Pathogens can come from wild species — as with SARS-CoV-2, which originated in bats — or from domestic animals, as with MERS, which came from camels. Intensified farming systems create significant risk, as evidenced by the recent avian influenza outbreak.¹² While researchers have devised global risk maps showing regions of the world where the risk is highest, in practice the high-risk areas are too large to be practicably managed, so it is vital that we create more finely grained maps.

Understanding the risk also requires a better understanding of the necessary conditions for inter-species pathogen transmission. For example, it is often hypothesised that the risk is greatest when humans push into a new area and thus come into first contact with species whose pathogens might evolve to use humans as hosts. However, often when humans move into a new area they degrade wildlife habitat, driving out or exterminating many animal species. This might reasonably be expected to reduce the risk of a disease crossing over. Understanding human-animal ecosystem interactions is thus likely to be key.

A vital part of this will involve data-sharing and integrated practice in human and animal health research and treatment. At the moment, human and animal researchers tend to work in parallel, with little contact across the divide. Given the threat of zoonotic disease, this situation is not conducive to the prevention of future outbreaks. More use also needs to be made of social and anthropological science, and local knowledge and insight, especially when resulting from “citizen science” projects, although progress is being made in these areas.¹³