Norovirus Outbreak after a School Trip among Girls' High School Students

ABSTRACT

Norovirus is one of the common causative agents of viral gastroenteritis in developed countries. A large outbreak of gastroenteritis occurred among girls' high school students in Cheongju city, Chungbuk province, who had attended a school trip to Cheju island from 19 to 21 May 2003. One hundred and ninety six students were consistent with case definition and attack rate was 54.9%. The epidemic curve was characteristic of a point-source outbreak. The frequency of diarrhea was 1 to 6 times (76.8%) and the duration of diarrhea was within two days (85.1%) in most cases. The most common symptom with diarrhea was abdominal pain followed by headache, tenesmus, febrile sense, chill and vomiting. The following bacterial organisms, Salmonella spp, Shigella spp, Vibrio spp, Staphylococcus aureus, and E coli O157 were examined in 196 stool specimens, but no suspicious organism was detected. In virological examinations, Norovirus was dectected in 3 out of 25 stool specimens from the sick students. Among the 22 stool specimens of the food handlers during the school trip, both bacterial and virological examinations were all negative. Among the 13 environmental specimens, the groundwater of the hotel, where the students had stayed during their school trip, was contaminated with general bacteria and E. Coli. However, we could not detect Norovirus in the groundwater of the hotel. We concluded that Norovirus might be a possible cause of this outbreak, and the water supply of the hotel might be a probable source of this outbreak.