P-33. Contribution of noroviruses in causing acute gastroenteritis in Pune, Western India

Noroviruses are considered to be the major cause of non-bacterial acute gastroenteritis in both outbreak as well as sporadic cases. Present study was conducted to know the contribution of noroviruses in causing sporadic infections of acute gastroenteritis in Pune, western India. A total of 192 fecal specimens were collected during December 2005-June 2006 from children at 5 years of age hospitalized for acute gastroenteritis. All specimens were tested for the presence of norovirus GI and GII by RT-PCR using primers from RNA-dependent RNA polymerase (RdRp) gene. Sequencing data obtained from all PCR products was analyzed to know the prevalent genotype. Of the 192 fecal specimens, 24 (12.5%) were tested GII positive. Co-infection with rotavirus was detected in two of 24 specimens. Among the patients who suffered from norovirus infection, clinical severity score calculation showed that majority (70.8%) experienced severe disease while 29.2% cases presented with moderate disease. Highest number of norovirus infections was found in the month of March while lowest was in May. Phylogenetic analysis of nucleotide sequences of all 24 strains from Pune placed 15 strains in GII/4 cluster (62.5%), 3 strains in GII/2 cluster (12.5%), 1 strain in GII/3 cluster (4.1%), 1 strain in GII/1 cluster (4.1%) and 4 strains in new norovirus genetic cluster GIIb (16.6%). These findings revealed the possibility of norovirus as the second most common cause of non-bacterial acute gastroenteritis, after rotavirus, in western India with the predominance of GII/4 subgroup.