Clinical and Virological Characteristics of Rotavirus Gastroenteritis and Prevalence of Strains in Tochigi, Japan

Aim: Rotavirus infection is a serious gastrointestinal infection that is usually prevalent during winter months and often seen in infants and young children. Studies on genotypes of prevalent rotavirus strains are important for preventing infection, developing vaccines, and its evaluation. The purpose of this study was to make an investigation of a rotavirus infection in the Nasu Region of Tochigi, Japan and to compare findings to those of other regions. Materials and Methods: We examined the clinical findings in 147 patients who attended the Department of Pediatrics at International University of Health and Welfare Hospital in the Nasu-shiobara City, Tochigi Prefecture, Japan during April 1, 2008 to March 31, 2010. Results: We analyzed the clinical findings of 37 patients with a fecal sample positive for rotavirus antigen. Furthermore, viral genotypes were determined using rotavirus-positive samples from 27 of these 37 patients. The genotypes were determined as G1P [8] in 5 samples, G3P [8] in 5 samples, G9P [8] in 3 samples, and G6P [9] in 2 samples. We were able to analyze the phylogenetic trees of these genotypes. Conclusion: Of particular note, we detected G6P [9] which were extremely rare in humans but common in cattle. Studies on changes in prevalent strains after vaccine introduction need to be conducted.