[Food-borne outbreaks of gastroenteritis caused by small round structured viruses. 1. Four outbreaks of gastroenteritis associated with oyster consumption].

Between December 9, 1988 and January 28, 1989, there were four outbreaks of acute gastroenteritis in Saitama prefecture. Eighty-two of 123 persons (67%) attending four banquets in restaurants became ill: 44 cases attending three banquets were related to eating raw oysters, and 38 attending one banquet to eating sashimi. The most common symptoms were nausea, diarrhea, abdominal cramps, and vomiting. Average incubation periods were 29 to 32 hours long. Bacteriologic analysis of stool specimens did not reveal causative agents. Small round structured viruses were detected in fecal specimens from 19 of 39 ill persons (49%) by electron microscopy. In one of four outbreaks, the formation of antibody to small round structured virus in paired serum samples was detected by western blot test. Small round structured viruses were implicated as the etiologic agents in four outbreaks of acute gastroenteritis.