., heavy metals animals – with multiple knock-on effects such as generated by extractive industries, air pollutants, food and water insecurity, climate regulation, the deliberate use of poisons), nutritional disorders dynamics of emerging and endemic diseases, associated with food scarcity, immunological and human wellbeing (Figure 1). Humans rely on dysfunction 11, and psychological disorders 12. animals for livelihoods and are susceptible to many of their diseases. Equally, wildlife species The combination of high biodiversity and are crucial to the normal function of ecosystems significant environmental change has led studies on which humans depend. Therefore, the health to predict hotspots for future zoonotic infectious of humans, animals and their environment are disease emergence in Africa 5,13. Human co-dependent and intrinsically linked. population growth and agricultural practices can lead to increased contact between wildlife, Increased reports of disease transmission livestock and people which can boost disease between wildlife, livestock and humans in transmission risk 3,14–16. Sustainable agricultural disturbed and degraded habitats emphasize the practices, particularly in African grasslands with impact of environmental change on human high biodiversity, can, to some extent, mitigate health, while showing that efforts are being made these risks 17,18. However, where these interfaces to improve disease surveillance and reporting are embedded within unsustainable land systems in these contexts 1–3. The concurrent management practices and linked to rapidly emergence of COVID-19, Ebola virus disease growing urban centres by the movement of outbreaks in DRC, Lassa fever in Nigeria and Rift people and animals (e.g., via livestock and Valley fever in Kenya has raised awareness of the wildlife value chains), they can facilitate the potential links between environmental change spread of emerging and endemic pathogens 19. and human health 4. Most emerging human This could have severe consequences for public infectious diseases (~60%) are zoonotic, health, societies, and economies on the meaning they spread from animals to humans. continent 20–22 (Figure 1). The majority of these (~71.8%) have a proximal origin in peri-domestic, farmed, or free-ranging Environmental stressors (e.g., exposure to toxins, wild animals 5,6. Conversely, some species of food shortages and human disturbance) are wildlife are also susceptible to human diseases increasingly being recognized as causes of poor (zooanthroponoses) – for example due in part to immunological health and reproductive their taxonomic closeness to humans, great apes performance in mammals and birds, threatening are acutely susceptible to diseases such as conservation efforts and potentially making measles and influenza 7. Land-use change (e.g., species such as bats more susceptible to deforestation, agricultural land conversion and zoonoses that can also affect humans 23,24 (see intensification, and urbanization) has the Box 1). In sub-Saharan Africa, the deliberate use potential to increase the risk of zoonotic disease of poisons to eliminate predators that kill emergence by reassembling biodiversity and livestock and to harvest animals for food, is 8 The Natural Environment and Health in Africa devastating entire scavenger communities and development efforts 27,28. However, a lack of posing a serious environmental hazard to evidence has made it difficult to communicate humans and livestock 25. Meanwhile, the loss of the importance and impact of the natural scavengers leads to an increase in feral dog environment on health to policymakers. As such, populations, potentially amplifying dog-borne health policy in Africa does not adequately zoonotic diseases such as rabies 26. consider or ‘price in’ the importance of Understanding these complex and often non- ecosystems in promoting health, and the linear connections between the natural negative effects that their disruption can have on environment, human and wildlife health is critical human health. to safeguard conservation efforts and to protect human and animal health in Africa. The objectives of this report are to 1) formulate a clear understanding of the connections between The combined effects of human and ecosystem environmental degradation, loss of biodiversity health have a considerable impact on human and health in Africa, using a systems approach, society. Mortality and morbidity attributed to 2) explore the impacts that the protection, and human and animal disease place a significant sustainable management and use of natural burden on rural and urban economies in Africa - resources and biodiversity have on human, through direct effects on human wellbeing and animal and ecosystem health, and 3) identify the the costs associated with seeking treatment, most pressing challenges and make caring for family members or loss of income or recommendations for how a One Health labour provided by patients, loss of animal framework could be used to address production, and lost wildlife tourism revenue - environmental and public health crises in Africa. which can restrict equitable, sustainable Figure 1. A conceptual model to show a system approach to understanding One Health in Africa, whereby one health outcomes are influenced by complex interactions between environmental and socioeconomic systems. Graphical images adapted from different sources: Urban population data from databank.worldbank.org/; biodiversity change data from Living Planet Report37; human population data from UN DESA Population Division38; climate change image credit Tjaden et al.39. The Natural Environment and Health in Africa Intended Audience For decision-makers and planners interested in the connections between the natural environment and health, it provides a high-level The reports intended audience are researchers, overview of how efforts to conserve species and decision-makers working in the environment and their habitats, and reverse environmental public health sectors, educators, and interested degradation, can impact human and animal individuals, including those who may not be health, and the practical barriers – in terms of familiar with the interdependence between the evidence, measurements, multi-sectoral natural environment and health. For academic collaboration, and training – that currently stand readers, it is not intended to be a definitive in the way of achieving desired health outcomes review of the scientific literature on this topic for humans and animals through the sustainable (which falls well outside the scope of this management of ecosystems. exercise) but highlights cross-disciplinary links between sectors, critical knowledge gaps, and For educators it provides a resource with which makes a series of recommendations that should to prepare teaching materials on One Health in help define research priorities moving forward. Africa, and for interested individuals to learn more about the potential connections between their health and the natural environment. Smithsonian “Outbreak” exhibition panels on display in pastoral communities in Kenya The Natural Environment and Health in Africa What is One Health, and why is it relevant in Africa? One Health has emerged as a framework for identifying, assessing, and strengthening the links between the health of humans and animals, and the natural and anthropological systems from which health outcomes arise 29. This approach was initially embraced by the public health community as a tool emphasizing multidisciplinary collaborations to prevent and manage infectious diseases (primarily zoonoses) at the interface between humans, animals and their shared environment, and has now been adopted by local, regional and global policymakers (including the FAO-OIE-WHO- UNEP Tripartite Alliance) as a framework for adapting to health threats such as emerging and re-emerging zoonosis and antimicrobial resistance (AMR) that have the potential to cause pandemics. Although the framework has become synonymous with zoonoses, its conception is broader than infectious disease – the One Health Commission defines One Health as “a collaborative, multisectoral, and trans-disciplinary approach - working at local, regional, national, and global levels - to achieve optimal health and wellbeing outcomes recognizing the interconnections between people, animals, plants 34 and their shared environment”30. follow others in using the term One Health to represent health in its broadest sense - from More recently, “Ecohealth” and “Planetary individuals to populations, and from infectious Health” have emerged as closely related and non-infectious disease to behavioural and approaches that focus on broader health spiritual wellbeing - as measured through its outcomes in the context of social and ecological impacts on human society and the natural world. change, and global sustainable development. Operating within this framework, academic and Scale is a key factor differentiating these Protiendcigenousand tsoiocianl s konof wledge from across the natural approachesP – rthoe mOnoe Htienalgth framework is ciences can be brought together to commonly used to emphasize health at the Critisrc ynathl esize effective solutions that address the interface beStwueesnt paeoinplea, banliym als and the oot cause of health issues, at local and regional environmenMt, EaconHaeaglthe cdon siders landscapes a Bs iodsicvalesr. sIni thyis way, the One Health framework socio-ecological constructs from which health Areacsan be used to improve human health and outcomes eLmaergned, asndc Palapnetasry Health livelihoods in a way that also addresses the considers health as an outcome of the planet’s social and environmental factors that ultimately natural systems, with a particular emphasis on drive health outcomes and epidemiological “informing decision-making in the land-use processes on an interconnected planet. planning, ocean-use planning, environmental conservation and public health realms” 31–33. Africa s a biologically and culturally diverse Given similarities and convergence between continent, home to some of the world's most these terms, and the widespread familiarity of important ecosystems, vibrant cultures, and One Health with the public and pCollicimymakteers, Cweh anegndea ngered and iconic species of plants and Adaptation and Mitigation 11 A S no Ec nie gt ay ged ng nt een i pm e Gr ovel De The Natural Environment and Health in Africa animals. The continent maintains a quarter of only consider human and animal health there is global biodiversity, which provides vital terrestrial the need to integrate the environmental and aquatic ecosystem services to the planet, component. Since the environmental drivers of while bringing economic prosperity to more than biodiversity loss and human health are so closely a billion people and supporting the world’s linked, public and private stakeholders who are largest intact assemblages of large mammals 38. working to reverse biodiversity loss and promote Human populations across Africa are growing at sustainable development in Africa’s rangeland, an unprecedented rate, and the continent is forest, freshwater and ocean ecosystems, are projected to account for 40% of the world’s uniquely positioned to lead these efforts. Many population (4.4 billion people) by 2100 36,39. of these organization also have access to direct Rates of deforestation in Africa are currently engagement opportunities with policymakers on twice the global average, and efforts to increase topics fundamental to One Health, such as agricultural output have resulted in land area biodiversity and habitat preservation, food expansion and dependence on fragile systems, climate and education. ecosystems, often rather than improvements to the yield of existing systems 40. Global drivers of environmental change, such as climate, are also predicted to have a considerable impact on Africa 41. Resulting land use change, biodiversity loss, and degradation of natural systems will have impacts on human health and livelihoods. The fate of Africa's ecosystems are deeply intertwined with the continent’s economy - raising incomes in sub-Saharan Africa to the current global average will “require an increase in the region's annual output from 3.5 trillion international dollars to about 68 trillion international dollars” 42. For this to be achieved without enormous ecological damage and risks to human and animal health, sustainable economic growth must be embedded within nature. Because environmental issues and health crises go hand-in-hand, governments will benefit from the support of national and international stakeholders to effectively manage and conserve their natural resources and ecosystems, while also securing the health of their citizens. The One Health framework is particularly relevant to Africa since the natural environment supports most of the continent’s growing economies, yet environmental degradation poses an increasingly severe threat to the health and wellbeing of humans and animals 43. While One Health approaches are increasingly being adopted at a local scale across the African continent, these initiatives are often poorly connected and therefore inadequate to address ecological and social dynamics taking place at a national and regional scale. As such the need for small-scale initiatives to be connected and integrated into intersectoral long-term One Health initiatives is increasingly recognized 44. WherCe tlhiemsea efftoert sC hange Adaptation and Mitigation 12 The Natural Environment and Health in Africa Mapping the impacts of environmental degradation on health in Africa Understanding how health emerges from the direction. For example, for a study titled complex interactions between human activities “Population Dynamics of Owned, Free-Roaming and the natural world requires integration of Dogs: Implications for Rabies Control” the knowledge, evidence, and research programs components and relationships were: across ecological, social, and health domains. System dynamics provides a methodology for domestic dogs -> zoonoses (positive); zoonoses representing these interactions as a system, -> human health (negative) allowing mapping and identification of the relationships between different sectors47. By Relationships between components were only using a system dynamics approach to represent included where there was evidence to suggest a the connections between the natural causal interaction. This information was also environment, human activities and health in extracted from review papers. Africa as a system, we depict how health emerges from Africa’s landscapes (using causal Despite implementing a comprehensive maps), identify relationships between different approach that provides an accurate sectors, and assess the evidence that underpins representation of research being conducted on our understanding of health on the continent. One Health across Africa, not all connections between the natural environment and health in A systematic literature review of peer-reviewed Africa will have been captured in this review. publications featuring components of One Research and reporting biases mean that the Health, EcoHealth or Planetary Health from review process will have missed a subset of ecological, social and health domain across peer-reviewed publications, containing Africa was performed (see Appendix for full components that may not be represented in our methods). A total of 1,446 article abstracts were work. To address these limitations, experts screened according to a set of criteria aimed at working on topics related to One Health in Africa filtering irrelevant articles and duplicates, and were recruited from diverse domains including those published between 2015 and 2021 were conservation, ecology, food systems and selected for in-depth review (n=616). These nutrition, epidemiology, economics, social publications were used to identify and extract sciences and policy. Experts reviewed and different components of the natural environment validated the system models to identify missing and society relevant to health, and the feedback components and relationships, thereby providing and interactions between them. a more complete understanding of One Health in Africa. Causal loop diagrams (Figures 2, 3, 4 and 5) were constructed, with arrows linking the It should be stressed that while relationships variables with the polarity of the interactions were only included between components where represented by a plus or minus sign at the there was some evidence to suggest an arrowhead. Positive polarity represents association, the causal loop diagrams do not interactions where a change in an independent differentiate between strength of evidence variable causes a change in the dependent underlying these associations, many of which