Spillover, the transfer of viruses from wild animals to humans, is a by-product of hunting, wild-animal trade, and proximity of humans to wild creatures. Dr. Jonathan Runstadler explains how spillover can cause pandemics in the modern global community, and why control of these viruses requires an understanding of the relationship between humans and these animal disease reservoirs. Image: Belmont Media Center

**Jonathan Runstadler** is a Professor of Virology, Immunogenetics, Disease Ecology, Cummings School of Veterinary Medicine at Tufts University.