Nipah virus is a lethal zoonotic disease that passes from bats to humans in what are called "spillover events." But it’s still not known for sure how outbreaks happen, which makes prevention difficult. Epidemiologist Emily Gurley, who has studied Nipah outbreaks in Bangladesh for nearly 20 years, talks with Lindsay Smith Rogers about her work tracking the virus’s transmission and the enormous amount of multi-disciplinary resources and complexity required to investigate spillover events.