are variable in the same direction, and negative speculative and not backed up concrete data. polarity indicates a change in the opposite 13 The Natural Environment and Health in Africa One Health in Africa Dust1 + Positive relationship Dust2 - Negative relationship Dust3 * Positive and negative relationship R Reinforcing loop +Dust B RBalancing loop + + Climate + Carbon +change emissions + - Conflic+t + + Agriculture Sustainable + agriculture - + Soil quality - + + - Water security B Crop Air + production pollution+ + - - +Food Livestock - security - production + Fisheries+ + - Urbanization+ + Livestock trade + + WaterSocial -quality + Nutrition + equality - Veterinary Waste + healthcare disposal+ - Foodsafety + - - Extractive +industries + + + Corruption - - - + - Land use + Poverty Deforestation + + + change Pandemics + + - + + R + HabitatPollution + degradation + + + + Bushmeat + +- consumption + Antimicrobial - + + resistance +Zoonoses + ++ + * - + + Tourism + Cultural Domestic - * + practices + animals - - + -- Wild Biodiversity - - animals + - + - Freshwater Human - - ecosystems health Marine - + ecosystems Human-wildlife + Desert - -i+nteractions ecosystems - + + + Grassland Ecosystem - Algal ecosystems health blooms- Forest + Human ecosystemspopulation - expansion + Invasivespecies + Figure 2. A systems map for health and the environment in Africa. Interactions across sectors are incorporated to gain a better understanding of this complex system. Arrows indicate a connection between variables, with a (+) signifying a generally positive effect, (-) a generally negative effect and (*) a positive and negative effect. Reinforcing interactions whereby change in one direction is intensified by more change in the same direction are represented with a red R in a circular arrow. Balancing interactions in which change in one direction is countered with change in the opposite direction are shown with a black B in a circular arrow. Colours signify variables that are influenced by ecosystem services (green), land use change (yellow- brown), agriculture (orange), climate change (blue), human health (red), plus veterinary healthcare (purple). Health in Africa as a consider the relationship between biodiversity, habitat degradation and health, other indicators system of ecosystem health such as function (e.g., connectivity and pollution) and resilience (e.g., impact of invasive species, climate change Figure 2 depicts the relationships, interactions adaption) are lacking. For example, pollution due and trade-offs between health, the natural to agrochemicals (pesticides and fertilizers) and environment and human activities in Africa, as heavy metals emerge as important components represented in the systematic review and expert of the system, but studies in Africa opinion. Research that was reviewed in Africa predominantly focus on their accumulation in has a predominant focus on zoonoses, especially aquatic wildlife and the threat this may pose to involving rabies in domestic dogs, diseases of human health, rather than measuring their direct veterinary importance (such as brucellosis and impact on human and animal health, or tuberculosis) and select emerging pathogens ecosystem function. Similarly, although climate such as Rift Valley Fever and human exposure change, land use change and agriculture are risk for Ebola virus. While a few studies do 14 The Natural Environment and Health in Africa important drivers influencing the health in Human and animal health as emergent numerous ways, little information exists on the properties of climate change, land use effect of urbanization on the system, the impacts change and agriculture, with a focus of climate change on ecosystem health, or the transmission of disease across species synergistic effects of different drivers on human health. When considering disease emergence from a systems perspective, it is useful to think “bottom Due to the complexity of the system represented up”, where health outcomes emerge from three in Figure 2, three submaps were developed to core underlying drivers – cultural practices, represent in more detail the following sections of human population growth, and climate change. the main map that were deemed to be of The impacts of these anthropogenic drivers on particular relevance to health outcomes that terrestrial and aquatic ecosystems occur at local emerge from the natural environment. to regional scales and are collectively referred to as land-use change. Terrestrial forms of land-use change are represented in Figure 3 by deforestation, pastoralism, intensive agriculture Figure 3. The bottom-up impacts of human (e.g., small holder agriculture and arable farming) population growth, changing cultural practices, and urbanization, while fresh water and marine and land-use and climate change on human and fisheries represent aquatic land-use change. The animal health, with a focus on spillover of zoonotic downstream effects that different forms of land- pathogens between animals and humans. use change have on pathogen spillover can be Protection of Promoting Critical Sustainably Biodiversity Managed Areas Landscapes Climate Change Adaptation and Mitigation A S no Ec nie gt ay ged ng i en t Gre en lop m De ve The Natural Environment and Health in Africa grouped into three thematic ‘plumes’ – The wildlife trade connects the biodiversity and biodiversity and habitat, food supply chains and habitat plume to animal-sourced food supply demographics, pollution, antimicrobial resistance chains, and poverty and social equity (such as and healthcare. gender, see Box 5). Animal-sourced food supply chains are a major route for zoonotic pathogen Under the biodiversity and habitat plume, exposure in people and can promote biodiversity loss and fragmentation antimicrobial resistance through transmission of simultaneously create novel opportunities for food borne AMR bacteria or AMR residues in contact between wildlife, humans and livestock animal source foods exposing the human (or just wildlife and livestock in aquatic systems) bacteria to low doses of AMs, but also have by redistributing wildlife assemblages, while positive nutritional impacts on human health. acting as ecological stressors that shape the Finally, in the third plume, agricultural outputs in susceptibility of wildlife to pathogens and drive the form of pollution and pesticides exacerbate patterns of pathogen shedding (see Box 1). This biodiversity loss (and therefore health impacts of ultimately has the potential to lead to spillover of the biodiversity plume) and have adverse health wildlife-borne pathogens to humans or livestock effects on humans and animals that may (see Box 2), or pathogen transmission from increase their susceptibility to infectious disease domestic species or humans to wildlife. (e.g., through comorbidities and immunotoxicity). Heavy metals can induce antimicrobial resistance, making pathogens more virulent, and Figure 4. The bottom-up impacts of human reducing the effectiveness of human and animal population growth, changing cultural practices, healthcare46. and land-use and climate change on human and animal health, with a focus on food systems. Promoting Sustainably Managed Landscapes Climate Change Adaptation and Mitigation A S no Ec nie gt ay ged ng ni me nt Gre e lop De ve The Natural Environment and Health in Africa Perhaps most importantly, Figure 3 highlights (Figure 4). As for the infectious disease system cross-cutting components – such as biodiversity represented in Figure 3, health outcomes arise loss and habitat fragmentation, invasive species, from the underlying drivers of cultural practices, poverty, pollution, conflict and pandemics – human population growth, and climate change. which play a vast role in regulating the processes Unsustainable agricultural practices, such as occurring in different thematic plumes that livestock and crop cultivation, negatively impact ultimately lead to cross-species pathogen the natural environment via habitat spillover. fragmentation, biodiversity loss and chemical pollution (e.g., pesticide use and poor waste Human and ecosystem health as management, which can also cause direct emergent properties of food systems contamination of animal and plat-sourced foods). This has cascading impacts on wildlife and Mapping the interactions between food systems human health, through changes in human-wildlife and health in Africa reveals wide-ranging and wildlife-livestock interactions, rates of interactions within the different components zoonotic pathogen spillover, agricultural yields, food supply chains, and livelihoods. Important dynamics emerge between food security, infectious disease (e.g., zoonoses, food-borne Figure 5. The bottom-up impacts of human disease and antimicrobial resistance), population growth, changing cultural practices, socioeconomic factors and nutrition. This reflects and land-use and climate change on human and the importance of poverty traps, a self- animal health, with a focus on ecosystem reinforcing mechanism enabling poverty and services and human health. diseases to persist (represented in Figure 4 as a Promoting Sustainably Managed Landscapes Climate Change Adaptation and Mitigation A S no Ec nie gt ay ged ng ent eni Gre m elo p evD The Natural Environment and Health in Africa positive relationship between poverty and system and are both affected by the function of zoonotic spillover and vice versa) 47. and play a role in the success of all four ecosystem services. Deforestation negatively Agrochemical use and waste flows from impacts regulating, provisioning, and supporting agriculture and urbanization also lead to services and reduces biodiversity which supports contamination of aquatic environments, all ecosystem services. Extractive industries, negatively impacting fisheries and drinking water, urbanization, agriculture, and fisheries promote and therefore agricultural yield, nutrition, and habitat destruction and biodiversity loss, further water security. There is some evidence depleting – sometimes irrevocably - all services, connecting the impact of sustainable agricultural and negatively impacting human health. practices in Africa to ecosystem health (for example the contribution of sustainable agriculture to climate resilience 48), and their How are efforts to potential impact on the system through understand the links increasing ecological resilience should be highlighted. between the natural Human health as an emergent property of environment and health ecosystem health and the impacts of distributed across the anthropogenic change on these ecosystem services, with a focus on non- African continent? infectious disease Geographic patterns in the distribution of Ecosystem services are the benefits that people research effort across Africa are evident from the realize from healthy, biodiverse environments 49. results of the systematic review, and likely reflect These services are categorized as provisioning, differing levels of investment in research regulating, cultural, and supporting services, with activities (with roots in historical inequality and the latter required to bolster the first three. societal stability), public health priorities and Provisioning services account for the production adoption of the One Health approach (Figure 6). and furnishment of raw resources such as food, For example, food systems in particular seem to water, materials (e.g., timber, minerals), and play an important role in determining where medicinal products. Regulation of climate, air research efforts are focused. For instance, there quality, water purification, flood regulation, is a geographic focus on One Health studies of pollination and other biological control aquatic systems and the wildlife trade in West mechanisms comprise regulatory services, while Africa, where fish and wildlife are predominant aesthetic, spiritual, educational, tourism, sources of protein, and outbreaks of Ebola and recreational, physical and mental health benefits Lassa fever have raised awareness of the comprise cultural services. Finally, ‘supporting connections between human health and the services,’ underpin and strengthen provisioning, natural environment. Similarly, most studies on regulation and cultural services through zoonoses at the wildlife-livestock-human maintenancPe orfo hambitoatt aindg ge netic diversity, interface are conducted in areas of Southern and nutrient cycSlinug, ssotial fionrmaabtiolny, primary Eastern Africa where extensive agricultural production50. Biodiversity under pins all robust systems dominate. ecosystem Mservaicnesa agnde ids v ital to their functioning.L Eaconsydstsem services impact human Particularly striking are the geographic gaps health and wellbeing inc daivpereses and numerous where little research effort is being made to apply ways to include their impact on nutrition and a One Health approach. Large parts of south- livelihoods associated with the provision of food western Africa, central Africa and the Sahel – all and water, regulation of infectious and non- areas that contain biodiversity hotspots, human infectious diseases, climate and weather, and populations vulnerable to environmental change, support of spiritual, physical, and mental health. and landscapes known to harbour emerging pathogens 51 – are underrepresented across Mapping the connections betweCenl eimcosaystteem C hantghematic areas. Although the systematic review services and anthropogenic drivers in Africa wilel h ave missed research activities taking place reveals their far-reaching influenAced ona hpumtaant ion aninod e ach country (particularly unpublished work), health through factors such as access to food ur methods were not geographically biased, and and water, social equality, use oMf inditigiegnaoutsi on we therefore feel confident that these maps give knowledge and exposure to the ozone (Figure 5). a broadly accurate representation of peer- Climate change and invasive species are reviewed research being generated across the revealed as important components within the continent. A S no Ec nie gt ay ged ng ni me nt ree opG eve l D The Natural Environment and Health in Africa Promoting Sustainably Managed Landscapes FIGURE 6: GEO GRA PCHli mICa tBe IC AhSan IgNe Adaptation and ON E HEALTH RESEARCH BEING CMOiNtigDaU tioCn TED IN AFRICA Maps showing the distribution of research conducted within different thematic areas of One Health across the African continent. Patterns that emerge indicate differing levels of investment in research activities (with roots in historical inequality and societal stability) and public health priorities. A S no Ec nie gt ay ged ing nt en pm e Gre oeve l D The Natural Environment and Health in Africa The impacts of environmental protection and biodiversity conservation efforts on health In this section, efforts to reverse environmental degradation and biodiversity loss are linked to health outcomes by identifying mechanisms by which existing work being conducted to protect and restore terrestrial and aquatic ecosystems can have direct, or indirect, impact on human and ecosystem health. These efforts are split into six ‘impact areas’ – broad topics on which those working in the environment sector might aim to have impact. Acknowledging the importance of data-driven evidence for guiding and determining the value and impact of conservation activities on health, each mechanism is also assigned a level of evidence. While subjective, this rating (weak, moderate or strong) of evidence for mechanisms connecting the natural environment to health in Africa is based on the systematic review and opinions of the experts who were consulted through this process. Because epidemiological and ecological processes are scale dependent, the geographic scale (site, landscape, regional or global) at which health outcomes in humans and animals can be expected to emerge is also indicated. Nature Positive Finance Protection of Promoting Critical Sustainably Biodiversity Managed Areas Landscapes Climate Change Adaptation and Mitigation 20 A S no Ec nie gt ay ged ing en t een mGr elo p evD Protection of critical biodiversity areas Reducing biodiversity loss and habitat wide ranging impacts on human and animal fragmentation, and increasing habitat health related to air quality, food and water connectivity, represent core activities security, invasive species, extreme weather conducted by many conservation organizations events, conflict mitigation and access to aimed at protecting critical habitats in key medicinal plants. conservation areas and maintaining critical ecosystem services. Breakdowns in ecological Protection of lands and waters therefore integrity, characterized by biodiversity loss and represent ecological countermeasures, habitat fragmentation, are considered drivers for functioning