Disease ecologist Tony Goldberg was stunned in 2016 when he learned that a mysterious infection was swiftly killing chimpanzees at a lush sanctuary in Sierra Leone’s rainforest. “It was not subtle—the chimpanzees would stagger and stumble, vomit, and have diarrhea,” recalls Goldberg of the University of Wisconsin, Madison. “Sometimes they’d go to bed healthy and be dead in the morning.”