BACKGROUND: Noroviruses (NoV) are important causes of acute gastroenteritis in infants and young children. This study investigated the prevalence of NoV infections in infants and children with acute gastroenteritis in Japan from July 2006 to June 2007. METHODS: A total of 628 fecal specimens were collected from infants and children with acute gastroenteritis in five different places (Maizuru, Tokyo, Sapporo, Saga and Osaka), Japan during the period of July 2006 to June 2007. All fecal specimens were examined for NoV by reverse transcription-polymerase chain reaction. Molecular analysis of NoV was carried out by sequencing methods. RESULTS: From 628 fecal specimens tested, 15.6% (99 of 628) were positive for NoV. Of these, NoV GII most predominant, with a prevalence of 15.5% (97 of 99). Analysis of nucleotide and amino acid sequences revealed that NoVGII strains comprised GII/4 (89%), GII/3 (6.4%), GII/7 (2.3%), and GII/2 (2.3%) genotypes. Among NoVGII/4 strains, all of them belonged to genotype GII/4 2006b variants. Our results clearly indicated that NoV infections were most commonly observed in winter seasons in Japan. CONCLUSIONS: In conclusion, this study shows the predominance of NoVGII/4 2006b variants and NoV is still burden of disease among Japanese pediatric population.
BACKGROUND: Noroviruses (NoV) are important causes of acute gastroenteritis in infants and young children. This study investigated the prevalence of NoV infections in infants and children with acute gastroenteritis in Japan from July 2006 to June 2007. METHODS: A total of 628 fecal specimens were collected from infants and children with acute gastroenteritis in five different places (Maizuru, Tokyo, Sapporo, Saga and Osaka), Japan during the period of July 2006 to June 2007. All fecal specimens were examined for NoV by reverse transcription-polymerase chain reaction. Molecular analysis of NoV was carried out by sequencing methods. RESULTS: From 628 fecal specimens tested, 15.6% (99 of 628) were positive for NoV. Of these, NoV GII most predominant, with a prevalence of 15.5% (97 of 99). Analysis of nucleotide and amino acid sequences revealed that NoVGII strains comprised GII/4 (89%), GII/3 (6.4%), GII/7 (2.3%), and GII/2 (2.3%) genotypes. Among NoVGII/4 strains, all of them belonged to genotype GII/4 2006b variants. Our results clearly indicated that NoV infections were most commonly observed in winter seasons in Japan. CONCLUSIONS: In conclusion, this study shows the predominance of NoVGII/4 2006b variants and NoV is still burden of disease among Japanese pediatric population.