Jpn. J. Infect. Dis., 52, 1999
Laboratory and Epidemiology Communications
Outbreak of Acute Gastroenteritis Caused by Human Group C Rotaviru in a Primary School
Masako Hamano*, Mitsutaka Kuzuya, Ritsushi Fujii, Hajime Ogura, Tadashige Mori, Toshitsuki Nakayama1, Eiji Yuen1, Ken-ichi Katayama, Yasunori Mitsunobu1 and Kohjiroh Inoue1
Department of Microbiology, Okayama Prefectural Institute for Environmental Science and Public Health, 739-1 Uchio, Okayama 701-0298 and 1Okayama Prefectural Maniwa Public Health Center, 620-5 Katsuyama, Katsuyama-cho, Maniwa-gun, Okayama 717-0013, Japan
In most cases, gastroenteritis caused by human group C rotavirus (CHRV) is sporadic. However, beginning with an outbreak in Fukui Prefecture in 1988 (1), several mass outbreaks of CHRV gastroenteritis have been reported in Japan (2-6). As shown in Table 1, outbreak at schools has been frequent in April and May. This report briefly summarizes a similar outbreak in a primary school in Okayama Prefecture (7).
On May 21 1999, a prefectural public health center received a report on an outbreak of gastroenteritis with diarrhea and vomiting in the first and second year classes of a primary school in the northwest part of Okayama Prefecture. The outbreak was investigated immediately. The patients were all children. Teachers or other employees of the school were not affected. The first patient appeared on May 15. The outbreak peaked on May 21, though new patients continued to appear until June 3 (Fig. 1).
Among 210 children in the school, 76 showed symptoms of gastroenteritis. The lower age group was the more affected: 55% (36/66) in 1-2 year classes (6-8 years of age), 27% (17/64) in 3-4 year classes (8-10 years of age) and 29% (23/80) in 5-6 year classes (10-12 years of age). Clinical symptoms exhibited by each group are summarized in Table 2. The lower age group tended to show severer symptoms, such as diarrhea and fever. The symptomatic period was variable from 1 to 10 days (average 3.1 days).
Stool specimens were obtained 3-12 days after the appearance of the symptoms from patients who became sick on May 15-24. We were unable to isolate any pathogenic enteric bacteria. Electronmicroscopy, however, detected rotavirus in 15 of 20 stool specimens (75%). An ELISA test (Rotaclone, TFB Co., Tokyo) revealed them to be negative for group A rotavirus (8), but the specimens were shown positive for group C rotavirus by a reverse passive hemagglutination test (RPHA kit for CHRV, Denka-Seiken Co., Tokyo) which we developed (9). The hemagglutination titer was high (=, >320) in 12 specimens. We were able to detect CHRV with this method as late as 12 days after the onset of illness.
As the outbreak peaked on 21 May, the lunch prepared in the school was suspected as a source of food poisoning. Seven meal specimens which were served on May 17-20 were tested for CHRV by RT-PCR (10). No CHRV was detected. The persons in charge of preparing the lunch were examined for the rotavirus infection but they were all negative. The route of the rotavirus infection remains unknown. Person-to-person infection could not be excluded.
REFERENCES
*Corresponding Author: E-mail:masako_hamano@pref.okayama.jp, Fax:+81-86-298-2088
Go to JJID Homepage Go to JJID 52(4)