Deforestation and other forms of land conversion are driving exotic species out of their evolutionary niches and into manmade environments, where they interact and breed new strains of disease. As natural habitats shrink, wild animals concentrate in ever smaller territories or migrate to anthropogenic areas, such as homes, sheds and barns.

One of the authors of the study, Roger Frutos, a specialist in infectious diseases at the University of Montpellier, said multiple studies have confirmed that the density and variety of bat-borne viruses is higher near human habitation. Habitat destruction is an essential condition for the proliferation of a new virus, he added, but it is only one of several factors.