The illness was mysterious. A 25-year-old graduate student had been hospitalized with a high fever, muscle and joint pain, a stiff neck, fatigue, sores in her throat, and a metallic taste in her mouth. She soon developed an angry rash. To make the diagnosis, her doctors had an important data point to consider: Days earlier, the woman had returned to the United States from a field expedition in South Sudan and Uganda, where she had been capturing and collecting the blood and tissue of bats and rodents. That information proved critical — and is newly relevant given concerns that the pandemic may have come from a research accident. Three days after she was admitted to the hospital in 2012, tests determined that the student was infected with a novel virus that infects a type of fruit bat that lives in the rural areas of Uganda.