Emerging Infectious Disease

Livelihood Security & Freedom from Poverty

Food Security & Dietary Health

Emerging Infectious Disease

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Vaccination drive in Africa

Global environmental change has played a significant role in the emergence, resurgence or spread of several infectious diseases of humans, plants and animals. A failure by the global community to address the root causes of disease emergence associated with human impacts on wildlife and ecosystems could have severe global consequences.

Naturally occurring microbes - including bacteria, viruses, fungi and protozoa - comprise a significant portion of wild biodiversity worldwide. In many ways, these organisms are responsible for supporting and regulating a range of key ecosystem functions, and so provide the foundation for a wide range of ecosystem services. For example, bacteria and fungi are vital to waste decomposition and nutrient cycling, driving primary productivity and affecting climatic patterns on a massive scale. Disease-causing microbes (pathogens) and parasitic invertebrates play an equally important role in ecosystem functioning and productivity, and - though it is perhaps paradoxical and an unpleasant thought - are essential to maintaining the health of ecosystems and populations of wild flora and fauna. Cycles of infection, disease, morbidity and mortality have played an essential part in natural selection and the evolution of life, and have also driven the evolution of human societies and cultures.

The relationship between biodiversity loss and the emergence and spread of new and more virulent disease organisms is of growing international importance. There is clear scientific evidence that outbreaks of many diseases, including SARS, Ebola, hanta viruses, malaria, and the HIV pandemic, have resulted from human impacts on wildlife and ecosystems, including inter alia habitat disturbance, unsustainable trade in bushmeat and other country foods, and the wildlife trade. Urban sprawl, encroachment into wilderness areas, and pollution of oceans and inland waterways have also been linked with the spread of diseases of people and wildlife. Outbreaks of zoonoses (diseases spread from animals to man), including the recent international spread of the H5N1 strain of avian influenza, may also be facilitated by these activities as they affect the integrity of ecosystems and the services they provide. The loss of biodiversity and ecosystem services is increasingly recognised as a risk factor in the transmission of diseases between people, livestock, crops and wildlife.

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There are also some negative associations between high biodiversity and disease risk which must be recognised. Research has shown that, in certain specific areas or situations, disease risk may increase with proximity to wild areas or intact habitats, including for example certain forest areas or wetlands. Where this has been determined, the causes are not always clear and are rarely straightforward, and overall it is clear that the occurrence of high biodiversity is often less important as a risk factor than the integrity of the ecosystems involved, and the interactions which take place between people, wildlife and the environment. The influence of climate change on ecosystem processes and disease ecology is a further complicating factor, and it is increasingly clear that each situation must also be assessed at the landscape level, accounting for the role of people and ecosystems in the wider ecological landscape.

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Young birds on a goose farm
To address these complex issues, whether from the perspective of public health, food safety, wildlife conservation, economics, global security or international development, increased co-operation between disciplines is essential. A failure to address the root causes of disease emergence and spread associated with ecosystem change or impacts on wildlife could have severe global consequences. It is essential that the use of biodiversity indicators and the protection of ecosystems be integrated into international efforts to protect public health and prevent the emergence and spread of infectious diseases. At the same time, biodiversity conservation planning must account for the ecosystem services associated with the regulation of pests and diseases, and for how conservation plans may affect the health or livelihoods of local communities.



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