Infectious diseases threaten human health and food production. The richness of wild animal species in an area is an important determinant of disease risks, because host species vary in their competences for pathogen transmission. A decline in biodiversity may either increase or decrease disease risks. It is, thus, important to know where and when changes in disease risks might be expected. Wageningen University & Research studies how disease risks respond to global biodiversity changes and generates predictions on disease prevalence in animal populations that vary in species composition.