as ecosystem services that could be the transmission of pathogens from wildlife to our best defence against zoonotic disease humans (often via their livestock). Spillover of emergence, while improving health outcomes in zoonotic disease from wildlife can occur via many other, potentially more impactful, ways human practices that promote direct contact (readers are encouraged to refer to Reaser et al. with wildlife products (e.g., wild meat harvesting 57 and Reaser et al 58 for a thorough discussion and trade), or through distributional changes in of these topics). Considerably more evidence on the ecology of wildlife hosts in response to mechanisms linking ecosystem degradation to restructuring of ecological systems resulting from zoonotic disease emergence (beyond the wildlife habitat loss and human development, that bring trade) and the collapse of ecosystem services is them into closer contact with humans and their required to design and test interventions and livestock and influence the abundance of measure the health impacts of landscape pathogens they carry (see Box 1). The impact of conservation activities. However, the grave risks biodiversity loss on pathogen dynamics through posed to human and animal health necessitate a changes in host species composition is context strong response. Beyond broader habitat specific – in general, pathogens that interact with remediation and restoration activities (see Box 2), more species in an ecosystem are more likely to this could include measures that minimize be affected by biodiversity loss 52. For example, contact and therefore transmission of diseases by supporting a greater abundance of non- between wildlife, humans and their livestock competent hosts, biodiversity can “dilute” the (e.g., land use zoning, and fencing (although this abundance of pathogens such as hantavirus and can be counterproductive – see Box 3)). In Borrelia spp. (known as the dilution effect), while addition, enhanced monitoring and response increasing the abundance of competent hosts for systems for infectious disease, human-wildlife other pathogens (which increase in prevalence contact, and other downstream impacts of as a result). By modifying the reproductive habitat degradation on animal and human health potential of vectors, land use change can also are required. have positive and negative impacts on non- zoonotic vector-borne pathogens, such as malaria 53, schistosomiasis 54,55, and African trypanosomiasis 56. In addition to influencing infectious disease dynamics, competition for resources (such as food) due to biodiversity loss and habitat fragmentation often results in human-wildlife conflict, elevating mortality rates in human and animal populations. Perhaps most important, loss of ecosystem integrity leads to the collapse of the regulating, supporting and provisioning services that they offer, with the potential for 21 The Natural Environment and Health in Africa The potential impacts of strategies to protect critical biodiversity areas on health Strategy Health Implications Evidence Refs Geographic Scale Reduces amplification and spillover risk from reservoir hosts of zoonotic Weak, site 59–61,62 Site, Landscape, Reduce habitat disease specific Regional, Global fragmentation and biodiversity loss Reduces dispersal of pathogens, vectors, and hosts into new geographic areas Weak 60,62,63 Landscape, Regional, Global Reduces ecological stress, thereby improving wildlife population fitness and Weak 3,64 Landscape, Regional, reducing shedding of zoonotic pathogens Global Reduces vector populations, reducing risk posed by vector-borne disease Moderate 65,66 Site, Landscape Provides resources for improved human nutrition and livelihoods, and medicinal Moderate 67 Site, Landscape resources Regulates the impacts of climate change, air quality, water quality and natural Moderate 67 Landscape, Regional disasters on human health Supports ecotourism which benefits livelihoods and therefore human health Moderate 67 Site, Landscape Provides pollinator habitat, supporting pollination as a core ecosystem service Weak 67 Landscape Supports cultural ecosystem services, improving mental health Moderate 67 Site, Landscape Improves immune function, reducing chronic allergy and inflammatory diseases Weak 68 Site Supports indigenous knowledge systems, improving livelihoods, mental health Moderate 67 Site, Landscape and plant-derived medicines knowledge Protects against invasive alien species incursion, preventing further biodiversity Moderate 67,69,70 Site, Landscape, loss and habitat fragmentation Regional Reduces risk of conflict resulting from loss of natural resources, which impacts Weak 71,72 Landscape, Regional infectious disease, food and water security and access to healthcare Genetically diverse wildlife populations are less susceptible to diseases Strong Landscape, Regional Improved connectivity 73 between habitats Increases circulation of zoonotic pathogens between wildlife and livestock, Moderate 74,75 Site when grazed in the same landscape Results in changes in human-wildlife conflict (context specific) Strong 76 77 Site Enhances biodiversity which underpins all ecosystem services Moderate 67 78 Landscape Supports food security, human nutrition, and livelihoods for indigenous peoples Weak 67 Site, Landscape Enhance monitoring of Reduces the likelihood of zoonotic disease outbreaks propagating and spilling Strong 34,62,79–81 Site, Landscape, animal health, and over into people Regional, Global improve response Improves global health security and reduces the likelihood of pandemics Strong 34,79,82 Global capacity Supports conservation efforts, reduces agricultural losses, therefore improves Strong 34,80,83 Landscape livelihoods Enhance monitoring Reduces demand for wildlife products, reducing wildlife mortality and the Moderate 84 Site, Landscape, and policing of likelihood of zoonotic pathogen spillover Regional, Global extractive industries Reduces poisoning from heavy metals Weak 85 Landscape Reduces impact of heavy metals on AMR in bacteria Weak 86 Site Enhance monitoring of Integrated monitoring of biodiversity and ecosystem services using indigenous Weak 67 Landscape biodiversity and peoples and local community knowledge is needed to assess the impacts of protected areas on ecosystem services ecosystem services Use of advanced analytical methods is needed to assess the impacts of Moderate 87 Landscape protected areas on ecosystem services 22 The Natural Environment and Health in Africa Box 1: Land use induced spillover and ecological stress Biodiversity loss and habitat fragmentation are considered fundamental drivers for the transmission of pathogens to people and their livestock (emerging zoonoses and agriculturally important diseases), and from people and livestock to wildlife (anthroponoses). This can occur via several mechanisms, which have been suggested and tested through theoretical modelling 60,88 and demonstrated empirically (albeit in a very limited capacity) for different host-pathogen systems. Mechanisms by which ecological degradation is known to promote cross-species pathogen transmission include: i) human incursions into wildlife habitats, through which people can be directly exposed to wildlife-borne pathogens through harvesting and trade of wildlife products 89,90, and through which wildlife can be exposed to human pathogens (e.g., great apes and tourism 91,92); ii) changes in the distributional ecology of wildlife hosts in response to changes in the availability of natural resources (such as food), which brings wildlife into direct contact with livestock and humans, facilitating transmission of pathogens 93,94; and iii) changes in the abundance and shedding of wildlife and livestock-borne pathogens through changes in host abundance, diversity and susceptibility to infection (for example, through ecological stressors) 95–97. While strong evidence exists for these mechanisms as they apply to specific disease systems (e.g., Hendra virus in Australia), they are poorly studied as widespread phenomena. “Land use-induced spillover” provides a framework for understanding the processes by which land-use change drives the emergence of novel pathogens from free-ranging wildlife 62. This process can be broken down into three components: infect, shed, and spillover. Driving these components is environmental stress – human activities, such as deforestation, agricultural development and urbanization, that change the availability of resources on which wildlife rely. Shifting resource availability can favour peri-domestic species (such as rodents), which may be more competent hosts for zoonotic pathogens 3,98. For bats, which host a disproportionately large number of zoonotic viruses, land conversion can modify their foraging patterns making them travel further and congregate in higher numbers. When wildlife congregate at higher densities, zoonotic pathogens have access to more susceptible hosts, and can therefore be amplified within infected populations 99,100. Meanwhile, stress caused by loss of resources such as food and human disturbance can negatively impact their immune system, which has the potential to result in more viral shedding 97,101,102. Spillover occurs when a susceptible human (or their livestock) receives a sufficient dose of a viral pathogen from wildlife to become infected 103. Anthropogenic activities can provide opportunities for this to occur by promoting contact between wildlife and humans. For example, agricultural practices and urbanization in Australia and South East Asia that provide food sources for bats in the form of fruit trees, have been shown to promote contact between bats, people and their livestock, resulting in spillover of Hendra and Nipah viruses 104,105. In Africa, deforestation has been linked to changes in fruit bat distribution and Ebola virus emergence, but the mechanisms by which this occurred have not been described 106. The Natural Environment and Health in Africa Box 2: Translocations, conservation and health Habitat loss and fragmentation – particularly through agricultural and urban development which create artificial barriers to movement – poses an extinction risk for many populations of wild animals, which rely on dispersal areas for food and to effectively reproduce. In these scenarios, human-mediated movement of imperilled and keystone species (translocation 107) is required to secure wildlife health through genetic exchange between the fragmented populations, and improve the resilience of wildlife to threats such as disease epidemics, invasive species, habitat loss and climate change 108. In Africa, translocations are also being used to resolve human- wildlife conflict, as a humane alternative to otherwise lethal solutions 109. In addition to supporting wildlife health, veterinary management of key-stone species broadly impacts ecosystem function, human health, and stability of livelihoods. By reintroducing species that occupy important trophic levels as a component of restoration ecology (or ‘rewilding’), translocations can restore ecosystem balance that holistically provides critical services to support wildlife and human populations. These efforts can also promote alternative livelihoods for local human communities through ecotourism, decreasing the likelihood of poaching and deforestation, and supporting education. More complex interventions that involve translocating wildlife to outside their indigenous ranges, are now being performed to improve the status of focal endangered species, or improve natural ecosystem functions using non-native taxon substitutions 107,110,111. An example of a successful restoration effort comes from Gorongosa National Park in Mozambique, where extirpation of megafauna through over a decade of civil war brought large herbivores and carnivores to the brink of extinction 112. However, through strategic translocations and effective community conservation measures conducted since 2008, wildlife populations have started to recover in parallel with government-supported economic and educational development in the surrounding communities 113. In addition, the recovery of large mammal populations has been improved ecosystem functions, for example by containing encroachment of the invasive shrub Mimosa pigra which negatively impacts biodiversity and water resources 114. This demonstrates the impact that restoring key-stone species can have on ecosystem function, and the health and welfare of surrounding communities. However, translocations also carry risks – to the health of the individuals being translocated, to native species, and to ecosystems within which the focal species are being moved (e.g., translocation of pathogens into naïve resident wildlife populations). A comprehensive risk assessment, conducted by a scientific and technical team, should always be performed as part of any translocation 107,115. At a minimum this should consist of a pre- translocation health screening and an assessment of the ecological suitability of release sites, and post- translocation monitoring for space use and settlement in the recipient area, survival rates and demography, and reproductive output in order to establish viable breeding populations 109,115,116. Unfortunately, species-specific knowledge gaps and a lack of funding mean that efforts to mitigate negative outcomes and monitor the success of translocations are often not conducted. 24 The Natural Environment and Health in Africa Box 3: Control measures at the wildlife-livestock-human interface Protected areas in southern and eastern Africa play a crucial role in sustaining biodiversity and supporting humans and their livestock 117. In most cases, however, these areas are insufficient at providing the spatial needs of many large mammals. Across Kenya, for example, more than 65% of wildlife occur outside formal protected areas, demonstrating the tentative co-existence between wildlife and local people 118. Maintaining connectivity across habitats – within and outside protected areas - is therefore crucial to the conservation of large herbivores and Eland crossing a fence in Laikipia, Central Kenya carnivores, and normal function of the ecosystems in which they exist. The use of fences to separate wildlife from people and their livestock as a means of zoonotic and non-zoonotic disease control, and to mitigate human-wildlife conflict, is widely practiced in southern and eastern Africa. However, veterinary cordon fences, used extensively across South Africa, Botswana, Namibia and Zimbabwe to control economically important diseases such as foot and mouth disease (FMD) and bovine tuberculosis, interrupt the seasonal movement of wildlife and have catastrophic effects on populations of wildebeest, zebra, elephants and other migratory species that are unable to access grazing and water resources 119. These fences are also responsible for causing traumatic injuries to wildlife. In addition to direct negative impacts on wildlife, veterinary cordon fences have been shown in some cases to increase human-wildlife conflict around crops and water resources. Similarly, fenced livestock who are no longer tended by herders are at increased risk of theft, or may break through fences, heightening their risk of predation or injury, resulting in grave economic losses 119. While fencing may limit exposure of livestock to economically important diseases that are maintained in wildlife – thereby potentially delivering substantial cost savings through addressing production losses, human nutrition and public health – the negative impacts of veterinary fences on wildlife conservation and the ecosystem services that intact landscapes provide are infrequently considered 120–122. Veterinary fencing has not been as extensively used in East Africa, but as a result of human population pressures these landscapes are now experiencing rapid change. Roads, fences, and other alternative land-uses have expanded across the region, leading to loss and fragmentation of available habitat and resulting in widespread declines in wildlife, animal movement, and people’s livelihoods 123. In an era of global environmental change, maintaining connectivity across landscapes is crucial to ensuring the resilience of wildlife and human populations to erratic weather (such as drought and flooding) that can affect availability of pasture. Fortunately, opportunities now exist to address this. Initially spearheaded by the Animal and Human Health for the Environment and Development (AHEAD) program, new approaches to managing diseases of veterinary importance to promote holistic land management (such as vaccination) can be combined with research to determine contextual differences in the epidemiology of these diseases in different countries 78,124–127. Where fencing is indicated for conservation purposes or