Changing distribution of human rotavirus serotypes during two epidemic outbreaks of gastroenteritis in Campinas, São Paulo, Brazil, 2003-2004: Detection of G6 strains

Abstract Background Rotavirus serotypes G1–G4 and G9 are the most important agents of severe diarrhea in children worldwide. Objective To characterize rotavirus serotypes/genotypes causing two large outbreaks of diarrhea in Campinas, Sao Paulo, during 2003–2004. Study Rotavirus infection was investigated in 328 stool specimens collected from children and adults with diarrhea by PAGE and RT-PCR and further characterized by semi-nested PCR-typing assays. Results G3P[8] (26.1%), G9P[8] (18.7%) and G1P[8] (17.9%) were the most frequently detected serotypes/genotypes. G1P[8] was predominant in 2003, but significantly decreased the following year when G3P[8] and G9P[8] prevailed. G5P[8] was identified in about 9% of the typed specimens from each year consistent with its endemic nature in Brazil for over two decades. The other globally common serotypes (G4P[8] and G2P[4]), uncommon G-P combinations, and multiple G serotypes were also found. Rarely found in humans, and not previously reported in Brazil, serotype G6 was identified in three specimens obtained from children in 2004. Conclusion Multiple rotavirus serotypes were observed co-circulating in the city with serotype predominance changing between the two-year study. This study provides pre-vaccine baseline information on locally endemic strains that might help analysis of post-vaccine data.