Norwalk-like gastroenteritis epidemic in a Toronto hospital.

An epidemic of gastroenteritis in a teaching hospital affected 57 patients and 69 staff over a 26-day period. The index case was a patient admitted with acute abdominal pain and diarrhea two days prior to the outbreak. The epidemic curve indicated person-to-person transmission. The incubation period, duration and types of symptoms were typical of Norwalk gastroenteritis, and Norwalk-like virus particles, serologically different from the prototype Norwalk virus strain, were observed in 17 of 20 fecal specimens examined by immune-electron microscopy.