to protect human livelihoods, clearly established goals that are regularly revisited should differentiate the requirements of different species within ecosystems 128. Wildlife corridors or underpasses can be used to maintain connectivity between fenced and unfenced landscapes. Perhaps most importantly, there is a need for economists and epidemiologists working on veterinary public health to partner with those studying the economic value of wildlife and ecosystem services, to develop robust, data-driven policy. Land managers must also work with local communities to promote and protect their land and user rights while providing incentives that reduce land subdivision and increase economic returns from wildlife conservation. Promoting sustainably managed landscapes Grasslands, forests, freshwater and marine integrity, reducing carbon storage capacity of ecosystems across much of Africa are grasslands, which contain up to 30% of global critically important ecological systems, carbon and sequester even more 130,131. which act as a refuge for biodiversity while Agricultural run-off and resulting eutrophication supporting people and the animals they rely on. leads to the creation of ‘dead zones’ in aquatic Their degradation and eventual collapse environments, impacting food and water security, simultaneously threaten conservation, food and burdens of non-infectious disease (see Box security, human health, economic stability, and 4). When practiced unsustainably, all forms of climate change mitigation efforts. Therefore, agriculture can increase greenhouse gas integrated, sustainable management of these emissions while reducing the ability of ecosystems must be a key component of ecosystems to perform carbon sequestration, conservation, economic, and public health with widespread and severe implications for strategies on the continent. For example, in health in the future. Kenya, wildlife roam across 70% of the nation’s grasslands, yet only 8% of those areas are Conflict between people and wildlife is protected. Therefore, shared rangelands – often detrimental to conservation efforts, human health under the stewardship of local communities – are and livelihoods, and the natural environment (see crucially important to conserving biodiversity and Box 5). In addition, illegal wildlife harvesting and the ecosystem services it provides 129. trade pose considerable risks to threatened species as well as human health via the potential Agriculture is a vital source of nutrition and for zoonotic pathogen spillover and ongoing livelihoods for people in Africa and is therefore of transmission across the world. Understanding enormous importance to human health and the socioecological drivers behind these issues wellbeing. However, when practiced is key to safeguarding human health and unsustainably, agriculture can have widespread protecting wildlife (see Box 6). At a landscape direct negative impacts on human and animal scale, holistic approaches are required to ensure health, as well as on the ecosystem services that biodiversity conservation, preservation of support health. For example, intensive farming ecosystem services, human wellbeing, and and aquaculture practices can lead to economic activities. Integrated landscape amplification of zoonotic disease and, through management, that promotes biodiversity injudicious use of antibiotics, can promote the conservation, sustainable livestock rearing, emergence of antimicrobial resistance in sustainable wildlife harvesting, and control of humans, animals and the environment. Poorly invasive species (Box 7) can create working managed extensive farming practices such as landscapes in which people live in harmony with overgrazing of grasslands has the potential to and create benefits from cohabitation with promote spillover of pathogens between wildlife wildlife. and humans or livestock, and cause human- wildlife conflict. In addition, overgrazing impacts climate change through degradation of soil Giraffes on Mbirikani group ranch in southern Kenya The Natural Environment and Health in Africa The potential impacts of sustainable landscape management strategies on health Strategy Health Implications Evidence Refs Geographic Scale Integrated landscape Ensures ecologically sustainable economic development and integrated Moderate 67 Landscape management resource management to safeguard ecosystem health approaches Provides resilient food systems that ensure food security, nutrition, and Weak 67,132 Landscape livelihoods during environmental perturbations Integrated livestock When properly managed enhances biodiversity, improving agricultural yields, Moderate, 133,134 Site, Landscape management and human nutrition and livelihoods context specific conservation Improve sustainability Improves food and water security, nutrition, and livelihood security by reducing Moderate 134,135 Landscape of agriculture, livestock overgrazing aquaculture, and Diversified systems increased the resilience of food systems Moderate 134,135 Landscape fisheries practices Reduces need for antimicrobial use in food-producing animals, reducing Strong 136 Landscape antimicrobial resistance in humans and animals Reduces exposure to agrochemicals which can cause non-infectious diseases Weak 136–139 Site, Landscape such as cancer Improves access to safe drinking water Weak 140 Site, Landscape Reduces standing water that can act as vector breeding sites, reducing vector- Weak 141 Landscape borne disease burdens Reduces human-wildlife conflict, leading to improved agricultural yields and Moderate 77 Site livelihoods Improves biodiversity and ecological resilience leading to improved food Weak 67 Landscape, Regional security Reduce human-wildlife Reduces wildlife mortality, directly improving conservation efforts Strong 77,142–144 Site conflict Improves agricultural yields, improving food security, nutrition, and livelihoods Moderate 77,143 Site Reduces poison use, improving water quality and security, food safety, Weak 142,143 Site biodiversity, and wildlife health Reduces negative impact of poisons on ecosystem services provided by Weak 142 Landscape scavengers, reducing zoonotic diseases. Supports cultural practices and ecotourism which improve mental health and Moderate 67,143 Site livelihoods Enhances biodiversity which underpins all ecosystem services Moderate 67 Landscape Enhanced monitoring Reduces wildlife mortality, improving conservation efforts and maintaining Strong 67 Landscape and control of illegal biological diversity wildlife trade Control of supply chains reduces exposure of consumers in populous areas to Weak 145,146 Regional, Global wildlife-borne pathogens, where outbreaks of novel pathogens can quickly amplify into epidemics or pandemics Reduces mortality of non-target species (e.g., scavengers) and threat posed by Weak 142,147 Site poisoning from consumption of wildlife products Reduces food supply chains and negatively impacts food security, poverty, and Moderate 148–150 Landscape, Regional livelihoods Enhances biodiversity which underpins all ecosystem services Weak 67 Landscape Sustainable harvesting Reduces risk of exposure to zoonotic pathogens by addressing risk practices Absent 67 Site, Landscape, of wildlife and species targeted. Regional, Global Improves resilience of food systems, improving nutrition and livelihoods Moderate 67,132 Landscape, Regional Enhances biodiversity which underpins all ecosystem services Weak 133,134 Landscape Enhance monitoring Reduces impact on vector-borne disease and ecosystem services Moderate 134,135 Site, Landscape and control of invasive Reduces interface between wildlife, livestock and humans, reducing zoonotic Weak 134,135 Site, Landscape, species pathogen spillover and human-wildlife conflict Regional, Global Enhances biodiversity which underpins all ecosystem services Moderate 136 Landscape, Regional Forecasting and mitigation of invasive species Moderate 136–139 Landscape, Regional The Natural Environment and Health in Africa Box 4: The impact of organic chemicals on fisheries African fisheries provide a source of livelihood for 35 million active fishers and their families, many of whom are engaged in subsistence and small-scale fishing 155. Until recently, studies on aquatic ecosystems on the continent focused on pollutants such as nutrients (e.g., nitrogen, phosphorus), heavy metals and coliform bacteria 137. Comparatively, little research has been conducted on the impact of organic contaminants (i.e., pesticides, antibiotics, pharmaceuticals, endocrine disruptors, chemicals associated with oil and gas combustion) despite their reported importance globally. Contaminants enter aquatic systems from land-based sources such as wastewater treatment plants, livestock and crop production systems, animal and human health facilities and landfills. Biological and chemical processes in water and wastewater treatment systems have limited capacity to remove organic contaminants, leading them to persist in aquatic environments. The presence of organic contaminants in aquatic systems poses serious ecological and human health risks due to their potentially toxic, mutagenic (i.e., alteration of genetic material) and carcinogenic effects 137. Contaminants can impact aquatic ecosystems directly, influencing ecological processes such as biogeochemical cycles and trophic interactions. Although evidence on the impact of pollutants on aquatic populations is currently lacking globally, a few studies in Africa have documented intersex or sexual alteration in fish and amphibians species 137,156. Contamination of aquatic ecosystems may also have implications for food security and livelihoods since the successful reproduction and recruitment of fish is vital for stock maintenance. Furthermore, consumption of contaminated water or aquatic foods has the potential to negatively affect human health via toxic effects leading to genetic mutation and cancer 157. In addition, residual antimicrobial drugs that enter aquatic systems from farm waste may contribute to the development of antimicrobial resistant bacteria, which can spread to humans, livestock and wildlife through consumption of fish or water 137. Overall, there is a lack of information on the ecological and human health effects of organic contaminants pollutants in Africa. Published studies have focused on reporting the concentrations of organic contaminants in African aquatic systems and providing comparisons to local and international guidelines. In addition, the few studies available on African aquatic environments have focused on pesticides 158,159 and insecticides used for vector-borne disease control 160, resulting in major gaps in knowledge on the environmental risks associated with other synthetic organic compounds in Africa. The Natural Environment and Health in Africa Box 5: Human-wildlife conflict and poisoning Wildlife poisoning is rife in Africa and poses a serious threat to iconic African species such as lions, elephants, hyenas and vultures. Highly toxic pesticides are frequently used to poison wildlife and problem domestic animals and the motivations for this include conflict with predators that kill livestock and with crop- damaging animals, to eliminate vultures that act as wildlife sentinels when elephant poaching occurs, and to harvest animals for food (particularly birds and fish) and for spiritual or medicinal purposes 25,161. Because poisons kill indiscriminately, they devastate entire scavenger communities as well as the Vultures on a carcass intended target species, while also posing a serious environmental hazard. As keystone species, vultures represent fundamental components of ecosystems, providing important functional services, such as carcass decomposition and hence regulating numbers of other mammalian scavengers at carcasses, which are important reservoirs for a number of diseases including rabies 26. Through these mechanisms, vultures may regulate the risk of zoonotic diseases, thus playing an important role in the health of people and their livestock. In India, health care costs related to vulture declines due to poisoning by the veterinary drug diclofenac have been estimated at USD 1.5 billion annually due to increases in rabies transmission between humans and feral dogs (and other pathogens hosted by mammalian scavengers), providing an insight into the economic and health implications African countries may face as vultures decline 162. In June 2019, 537 vultures were killed in a single poisoning incident during their breeding season in Botswana, after poachers poisoned an elephant carcass in the north of the country. Poisoning of water sources (e.g., lakes, waterholes, rivers) to kill damage-causing animals such as elephants or to harvest fish is one of the most environmentally destructive practices, and has the potential to endanger not only wildlife, but also humans and their livestock. Tackling wildlife poisoning requires a multi-pronged approach that addresses the socio-economic drivers of poisoning, the lack of awareness about the dangers of poison use, and the criminal element whereby perpetrators are infrequently apprehended and even less frequently prosecuted or convicted. Steps are being taken to address the socio-economic drivers leading to wildlife poisoning, including initiatives to build predator- proof bomas (corrals), erecting electric fences to deter crop-raiding elephants and providing compensation for losses that are incurred. A few conservation organizations are engaged at the grass-roots level to create awareness about the dangers of using poisons to kill wildlife. The largest remaining gap is to improve analytically sound detection and capacity in wildlife toxicology, to expand the scientific capacity of wildlife authorities to better address local law enforcement. 29 The Natural Environment and Health in Africa Box 6: Gender, wild meat value chains and zoonotic spillover Wild meat harvesting, trade and consumption is widespread in Africa providing a source of livelihood and food as well as playing key sociocultural roles in several communities 163. However, harvesting and consumption of wildlife for nutritional, belief-based and medicinal purposes can present a significant risk for exposure to emerging zoonotic diseases in humans. Understanding how various socio-economic and cultural drivers influence the wild meat trade is critical to developing effective sustainable conservation-health interventions. The gender dimension of the wild meat value chain is an important consideration not only in the emergence and re-emergence of infectious zoonotic diseases but also in understanding their impact on conservation efforts. The wild meat value chain is highly gendered 146,164,165 with roles and responsibilities clearly defined, and to a large extent governed, by social norms in relation to masculine versus feminine roles as well as cultural sanctions. Roles within the wild meat value chain include methods of hunting, preparation of carcasses for transportation, transportation, cooking (fixing, burning, slicing and cooking), retailing and consumption146. Hunting is mainly conducted by men while women engage in trade as vendors, who also process bushmeat. Children, especially young boys, also play a role in hunting albeit to a lesser extent and mainly hunting small wild animals. Women are involved as traders - retailers, wholesalers, restaurant owners - who engage at the later stages of these value chains where they purchase bushmeat from hunters, transport it to various places sometimes out of their own villages, and engage in preparation of the animals for consumption 146,166. According to Akem & Pemunta 167, the highest risk of disease transmission occurs during the butchering of animals and food preparation which is mainly performed by women, hence placing them at highest risk of disease transmission. Gendered differences are also noted in preference and consumption of wild meat. Men consume more wild meat than women, a factor that is mediated by cultural taboos which prescribes and proscribe specific animals for different gender and age groups mainly adult women, young men and young women 166,168. Strong, evidence-based data linking the consumption and handling of wild meat to spillover of zoonotic pathogens is lacking. Circumstantial evidence suggests that at points (‘nodes’) along wild meat value chains, actors (men, women and children) exposure to zoonotic diseases occurs through various ways; hunting methods that result in scratches and bites, exposure to fur aerosols and blood from animals, cuts obtained while preparing the bush meat, and consumption of undercooked meat 165,169. Interestingly women appear to be at greater potential risk of exposing themselves to zoonotic pathogens through accidental self-cutting compared to men 146,167. Complex socio-economic and cultural factors drive the consumption and trade of wild meat, and ultimately determine zoonotic spillover risk. Gender- disaggregated data and analysis is important in designing risk mitigation measures and communicating behaviour change interventions in relation to zoonotic diseases using a One Health approach. Considering the socio-economic and cultural environment in which the wildlife trade and other environmentally linked health outcomes occur is critical to ensure public health-conservation intervention strategies are successful. Wild meat on skewers The Natural Environment and Health in Africa Box 7: The impact of invasive species on aspects of health Invasive alien species (IAS) are defined as alien or non-native species (which can include animals, plants and pathogens) whose introduction and/or spread threaten biological diversity 170. They can significantly impact human and animal health as illustrated by the rinderpest virus which spread from Asia to the rest of the world, causing major pandemics in livestock and wildlife in Africa 171. Invasive plants can also negatively impact health in Africa. For example, several invasive plants have been shown to promote vector-borne diseases such as malaria 153, and through changes in mosquito vector populations have the potential to impact the transmission of important arboviruses such as Rift Valley fever virus and West Nile virus 154. The invasive weed Parthenium hysterophorus can cause dermatitis and allergic respiratory problems in humans and animals 172. Invasive species can also influence health indirectly. The invasive mesquite tree from South Africa (Prosopis juliflora) now occupies millions of hectares across Africa and has eroded the natural resource base on which millions of people depend, leading to conflict as people compete for access to grazing land and water 170. Lack of grazing due to IAS can also drive human-wildlife conflict as communities drive their livestock into protected areas. Furthermore, IAS can negatively impact economic development. These effects can be direct as reported for the invasive cactus Opuntia stricta in eastern Africa which has led to economic losses due to impacts on livestock production 173. The indirect effects of IAS on economic growth include the negative impacts on tourism 174, hydro-electricity generation 175 and food security 170. Cattle grazing around the invasive cactus Opuntia stricta. 