Outbreak of acute gastroenteritis caused by human group C rotavirus in a youth educational center in Okayama Prefecture

In May 2000, an outbreak of acute gastroenteritis caused by human group C rotavirus (CHRV) occurred in a youth educational center located in the southern area of Okayama Prefecture. A total of 172 schoolchildren and teachers, who consisted of 51 persons belonging to F school and 121 persons belonging to K school, joined in an educational program at the center from May 24 to 26. Eighty-seven individuals (50.6%) of them showed clinical symptoms of gastroenteritis from May 24 to 30, and the outbreak peaked on May 27. The major clinical symptoms were abdominal pain (87.4%), diarrhea (50.6%), nausea or vomiting (21.8%), fever > 37 degrees C (12.6%), and headache (14.9%). The clinical symptoms of the patients in F school were more severe than those in K school. Thirty-two fecal specimens were collected from the patients and examined for gastroenteritis viruses by electron microscopy, ELISA, reverse passive hemagglutination test, and reverse transcription (RT)-PCR. As a result, CHRVs were detected in 21 specimens (65.6%) by RT-PCR. The possible route of the CHRV infection was thought to be a person to person transmission by following reasons: (i), CHRVs were detected in stools from patients who became ill on the first day of the program; (ii), CHRVs were not detected in stools from cooks; (iii), no possible causal food was found by epidemiological analysis of the outbreak. Furthermore, phylogenetic analysis of the VP7 gene among CHRVs isolated in Okayama revealed that the virus detected in this study was more closely related to the virus isolated from a sporadic case of gastroenteritis in 1996 than that isolated from an outbreak occurred in 1999.