Prevalence and phylogenetic analysis of rotavirus genotypes in Thailand between 2007 and 2009

Rotaviruses are the most common cause of severe diarrhea among infants and young children worldwide, especially in developing countries. In Thailand, rotavirus has presented a major public health problem causing severe diarrhea in infants and young children. It was responsible for about one-third of diarrheal diseases in hospitalized patients. In this study, we have analyzed the distribution and performed molecular characterization of rotaviruses circulating in infants and young children with diarrhea admitted to the city and rural hospitals in Thailand between July 2007 and May 2009. Group A human rotavirus was detected in 158 (28.4%) of 557 fecal specimens by RT-PCR. The peak incidence of infection was found in the winter months between December and March. The G1P[8] strain was identified as the most prevalent (49.4%) followed by G9P[8] (22.2%), G2P[4] (20.2%) and G3P[8] (0.6%). The uncommon strains G12P[8], G12P[6] and G3P[9] were also detected. Phylogenetic analysis of selected G and P genotypes isolated in this study was performed to compare with the reference strains from different countries. Emergence of G12 in the northern part of Thailand was observed and phylogenetic analysis demonstrated close relation between Thai isolates and strains from India. The present study reveals the recurring changing genotypes of rotavirus circulating in Thailand. The genetic association between isolates from Thailand and other countries ought to be considered with regard to local and global dissemination of rotavirus as it is crucial for prevention especially, with respect to vaccine implementation.