31 Climate change adaptation and mitigation Natural ecosystems can provide a major increased susceptibility to disease, changes in contribution towards climate change the distribution of disease vectors and their adaptation and mitigation but are also pathogens, and displacement of people and their acutely susceptible to the impacts of climate animals which can further promote spread of change. disease. Climate change also has the potential to promote armed conflict, resulting in ecosystem Through climate-mediated degradation of degradation, infectious disease outbreaks, and ecosystems (e.g., due to drought, flooding, fires, biodiversity loss (see Box 8). The impacts of conflict or overgrazing), climate change can drive climate change on agricultural production, many of the health outcomes already described invasive species and pollution can also reduce in Table 1. Changes in temperature, flooding and food and water security. drought can also have direct impacts on human and animal health, through heat stress and Reprinted from the American Public Health Association The Natural Environment and Health in Africa The potential impacts of climate change adaptation and mitigation strategies on health Strategy Health Implications Evidence Refs Geographic Scale Climate Disease surveillance, nature-friendly vector control methods, vaccination, Weak 65,176 Landscape, Regional change and maintenance of genetically diverse animal populations reduce the risk posed by geographic range shifts of vector-borne diseases adaptation Drought forecasting, improved sanitary practices and restoration of natural Moderate 140,177–179 Landscape, Regional watersheds reduces water-borne bacterial disease, pollutants, and algal blooms Habitat restoration, connectivity and human access to safe water reduces Weak 180 Landscape human-wildlife conflict and amplification and spillover of zoonotic pathogens during times of drought Selected breeding and diversified agricultural systems improve resilience Weak 67,132,179 Site of food and water security, nutrition, and livelihoods to extreme events Flood forecasting and fortifying sanitation systems reduces human and Moderate 67,181 182 Landscape, Regional animal exposure to water-borne disease, rodent-borne zoonotic pathogens, and pollutants. Flood mitigation from ecosystem services reduces the risk of associated Weak 67,181 Landscape, Regional infectious and non-infectious diseases Sustainable fisheries and aquaculture practices can buffer against extreme Weak 67 Landscape weather events and enhance food security and livelihoods Improves societal stability, reducing conflict and downstream impacts on Moderate 179 Regional, Global human and animal health Infectious disease control measures and animal welfare improvements Weak 133,183 Site, Global delivered by sustainable agriculture can reduce greenhouse gas emissions, while improving animal and human health Ecosystem Carbon sequestration helps to regulate climate change which has multiple Moderate 67 Landscape, Regional, conservation, impacts on human and animal health Global management Buffers against extreme weather events such as flooding, reducing the risk Moderate 67 Landscape and/or of associated infectious and non-infectious diseases restoration Improves the resilience of food systems to extreme events Moderate 67 Landscape, Regional Improves food and water security, reducing conflict and downstream Moderate 67,179 Regional, Global impacts on human and animal health Access to Improves access to healthcare, reducing burdens of infectious disease and Strong 184 Site, Landscape electricity and improving overall health and wellbeing clean cooking Reduces carbon emissions, reducing the effects of climate change and Strong 185,186 Global improving air quality Reduces deforestation, supporting all ecosystem services, nutrition, and Strong 65,176 Site, Landscape livelihoods Improves food safety, improving nutrition and mitigating against poverty Moderate 140,177–179 Landscape traps Reduce GHG Sustainable agricultural practices reduce emissions and improve the Strong 180 Landscape, Regional, emissions resilience of food systems Global Reduces the impacts of climate change on ecosystem health, supporting Strong 67,132,179 Landscape, Regional all ecosystem services and reducing the incursion of invasive species 33 The Natural Environment and Health in Africa Box 8: One Health, climate and armed conflict in Africa More than 90% of significant armed conflicts between 1950 and 2000 took place in countries encompassing biodiversity hotspots, with over 80% occurring directly within these hotspots 188. African biodiversity hotspots that have recently experienced conflict include the Cape Floristic Region; Coastal Forests of Eastern Africa; Eastern Afromontane; and Guinean Forests of West Africa. Despite some of the deadliest conflicts having ended (i.e., Biafran War in Nigeria in 1960s and 1970s, the Congo Wars and the Rwandan Genocide in the 1990s and the Ethiopian and Eritrean war in 1999-2000), the number of armed conflicts in Africa is projected to increase, due to a complex mix of factors including social and economic inequality, political factors, climate change and loss of ecosystem services (Figure 7). As an overarching driver of water and food scarcity and competition, and changing patterns of human migration, climate change can act as a ‘risk multiplier’ for armed conflict, and has been linked to violent conflict in several African countries 189. The effects of armed conflict on human, animal and ecosystem integrity are multifaceted. Direct impacts on human and animal health include loss of life due to military operations, displacement of people and their animals, interruption to food systems, and breakdown in human and animal healthcare systems, which can propagate outbreaks of infectious and non-infectious disease. Natural ecosystems are often occupied by armed groups due to their remoteness, where building materials and food are sourced through deforestation and bushmeat hunting thereby increasing opportunities for pathogen spillover between wildlife and people. Wildlife and extractive industries may also play a role for Governments and militias in raising financial or political support. High value wildlife products (such as ‘conflict ivory’) have financed conflicts throughout Central Africa 190, and gold mining, which can cause considerable environmental pollution, is common in areas under control of armed militias. Figure 7. Replicated from the Peace Research Institute Oslo159, showing changes in conflict types and battle- related deaths over time in Africa.  34 Nature positive finance Quantifying the benefits of the natural nutrient cycling, erosion control, pollination, and environment to human health has climate regulation are being depleted as a side traditionally been achieved via natural effect of global ‘progress,’ leading to the capital accounting 192. The concept of ‘natural unintended consequence of an overall decrease capital’ looks to place value on naturally in wealth among the poor and a failure to occurring systems, or ‘stocks,’ as assets to improve standards of living. This poses a health and the wider economy. These natural significant challenge to attaining poverty systems include geology, soil, air, water, and reduction and sustainable development goals biodiversity, and are the stocks from which across Africa. benefits to human health, welfare and the global economy (i.e., ecosystem services) flow. The COVID-19 pandemic highlights the links However, quantifying the value of natural between the health of the natural environment systems is a relatively new practice and at and humans and demands that the critical role of present does not adequately account for the ecosystems in supporting human health and substantial impact that global natural wellbeing must not be overlooked. Incorporating ecosystems have on human health. the value of disease regulation and disaster mitigation provided by ecosystem services must Throughout history, natural resources have long be an essential component of all future natural been perceived as ‘free’ in both commercial capital assessments, a requirement that has markets and policy structures, with exploitation, been underscored by the pandemic. Dobson et adaptation, and substitution widely encouraged al.197 attempted to quantify the benefits of 193. Fossil fuels, agriculture, and modern protecting ecosystems in relation to preventing plumbing are just a few examples of ways in the COVID-19 pandemic. The authors estimated which humans have exploited earth’s natural the global cost to (i) halve the rate of tropical stocks with little regard for the implications that deforestation, (ii) conduct disease surveillance depletion or contamination may have on wider programs for wildlife and domestic animals, and ecosystems services. These stocks and the (iii) stop illegal wildlife trade, and compared this services they support however, are critical to the to costs associated with the pandemic. The net economy, food security, social infrastructure, prevention costs of these actions were estimated leisure and tourism. In recognition of this, natural to be US$20-30 billion per year, which is capital accounting has evolved to address the substantially lower than the loss of at least US$5 valuation of these stocks and flows in an effort to trillion in GDP due to COVID-19 in 2020, not position policymakers to better understand the accounting for the impact on human lives. The dependence of economic development on the estimated value of applying these prevention continued function of natural resources and measures over 10 years equates to services. approximately 2% of the costs of the COVID-19 pandemic 42. In 1997 Costanza et al. 194,195 developed the first estimate for the value of ecosystem services, In addition to providing a buffer between humans globally which was later updated in 2014. and pathogens and acting as a countermeasure Grouping ecosystem goods (e.g., lumber, food) to disease emergence, the natural environment and services (e.g., water filtration, pollination) can support economic and social recovery together, they estimated the global value to efforts. Large-scale government stimulus average between USD $125 and $145 trillion packages aimed at spurring economic recovery annually in 2011. Indeed, when natural capital in the aftermath of the pandemic provide an was factored into national economy opportunity to design packages that assessments by the World Bank in 2018, it was simultaneously boost the economy and deliver found to be the largest contributor of wealth in positive environmental outcomes. Stimulus low-income countries (47% in 2014), accounting packages should integrate measures to reduce for more than one-quarter of wealth in lower- carbon emissions, protect biodiversity and the middle-income economies 196. Despite this, ecosystem services that underpin human health, natural capital assets that support ecosystem wellbeing and resilience to shocks like services such as water regulation and supply, pandemics. The Natural Environment and Health in Africa Integrating One Health into nature-positive finance Strategy Health Implications Evidence Refs Geographic Scale Valuing nature The COVID-19 pandemic highlights the links between the health of the ModerateWeak 42,192– Regional natural environment and humans and demands that the critical role of ecosystems in supporting human health and wellbeing must not be 195,198 overlooked. Incorporating the value of disease regulation and disaster mitigation provided by ecosystem services is essential in all future natural capital assessments. Building on the Stimulus packages should integrate measures to reduce carbon emissions, Moderate 42,198 Regional post-COVID to protect biodiversity and the ecosystem services that underpin human health and wellbeing and our resilience to shocks like pandemics. ‘Green and Just Recovery’ Plains zebra in Tsavo East National Park, Kenya The Natural Environment and Health in Africa Box 9: Natural capital accounting in Africa Natural capital is defined as ‘elements of nature that directly or indirectly produce value to people, including ecosystems, species, freshwater, land, minerals, the air and oceans’ 199. In most African countries, natural capital accounts for between 30% and 50% of total wealth however, in many of these countries the benefits of natural capital are not factored into total GDP 196. Failing to properly account for natural capital has led to the benefits derived from natural assets being over-exploited, causing an overall decrease in wealth and a failure to improve living standards. For instance, it is estimated that Africa loses approximately USD 195 billion of its natural capital annually via illicit financial flows, illegal mining and logging, illegal trade in wildlife, unregulated fishing, and environmental degradation, among others things 200. Many of these resources, once depleted, are slow to renew (e.g., timber) or non-renewable altogether, thus decreasing national GNP. Similarly, attempted replacement of depleted ecosystem services often results in undue financial burden beyond the cost of judicious and sustainable management of the natural resource 193. Therefore, by measuring and valuing the contribution of natural capital and ecosystem services, countries are better equipped to understand the repercussions of policy and investment choices. Natural capital accounting (NCA) – underpinned by the System of Environmental-Economic Accounts (SEEA) – is an umbrella term that describes efforts to use an accounting framework to systematically measure and report on stocks and flows of natural capital 201. NCA covers accounting for individual natural assets or resources, as well as accounting for ecosystem assets, biodiversity and ecosystem services. In Africa, NCA is increasingly used as an evidence-based policy making tool to increase sustainability and meet international commitments. In 2019, the first Africa Forum on Natural Capital Accounting was held in Kampala, Uganda, organised by the World Bank Wealth Accounting and the Valuation of Ecosystem Services (WAVES) programme, the Secretariat of the Gaborone Declaration for Sustainability in Africa (GDSA), and the United Nations Statistics Division (UNSD) 202. The forum brought together participants from 18 African countries and built on engagement