Patterns of zoonotic disease risk in Africa as linked to biodiversity measures and human impact

Background Zoonotic diseases threaten public health worldwide; for instance, >11,000 people may have died during the 2013-2016 Ebola outbreak in western Africa. There seems to be a link between biodiversity and disease prevalence and distribution, though the mechanisms via which biodiversity impacts in disease outbreaks are not well understood. The spread of pathogens between humans and animals (wild and domestic) has been facilitated by increasing human activity. In the twenty-first century, as our impacts grow even further, it is therefore imperative to better understand the relationship(s) between biodiversity and zoonotic disease. Objective To determine the relationship(s) between biodiversity measures and outbreaks of seven viral zoonoses in Africa. Method Locations of zoonotic disease outbreaks were compiled from primary literature and the World Health Organisation (WHO). Maximum Entropy modelling software (MaxENT) was used to create niche models for each disease using different combinations of abiotic and biotic variables, to explore the impact of each. Results Areas where human impacts were most substantial had much increased risks of zoonotic disease outbreak, for every disease we modelled. Different diseases had different relationships with the biodiversity of particular animal groups (including primates). In some cases, higher biodiversity seemed to increase outbreak risk and in others the opposite. Conclusion Relationships between zoonotic disease outbreaks and biodiversity are complex, but niche models for specific diseases can help. Conserving and managing biodiversity in a disease-sensitive way is likely to be key to reducing risk in the twenty-first century.