Close A bacterium has been killing chimpanzees in Sierra Leone. Scientists are worried that the said bacterium could eventually spread to humans. (Photo : Dominik Scythe on Unsplash) Researchers led by a team at the University of Wisconsin, Madison, published a study on Wednesday, announcing their findings in the journal "Nature Communications." The study showed that fifty-six (56) chimpanzees died from a similarly mysterious illness at the Tacugama Chimpanzee sanctuary and wildlife reserve. They covered the deaths between 2005 and 2018. The disease causes both gastrointestinal and neurological symptoms that are "not subtle," lead researcher Tony Goldberg said. "The chimpanzees would stagger and stumble, vomit, and have diarrhea," he said. "Sometimes they'd go to bed healthy and be dead in the morning."