started in a first meeting on NCA in Africa in 2016. Questionnaires completed at the two meetings demonstrated good progress on NCA in Africa and highlighted barriers to implementing NCA, including financial resources availability, lack of statistics/data for accounts, and lack of technical expertise (Figure 8). The forum found evidence of an increasing demand for NCA in Africa and a strong interest in working collaboratively to take this area of work forward including in the development of a Community of Practice that can contribute to mainstreaming NCA applications in Africa. Figure 8: Challenges faced in the implementation of NCA as captured by questionnaires administered in 2016 and 2019 by the United Nations Statistics Division (figure reprinted from the Africa Regional Natural Capital Accounting Policy Forum: Workshop Report and Next Steps168). Greening development Global demand for food, water and energy be asked to meet, relating to a wide range of is projected to increase by 35%, 40%, sustainability metrics, including respect for basic and 50% by 2030, respectively 203. Such human rights, worker health and safety, the increases are required to meet growing demand environmental impacts of production, community due to human population expansion while relations, land use planning and others’’ 206. The improving the livelihoods of people who are strong links between environmental degradation undernourished and do not have access to and human health as demonstrated in this report, electricity or clean water 204. As well as having support the need for disease risk to be direct impact on human health, resource scarcity incorporated into sustainability standards for can have indirect impacts on human health and infrastructure and extractives industry well-being by impacting the practices by which development. This can be illustrated with the humans utilize natural resources. Climate change example of deforestation for commodity further impacts resource security, reducing production and malaria burdens. Deforestation agricultural yields and increasing vector-borne, linked to the production of commodities such as water and food-borne diseases burdens10. The timber, soybean, beef, palm oil, tobacco, cocoa, sustainable management of natural capital coffee, and cotton is driven by demand in assets such as agricultural land, forests and developed countries 207. As well as threatening protected areas is required to meet both the biodiversity and ecosystem health, the immediate and long-term needs for food, water associated changes in tropical forest landscapes and energy security in Africa. The water-energy- can also increase malaria risk for local food (WEF) nexus which assesses synergies, communities 208. The people at greatest risk of conflicts and trade-offs that arise from how the disease are the ones exposed to landscape different resources are managed (i.e., water for transformation and poignantly, are likely to food and food for water, energy for water and realise the least economic benefit from these water for energy, and food for energy and energy activities 209. Chaves et al. 208 estimated that for food) can be used to identify vulnerabilities 20% of the malaria risk in deforestation hotspots and target interventions with cutting-edge green is driven by the international trade of technology to improve resilience and health deforestation-implicated export commodities. outcomes for communities 205. Linking the risk of infectious (e.g., malaria) and non-infectious diseases (e.g., cancer associated Sustainability standards also known as Voluntary with pollution exposure) for local communities to Sustainability Standards (VSS) are private final consumers of commodities will help to standards that "producers, traders, support demand-side policy measures and will manufacturers, retailers or service providers may benefit both human and ecosystem health. The potential impacts of greening development strategies on health Strategy Health Implications Evidence Refs Geographic Scale Develop Sustainable management of natural capital assets is required to meet both the Moderate 204,205 Regional sustainable food, immediate and long-term needs for food, water, and energy security in Africa. Assessing the synergies, conflicts and trade-offs that arise from how these water and energy different resources are managed can be used to identify vulnerabilities and systems target interventions to improve the health and resilience of communities. Green and blue Unplanned urbanisation, which is characteristic of many rapidly growing cities Strong 210,215,218 Local urban planning in Africa, poses numerous health risks to people, animals and ecosystems. With appropriate blue and green urban development planning, these risks can be addressed. Engage with There is a need for the risk of disease exposure (infectious and non- None Regional infrastructure and communicable) to be incorporated into sustainability standards for infrastructure and extractives industry development. extractives industry development Address market Linking the risk of disease for local communities to final consumers of Weak 208 Global drivers commodities would help to support demand-side policy measures, benefiting both human and ecosystem health. The Natural Environment and Health in Africa Box 10: Rapid urban development, ecology and health We live in a rapidly urbanizing world. Today, more than half of the human race live in cities, and this number is set to continue increasing, as people migrate to urban areas in search of higher standards of living. Through pollination, seed-dispersal, buffering against the invasion of exotic wildlife species, and improving human quality of life, urban biodiversity can improve the health and livelihoods of people living in urban environments. Careful planning is required to ensure that detrimental impacts of urban development on the natural environment and human health are A low-income settlement overlooking the Nairobi river in Nairobi, Kenya identified and addressed. For many countries in Africa, efforts to constrain the negative impacts of urban development through city planning are outpaced by high rates of urban migration. Encroachment into natural habitats, poor sanitation, informal livestock-keeping and animal trade in these unplanned urban environments pose a threat to biodiversity whilst acting as a crucible for interactions between humans, animals and their pathogens3. Native species that play important roles in ecosystems are lost, allowing wildlife that co-exist with humans and are more competent hosts of zoonotic pathogens – such as rodents – to thrive 98,210,211. This is troubling because these species are more competent hosts for zoonotic pathogens. Evidence shows that the public health risks posed by biodiversity loss, exposure to animal-borne diseases, and lack of medical care to urban populations are not equally distributed, and disproportionately impact the poor 93,212–214. Growth in per capita GDP and efforts that focus on improving urban health and living conditions in African cities present a significant opportunity to rehabilitate, expand and redistribute urban green space 210. Not only could this improve individual health and prosperity (since non-communicable diseases such as allergic and psychological conditions have been associated with lower urban biodiversity 214, and property value are typically higher close to urban green spaces) but it would also mitigate broader environmental challenges that cities in the tropics face, such as flooding, high ambient temperatures and pollution. However, for blue and green urban development to be effectively implemented – particularly for cities undergoing rapid urban change – methodological frameworks that incorporate indicators for ecosystem services, social equality and health are needed 215. Such frameworks have yet to be developed for rapidly urbanizing cities in the tropics but are urgently required since many African cities set to double in size within the next thirty years. Inspiration could be drawn from existing frameworks for green urban design and urban biodiversity management, such as those recently proposed by Lambert and Donihue 216 and Puchol-salort et al. 217 39 An engaged society Supporting the engagement of African It is equally important for Africa to have a diverse societies, and in particular Africa’s youth, academic and professional workforce that is is critical to achieving conservation and aware and actively engaged in understanding health outcomes and central to charting a and addressing the connections between the sustainable future for the African continent. natural environment and health, and representing Formal education and extra-curricular activities these connections at the highest levels of can be used as a tool for people to link their national and regional policymaking. These health to the natural environment through activities are crucial to shaping Africa’s current experience and practice, so that both are valued and future One Health leaders. While Africa as important cornerstone of prosperity and already has well-established One Health economic development. Targeting this academic and training networks (such as the engagement around One Health across African Africa One Health University Network – society – from indigenous peoples (many of AFROHUN), and government agencies invested whom already have strong connections with the in One Health (such as the Government of environment and health) and local communities Kenya’s Zoonotic Disease Unit), topics of focus to urban dwellers – is crucial to achieving need to extend beyond veterinary public health improved health outcomes, since the links to include ecology, ecosystem management and between people’s health and the natural conservation. environment vary greatly, and because encouraging behavioural change is a major part of the solution. The potential impacts of engaging societies and learning institutions on the connections between the natural environment and health Strategy Health Implications Evidence Refs Geographic Scale Build both Integrating mixed methods that acknowledge indigenous knowledge and raise Strong 67,219 Site, Landscape awareness and awareness about site-specific connections between ecosystems, the natural environment and human and animal health into community engagement efforts capacity of youth is crucial to engage those who are most likely to see the immediate impacts of groups to engage in ecosystem change on their health and livelihoods. This is also key to achieving behavioural changes that could mitigate health risks posed by infectious conservation disease, pollutants, and agricultural practices. Supporting and encouraging grassroots extra-curricular school and university Strong 219,220 Site, Landscape, networks that are engaged in i) conservation, to broaden their networks to Regional include health, or ii) public health, to broaden their networks to include the natural environment, would promote local community efforts, educational events, and small-scale research projects on topics relating to One Health, Ecosystem Health and Planetary Health. This would facilitate bottom-up advocacy, solutions, and initiatives, while ensuring that the next generation is engaged in these topics. Actively engage Through integration of One Health into school curriculum, children would Strong 220 Site, Landscape with learning develop an innate appreciation of the impact of the natural environment and animals on human health, while gaining stronger skills around scientific enquiry institutions in target and critical thinking. countries and landscapes to Most existing university training and advocacy networks for One Health in Strong 221–223 Regional transform their Africa (e.g., AFROHUN) focus on veterinary public health. Broadening these institutions into networks to include the impacts of the natural environment on health outcomes, and supporting integration of academic stakeholders in relevant centres of fields, would necessarily place the natural environment at the centre of many sustainability of the continent’s One Health training and research strategies. 40 The Natural Environment and Health in Africa Box 11: Participatory approaches to engage and empower communities in addressing linkages between the natural environment, conservation and their health. Environmental degradation causes disproportionate harm to Africa’s low-income rural populations, who often live in close association with and rely on biodiversity and natural ecosystems 224,225. For example, between 50 and 200 million nomadic pastoralists inhabit sub-Saharan African drylands, subsisting on herds of livestock that move between water sources and seasonal grazing areas 226. The mobility necessitated by livestock management practices have led to the systematic marginalization of pastoralists and their animals 227. Exclusion from institutional resources (such as education and healthcare) that would otherwise be available to support communities threatens public health and biodiversity conservation efforts by limiting the ability of authorities and conservationists to identify and respond to the threats posed to human, animal and ecosystem health when they occur, or to introduce measures that reduce the occurrence of these events as they increase in the future. Marginalization is not necessarily limited to remote, rural communities; social and economic exclusion in urban settings (e.g., characteristic of informal settlements) can have an equally important impact on health and wellbeing 228. Owing to the strong influence that gender and socio-economic status have on the impact of environmental change on people’s health and livelihoods, and the acceptance and suitability of strategies to address this, there is an acceptance of the need to engage and empower marginalized communities to identify and solve the health and environmental challenges that they face with participatory approaches 229–231. These methods generally take the form of guided conversations, visualization methods and numerical recordings through ranking and scoring methods (see Cately et al. 232 for an in-depth review with specific examples of how these approaches are being applied to epidemiology in Africa). Using participatory approaches much can be learnt from traditional and current knowledge that these communities possess to improve context-specific understanding of the connections between socioecological systems and human health, and to inform locally effective strategies that improve health and support biodiversity. For these strategies to be effective over the longer-term, local ownership of health and natural resource management is crucial. To achieve this, efforts must focus on engaging communities at multiple systems levels, for example: 1. Working at the level of individual households to understand behavioural and environmental risk factors for human health outcomes, and their drivers 233. 2. Using participatory mapping and household and community levels to understand patterns of interaction between people and their animals and the environment – e.g., transhumance, harvesting of flora and fauna 234–236. 3. Targeting educational messages that promote less risky activities and behavioural change at specific audiences and/or sectors who operate at priority interfaces between the natural environment and health (e.g., hunters, mining, trade/markets) 233. 4. Using social and educational networks to raise awareness and mobilize community action towards addressing issues that affect all community members. 