The coronavirus pandemic, suspected of originating in bats and pangolins, has brought the risk of viruses that jump from wildlife to humans into stark focus.
These leaps often happen at the edges of the world’s tropical forests, where deforestation is increasingly bringing people into contact with animals’ natural habitats. Yellow fever, malaria, Venezuelan equine encephalitis, Ebola – all of these pathogens have spilled over from one species to another at the margins of forests.
As doctors and biologists specializing in infectious diseases, we have studied these and other zoonoses as they spread in Africa, Asia and the Americas. We found that deforestation has been a common theme.
More than half of the world’s tropical deforestation is driven by four commodities: beef, soy, palm oil and wood products. They replace mature, biodiverse tropical forests with monocrop fields and pastures. As the forest is degraded piecemeal, animals still living in isolated fragments of natural vegetation struggle to exist. When human settlements encroach on these forests, human-wildlife contact can increase, and new opportunistic animals may also migrate in.
The resulting disease spread shows the interconnectedness of natural habitats, the animals that dwell within it, and humans.