An outbreak of group A rotavirus G1P[8] in an elementary school, Nara prefecture.

*Corresponding author: Mailing address: Virology and Bacteriology Division, Nara Prefectural Institute for Hygiene and Environment, Ohmori-cho, Nara City, Nara 630-8131, Japan. Tel: +81-742-20-2887, Fax: +81-742-27-0634, E-mail: y.inoue @ihe.pref.nara.jp Rotavirus is the most common cause of severe diarrhea among children. There are seven groups of this virus (A to G), and A, B and C rotaviruses infect humans. Generally, group A rotavirus infection is predominant in babies of 0 to 2 years old, while it is much less common in children older than 5 years. In the present report, we describe a group A rotavirus outbreak case that occurred in an elementary school in late April 2008, in Nara Prefecture. A public elementary school in the central area of Nara Prefecture reported to Katsuragi Health Center about a possible outbreak of epidemic gastroenteritis on April 25, 2008. Many in the school pupils were absent because of diarrhea with vomiting and fever. Immediately, the health center gave the school guidance on outbreak prevention and began an investigation. Eventually, 21 children, 12 boys and 9 girls aged 6 to 9 years old, developed the illness between April 24 and 28. Fourteen patients were second graders (7 to 8 years old) (Table 1). The health center collected stool specimens from 7 pupils (6 to 8 years old), and the specimens were tested at the Nara Prefectural Institute for Hygiene and Environment on April 26 for major gastroenteritis viruses: norovirus, adenovirus 40/41 and group A rotavirus. Four out of 7 specimens were found to be positive for rotavirus by latex agglutination assay (Rota-Adeno dry; Sekisui Medical Co., Ltd., Tokyo, Japan), while they were all found to be negative for other viruses. Genetic analysis was then conducted to detect the genes of G-antigen (VP7) and P-antigen (VP4) using the reverse transcription (RT)-polymerase chain reaction (PCR) method and type-specific primers (1,2). The extraction of genomic RNA was performed using the Quick Gene SP kit RNA Tissue (Fujifilm, Tokyo, Japan). RT and PCR were conducted with Rever Tra Ace and r-Taq DNA Polymerase (Toyobo, Osaka, Japan), respectively. Finally, the institute confirmed that the virus was a rotavirus of G1P[8], one of the major serotypes of group A rotavirus. To our knowledge, group A rotavirus-related outbreak cases are not unusual in child-care centers or kindergartens, but such cases are rather rare in elementary schools. Table 2 shows the number of rotavirus-related cases reported between 2005 Table 1. Number of patients per day in the elementary school