5. Engaging local and national institutions to support structural change that makes healthcare more accessible to marginalized communities 237. The Natural Environment and Health in Africa 42 Key challenges and recommendations for applying One Health to address environmental and health crises in Africa To galvanize action around the threats that environmental degradation and biodiversity loss pose to societies in Africa and further afield, it is crucial for leaders to signal their support for the natural environment to be at the heart of sustainable development and global health policy moving forward. In general, this report finds a striking lack of evidence for the mechanisms by which environmental degradation endangers human health, although this is not unique to the African continent. Broad partnerships between the public and private sectors will be vital to address evidence gaps, accurately measure the impact of environmental degradation on health, and engage with and educate the public on the importance of the natural world to health. Without sound scientific evidence and real-world success stories, communicating the importance of integrating protection of the natural world into global health policies to decision makers, so that solutions can be designed and tested, remains a significant challenge. We end this report by identifying four key challenges that must be overcome for the natural environment to be appropriately valued for the role it plays in supporting health on the Africa continent, and present recommendations as to how they could be addressed. Farmland at the foot of the Virunga mountains in Rwanda Challenge 1: Lack of evidence for the mechanisms linking the natural environment to human and animal health Issue 1: Geographic disparity in Very few studies focus on the linkages between research efforts limit scientist’s land use, host ecology and disease (only a abilities to study the impacts of handful of papers from this review; Lassa Fever Virus and Ebola Virus in West Africa 59,238, environment degradation on health leptospirosis in Tanzania 239, bartonellosis in across Africa. Kenya17, and antimicrobial resistant Escherichia coli in Nairobi 240). Instead, most Africa-based Fragmented research efforts make it difficult to epidemiological studies conducted at the study processes that occur across landscapes wildlife-livestock-human interface focus on and assess the risks faced by people who live in describing patterns of infection in different host different settings. Large parts of south-western populations across these interfaces. and central Africa and the Sahel – all areas where Epidemiological studies and disease detection expanding human populations inhabit efforts are essential for monitoring disease risk at landscapes that are undergoing considerable wildlife-livestock-human interfaces and environmental change and are known to harbour establishing site-specific mitigation measures zoonoses – are underrepresented or missing (such as vaccination or physical separation via from research efforts. Differing levels of fencing). In addition, an understanding of the investment in research activities and research mechanisms listed above is of fundamental infrastructure probably have their roots in importance for devising broader scale measures historical inequalities (such as colonialization) that prevent humans and their livestock acquiring and economic and political instability. Colonial pathogens from wildlife, and wildlife acquiring legacies continue to shape the geopolitics of pathogens from humans and their livestock. In research in Africa and therefore play a role in recognition of this, “land use induced spillover” maintaining geographic biases. has recently been proposed as an explicit field of scientific enquiry and a priority for land use policy and management decisions 62. Issue 2: Lack of evidence on the mechanisms by which land use Specific knowledge gaps that need be change impacts disease transmission addressed to mitigate land use-induced spillover between wildlife, livestock, and and reverse biodiversity loss include: people. • A deeper understanding of the broad cultural and demographic drivers of the wildlife trade Strong, evidence-based data linking the role of across the African continent, how this human incursions into wildlife habitat to direct influences supply and demand, measurement contact with wildlife and zoonotic and of the specific hazards posed by the trade to anthroponotic disease emergence is lacking. For humans, and implications for control. For the most part, our understanding of the direct example, the hazard posed by different health risks posed by consumption and trade of pathogens remains poorly quantified and there wild meat in Africa is informed by the is only anecdotal evidence that urban demand perceptions of those involved, and assumptions plays a major role in East Africa’s wild meat based on pathogens that are known to be trade, even though cities could be key places circulating in wildlife being traded. The broader in which to target control measures. sociological drivers of wildlife trade and consumption in different parts of Africa (such as • The mechanisms linking climate change and urbanization), and the health implications of the land use change (deforestation, and habitat trade in live wild animals from Africa to Europe, conversion for agricultural practices) to also remain under-studied. physiological stress, immunity, and infection in 43 The Natural Environment and Health in Africa wildlife, with a particular focus on species that - Evidence for the impact of pesticides and are considered important reservoirs for heavy metals from agrochemical use and disease (such as bats, rodents and non- human-wildlife conflict on terrestrial and human primates). In a recent study, aquatic biodiversity, and how this impacts researchers showed that losses of body ecosystem services that regulate condition in fruit-dependent elephants over a infectious disease (e.g., the impact of ten-year period in Gabon was correlated with trophic collapse on infectious disease a long-term collapse in fruit availability, linked dynamics – scavenger declines are a good to climate change 64. Studies matching long- example). term ecological datasets with monitoring of - Evidence for win-win scenarios, whereby health indicators in keystone species are sustainable practices provide a positive urgently required to study the mechanisms impact on food security while reducing that link ecosystem change to wildlife health. disease burdens and supporting ecological resilience. For example, habitat Issue 3: Lack of evidence on the restoration and sustainable harvesting of broader impacts of biodiversity loss river prawns in riverine ecosystems in on human health. Senegal reduced human schistosomiasis prevalence (by regulating snail host populations) while also benefiting local Biodiversity loss emerged as a central food security 66. component in this review and the systems maps that accompany it. Despite there being evidence • Evidence for the impact of green urban in other regions of the world 8, there is little development in African cities on human health empirical evidence in an African context for the (e.g., physical, and mental health, income- impact of biodiversity loss on human health and related health inequalities) 241,242. ecosystem services that regulate health outcomes. This is an area of great importance given current and predicted rates of biodiversity Issue 4: The impact of efforts to decline, and therefore requires further research. support conservation, health and Gaps include: livelihoods by returning keystone • The direct impacts of biodiversity loss on species to natural ecosystems often burdens of non-infectious disease in people go unmeasured. across African societies (e.g., immunology, allergy, mental health, and spiritual health). Scientific monitoring for the intended impact of • Global patterns of pollinator loss are assumed wildlife translocations on biodiversity to apply on the African continent, but there is conservation, ecosystem function and human very little evidence to support this, or measureP rotheecaltthi oannd liovefli hoods is crucial to avoid negative impacts oPf pollinator declines on the outcomes, justify prudent use of limited funds, continent’s rfooodm syostteimnsg (a nd therefore Critiacnad lc ritically assess whether these approaches nutrition aSndu lsivetlaihionodas)b. ly achieve improvements in biodiversity • The effecMts oaf snuastagineabdle agricultural on Biodciovneserrvsaititoyn and human health and wellbeing. biodiversity nd ecosystem services relating to However, the impacts of many translocations health. This knowledge Areas that, withL thae ngrdowsincga dp is eresquired to ensure that take place in Africa remain unmeasured. emand of food due to human population growth and the negative Issue 5: Lack of evidence on the far- impacts of climate change on food security, food systems have as little negative impact on reaching impacts of invasive species biodiversity and the natural environment as of animal and plant on human health. possible without sacrificing food security. Specific gaps in linking sustainable agricultural Like biodiversity loss, invasive alien species practices to health include: Climate Chanegmeer ged as a central component of the review, and accompanying systems maps, but due to a Adaptation and Mitigation 44 A S no Ec nie gt ay ged ing n me nt Gre e elo p De v The Natural Environment and Health in Africa lack of empirical research it is difficult to mosquitoes. Despite this, there are significant determine their true impact on human and animal knowledge gaps for how the natural world health. This lack of evidence applies at a global contributes to the regulation of disease globally scale, however within an African context, specific and how these overlap with ecosystem gaps include: interactions 67. In an African context there are significant knowledge gaps on the role of • The effects of invasive insects, mammals and ecosystems in mitigating or reducing vulnerability plants on biodiversity, infectious disease, to disasters 67 and how to sufficiently quantify human-wildlife conflict and food security. regulating services that ecosystems provide • Forecasting, and identification of high risk and (e.g., climate regulation, air quality, flood priority landscapes and interfaces where regulation, water purification, pollination, invasive species could have the greatest biological control, disease regulation). In impact on biodiversity, infectious disease, particular, information on the resilience that human-wildlife conflict and food security. ecosystem services provide to natural disasters and links between flood mitigation and reduction Issue 6: Lack of evidence on the in infectious diseases (e.g., vector-borne and impacts of unsustainable fisheries water-borne diseases) are absent. Compared to practices on ecosystem health. evidence for Europe, the number of published studies on the valuation of ecosystem services in Africa is relatively low, with the majority of Unsustainable fishing practices and climate studies conducted in Southern and East Africa change have negative impacts on ecosystem 67. health, food security and livelihoods, particularly impacting local fishing communities. Despite the importance of this issue, this review found little Issue 8: Limited evidence of the information on the extent of overfishing in Africa. impacts of humanitarian crises A 2016 IUCN report found identified a need for through a One Health lens research to better quantify the impacts of local, national and regional fishery efforts on targeted Despite the wide-reaching impacts of and nontargeted species 243. In addition, studies humanitarian crises on the natural environment, that consider the effects of pollutants (e.g., human and animal health, national and heavy metals, organic chemicals) on fisheries international agencies rarely adopt a One Health and aquaculture have focused on food safety but approach when responding to global overlooked impacts on ecosystem health and humanitarian crises. Instead, responses tend to how this may risk food security. For example, the be anthropocentric with a focus on operations, effects of pollutants on the trophic structure of logistics, shelter, nutrition, water and public food webs could negatively impact the health and sanitation. Pro erly evaluating the sustainability of fisheries, wildlife and human context-specific impacts that these crises have health via the toxic effects of pollutants, and Protoenc thtei onantu roal fe nvironment, and the immediate nutrition andP lirvoelimhooodst.i nLagck of environmental and longer-term impacts on human and monitoring dSauta sint Aafriinca’s coastal regions also Critieccaosly stem health is crucial to ensure that impacts the ability to perafobrml yen vironmental Biodeicvoelogriscailt ryes ilience and ecosystem services are impact asseMssmaennta fogr ededve lopment projects in Areamsaintained during crises and therefore able to the region 2L44.a ndscapes support societal recovery in the long-term. Issue 7: Lack of evidence on the regulating services provided by Recommendations: ecosystems in Africa. 1. Efforts should be made to identify The Millennium Ecosystem Assessment 50 recognizes that ecosystems can regulate disease research priorities and mobilize burdens by influencing the abunCdalnicme oaf htuem Can hanrgeeso urces to establish coordinated pathogens, and disease vectorsA, sducah past ation anedxp erimental and field studies that Mitigation 45 A S no Ec nie gt ay ged ng t eni n e pm e Gr eve lo D The Natural Environment and Health in Africa provide mechanistic and causal between science and measures that substantially inference on the impacts of reduce the risks of zoonotic spillover as a result environmental degradation and of the wildlife trade. Engagement with coordinated efforts in this way will help align biodiversity loss on health. research priorities and promote evidence-based advocacy at national and regional scales. African institutions should be at the forefront of these efforts, which would also help to support 4. Promote interdisciplinary scientific decolonialization and balance the collaborations between researchers geopolitics of health research on the continent. and natural resource managers so 2. Once research priorities have been that wildlife translocations are guided determined, cross-scale, long-term and accompanied by pre- and post- initiatives could be leveraged to translocation monitoring of address critical evidence gaps linking physiological, ecological and environmental degradation and anthropological indicators. biodiversity loss to human, animal and Engaging communities in these processes can ecosystem health. be extremely successful as means of fostering local support. For example, existing conservation and public health activities that span land and seascapes 5. Engage with humanitarian actors to (e.g., WWF’s network and Demographic and develop methodological frameworks Health Surveys Program sites) could be leveraged as platforms within which to establish for conducting environmental impact sentinel sites, where collection of ecological, assessments during humanitarian epidemiological and sociological data are crises and determine how best to standardized over time and at spatial scales that integrate environmental concerns are appropriate for understanding the ecological processes that determine health outcomes (i.e., within water, food and sanitation across landscapes that may be experiencing provisioning activities. different intensities of ecological change). At these sites, efforts should also focus on Humanitarian crises include those resulting from integrating indigenous and localised knowledge political unrest, armed conflict, natural disasters and expertise to better understand connections (such as drought and flooding), and outbreaks of between human health and the natural infectious diseases in humans and livestock. environment, and increase the inclusivity of Protection of policy formuPlarteod musiongt tihnisg e vidence. 245 Critical 3. OrganiSzautisontas iwnhaobsely w ork relates Biodiversity to the wilMdliafen taragde din Africa should engage wLitahn gdlosbcala epffeorsts to better Areas understand and address health risks associated with these activities. For example, the recently established International Alliance against Health Risks in Wildlife Trade (https://alliance-health- wildlife.org/) aims to enhance awareness, knowledge and policies to narroCw tlhiem gaapt e Change Adaptation and Mitigation 46 A S no Ec nie gt ay ged g nin me nt Gre e lop De ve Challenge 2: Absence of metrics and indicators with which to measure and value the impact of the natural environment on health Issue 1: Practitioners and decision- Issue 3: While the economics of makers lack standardized ways of pandemic prevention have been laid measuring and therefore assessing out by scientists, the natural the most important relationships environment’s broader role in between environmental change and supporting health remains unvalued, human health. and absent from natural capital frameworks. Robust metrics are necessary for public and private-sector decision makers to estimate and Metrics and indicators are required to support monitor their impacts on the natural environment the private and public sectors in assigning and health, and to test and scale solutions. economic value to the role that healthy Accurate measurements are also critical for ecosystems play in sustaining human health, identifying appropriate indicators that can be allowing returns on investment in ecosystems to used to monitor changes in environmental be directly linked to human health and economic conditions and associated health outcomes over growth. In this way, economic value can be time. placed on the different components of health offered by ecosystems (e.g., food security, water Issue 2: Decision-makers lack security, buffer to natural disasters), allowing indicators and ecosystem health corporations and policy makers to integrate health risks into their investment and policy assessment tools, that are capable of decisions. monitoring the impact of ecosystem change on human health. To determine whether ecosystems are being Recommendations: appropriately managed and sustainably used in a way that maximises positive health outcomes, it 1. Efforts should focus on developing is essential for the status and trends of a standardized metrics catalogue that ecosystem services that support health to be consists of data that can be used to accurately measured over time. This could be achieved using indicators that convey measure key components of information on the benefits that sustainable environmental change and human and practices that limit environmental change offer animal health, and composite through regulating infectious disease and other measures for the impacts of negative health outcomes. These indicators are required to monitor progress in implementing environmental change on health. sustainable development practices that maximize positive health outcomes, These metrics must include valuation of whole communicate the importance and impact of functioning [biodiverse] ecosystems and avoid environmental degradation and biodiversity loss placing value on single inputs, accounting for on health to policymakers, and to engage reliance of multiple environmental functions to consumers on the environmental impacts of their support individual ecosystem services. While purchases on health. Such indicators would offer some metrics linking the natural environment and a crucial interface between science, policy and health in Western society have been proposed consumers. (e.g., https://valuing-nature.net/demystifying- health-metrics-1), these do little to address the 47 The Natural Environment and Health in Africa very different set of environmental drivers influencing health in the tropics. An initial priority for substantiating measures of ecosystem value pertaining to health should be the development of standardized metrics that permit measurement of disease burden across species. Additionally, with increased global interconnectedness, a framework for the quantification of different impacts felt locally and regionally as well as worldwide must be developed. 2. Once metrics have been developed, a clearly defined framework for monitoring changes in environmental conditions and associated health outcomes is required, consisting of goals, targets and indicators. 3. The public and private sectors should come together to develop One Health investment roadmaps that connect ecological measures that improve health outcomes to their financial asset classes, as well as to corporations that are investing in natural capital valuation. If linked to global monetary and non-monetary benchmarks for human health (e.g., Disability Adjusted Life Years (DALYs)), metrics and indicators would allow returns on investment in ecosystems to be directly linked to human health and economic development. 4. Metrics and indicators should be Protection of incorporaPterdo imnto tvionlugn tary Critical sustainabSiluitys sttaaindaabrdlsy ( VSS). Biodiversity Many organMizataionnsa agree addo pting these Areas standards aLs paanrt dofs thceiar epffeorst to reduce the negative impacts of commodity production and conserve the world’s biological diversity246. The incorporation of DALYs and other metrics of disease burden both in humans and domesticated (farmed) animals into sustainability standards would connect sustainable management practices in the agricultural, fishing, forestry, mining and textile produCctlioimn seacttoers Change that support positive human health outcomes through maintaining ecosystem Aintdegaritpy, ttoa tion and consumers. Mitigation NASA imagery of Guinea-Bissau (image credit rawpixel.com) A S no Ec nie gt ay ged ing ent en pm Gre elov De Challenge 3: Loss of awareness and knowledge across African society for the deep connections between the natural environment and human health Issue 1: Connections between the who live in closest association with natural world and human health are biodiversity and natural ecosystems. complex and highly variable, making it Engaging and working in collaboration with rural difficult to communicate the broad communities who rely on natural ecosystems for value of the natural environment to their wellbeing and livelihoods to support them in protecting ecosystem function for their health, is health, to civil society. an important way to communicate risk and provide incentives to address behaviours and Global interest around the origins of the practices that can put people at risk. One Health COVID-19 pandemic, and growing concern for and conservation messages integrated with other threats such as biodiversity loss and traditional knowledge can be built from the climate change, provide an important bottom-up within communities – for example, by opportunity to connect with Africa’s civil society working with youth within schools (or through on the connections between health, society and community initiatives for indigenous peoples) to the natural environment. assess knowledge gaps, implement behavioural interventions that are passed onto their peers, Issue 2: Intensive agricultural and run social media campaigns. development, extractive industries, urbanization and the exclusion of local Issue 4: Africa’s One Health education communities from conservation and and academic networks focus on development programs contribute zoonotic disease, and lack towards people losing their contributions from practitioners connection with the natural working in ecological disciplines such environment. as conservation and biodiversity. Human population expansion and the associated The Independent Global Commission on increase in deforestation, urbanization and Education for Health Professionals for the 21st agricultural expansion are leading people to Century has identified the need for advanced, disengage from their historical relationships with interdisciplinary education to address complex the natural environment (which is particularly health challenges in an era of environmental strong in Africa). Indigenous communities such change as a priority 247. While educational efforts as nomadic pastoralists, forest dwellers, and the that bridge traditionally siloed health professions San, who have long managed ecosystems for such as human and veterinary medicine are their benefit and the benefit of wildlife are often increasingly being adopted (e.g., Africa One excluded from conservation efforts, and Health University Network (AFROHUN) 248), many frequently lose access to their land as a result. fail to fully address the socio-environmental Traditional knowledge that these communities contexts within which human and animal health possess to mitigate health risks may be lost as a outcomes are set, and few offer students the result. opportunity to develop advanced, transdisciplinary research skills in One Health Issue 3: Health risks cause that fully incorporate the natural environment, or consider health threats that extend beyond disproportionate harm to Africa’s infectious disease. poorest and most rural populations, 49 The Natural Environment and Health in Africa 50 Recommendations: This is required to strengthen national competencies in evaluating and tackling the 1. Advocacy groups should engage escalating health risks posed by the degradation networks of supporters on the African of the natural world, as professionals trained continent, who are already engaged in through these programs move into science and environmental concerns, and leverage practice, or advocate policy. this as a platform on which to • Extra-curriculum and youth-based ecosystem advocate for the importance of the health advocacy networks should be natural environment in supporting developed amongst communities inhabiting human health to the general public priority landscapes, engaging members of the public, and leading to educational events and who may have become distanced small-scale research projects on topics from historic understanding of the relating to the natural environment and health. interconnections between the natural • Educational programs and resources should environment and human health. be developed on the connections between the natural environment and health within secondary education systems. 2. Indigenous and rural communities • Existing One Health university networks such should be recognized as stewards of as AFROHUN should increase representation the natural environment, and of the natural environment in their academic and professional networks, and look beyond supported to play an active role in infectious diseases and AMR to non- natural resource management. Their communicable disease, pollution, invasive knowledge should be integrated into species and food security. solutions aimed at improving health. These activities would put African society in a strong position to raise 3. Stakeholders working in the global awareness for the connections environmental, public health and between the natural environment and animal health sectors should engage human health. with and broaden educational networks to provide more in-depth professional training on the environmental and ecological Community engagement components of health. on emerging zoonoses with pastoralists in Kenya Challenge 4: The connections between natural environment and health are rarely factored into public health or sustainable development policy in Africa Issue 1: Public health policy focuses Issue 3: Guidelines for incorporating on the links between public and health outcomes linked to the veterinary health environment into sustainable development frameworks are lacking. In Africa, efforts to integrate One Health into public health policy have mostly centered on veterinary and public health activities 249 – with particular focus on forecasting and control of the Recommendations: risks posed by zoonotic disease in production animals (and to a limited extent wildlife). There is 1. Establish mechanisms by which a need for policy to adequately consider and evidence can be effectively presented ‘price in’ the importance of ecosystems in to public health policy makers. promoting health, and the negative effects that their disruption can have on human and animal health. The public health sector in Africa has an It is crucial that scientific evidence, and reliable opportunity to reform health systems so that they metrics and indicators and openly available and integrate a One Health framework and move easily accessible to decision-makers, so that away from the inflexible, established and siloed they can make evidence-based policy decisions. health systems that are commonplace in the Global North. 2. Establish multi-sectoral platforms to facilitate cooperation and Issue 2: Resource allocation and the coordination, and allow decision- formation of partnerships to improve makers to engage stakeholders health are biased towards vertical, working at the interface between the disease-specific approaches. natural environment and human health to test and scale interventions. Donor funding for health is primarily designed to address high-visibility, single-issue topics, often aligned with specific issues or diseases. By Such platforms will need to operate at different promoting specific health outcomes rather than scales, at the global, regional, national and common drivers, this approach hinders formation community levels. of the interdisciplinary partnerships that are required to tackle complex, multi-pronged health The following topics could be regarded as a challenges that emerge from environmental priority: change. For instance, most national public health authorities that have adopted a One Health • Biosecurity measures that integrate across the approach logically follow a disease-specific environment, agricultural and human health approach, but this limits their ability to sectors, and include specific measures to appreciate and address the common drivers that address unregulated wildlife trade and land- underly these diseases and health more broadly. use change. 51 The Natural Environment and Health in Africa 52 • Disaster response strategies that include capacity to review and address the impact of humanitarian crises on ecosystem health and function in the short, medium and long-term. • Post-COVID stimulus packages that deliver positive environmental outcomes via the integration of measures to reduce carbon emissions, protect biodiversity, support the ecosystem services that underpin human health, wellbeing and resilience to public health emergencies. 2. 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The Natural Environment and Health in Africa 62 Appendix Systematic literature search d’Ivoire” OR Djibouti OR “Equatorial Guinea” OR Egypt OR Eritrea OR Ethiopia OR Gabon OR methods Gambia OR Ghana OR Guinea OR “Guinea- Bissau” OR Kenya OR “Kingdom of Lesotho” A systematic literature review of peer-reviewed OR Liberia OR Libya OR Madagascar OR publications was performed featuring components Malawi OR Mali OR Mauritania OR Mauritius OR of One Health, EcoHealth or Planetary Health in Morocco OR Mozambique OR Namibia OR Africa, conforming to the PRISMA guidelines. Niger OR Nigeria OR Rwanda OR Saharawi OR Briefly, this involved the following steps: “Sao Tome and Principe” OR Senegal OR Seychelles OR “Sierra Leone” OR Somalia OR 1. An initial broad-level search using the string “South Africa” OR “South Sudan” OR Sudan OR “one health” AND Africa in PubMed, Web of Swaziland OR Tanzania OR Togo OR Tunisia OR Science, and ProQuest, with a date restriction of Uganda OR Zambia OR Zimbabwe) 2003. n=436 article abstracts were screened according to a set of criteria aimed at filtering n=1,010 article abstracts were screened according irrelevant articles. n=317 were carried forward. to a set of criteria aimed at filtering irrelevant Limiting the search term to One Health resulted articles, and duplicates from the first review were in a heavy bias towards veterinary medicine and removed. n=662 were carried forward. A combined zoonoses. As such a decision was made to total of 971 articles were included in the final conduct a broader but more targeted search. database. 2. The targeted search used the following string in System dynamics model Web of Science, with a date restriction of 2003: (“land use change" OR "land use change" OR methods biodiversity OR “climate change” OR “wildlife- livestock interface” OR “livestock-wildlife interface” OR “livestock-wildlife-human Positive relationships were drawn for components interface” OR “wildlife-livestock-human that increase or decrease in the same direction, and interface” OR “wildlife-human-livestock negative relationships were used to indicate when interface” OR “human-livestock-wildlife factors move in opposite directions. Positive or interface" OR “human-wildlife-livestock negative relationships between components were interface” OR “livestock-human-wildlife only included where there was evidence that a interface” OR “wildlife-human interface” OR research study had used empirical data from Africa “human-wildlife interface” OR marine OR to identify a relationship (causal or not) and infer aquatic OR (livelihoods AND ecosystem) OR directionality. This information was also extracted (culture AND ecosystem) OR “ecosystem from review papers. The resultant behaviour of function” OR “ecosystem services” OR these relationships was then determined. “ecosystem interactions” OR “conservation Behaviours can either be reinforcing, whereby medicine” OR bushmeat OR (gender AND change in one direction is intensified by more ecosystem) OR anthroponoses OR change or balancing, in which change in one anthroponotic OR anthroponosis OR direction is countered with change in the opposite zooanthroponoses OR zooanthroponosis OR direction. zooanthroponotic) AND (“wildlife poisoning” OR “human health” OR “animal health” OR “wildlife A systems map was created in three “layers” using health” OR “one health” OR “global health” OR systems dynamic modelling software (Vensim, “planetary health” OR zoonoses OR zoonotic 2015). The primary domains of One Health (human OR zoonosis) AND (Africa’s OR Africa OR health, ecosystem health, agriculture, land use African OR Algeria OR Angola OR Benin OR change, and climate) constituted the first layer. The Botswana OR “Burkina Faso” OR Burundi OR finer scale components of these systems, as Cameroon OR “Cabo Verde” OR “Central identified from the literature review, constitute the African Republic” OR Chad OR Comoros OR second layer. The third layer of the system consists “Democratic Republic of Congo” OR “Cote of the direction of relationships between these components.