Norovirus genotype IIb associated acute gastroenteritis in India

BackgroundIn India the role of noroviruses in causing gastroenteritis is not well defined.ObjectiveTo determine the norovirus prevalence in sporadic cases of acute gastroenteritis in western India.Study designA total of 236 fecal specimens consisting 192 specimens from hospitalized and 44 from OPD (outpatient department) children ≤5 years of age were tested for the presence of norovirus genogroup (G)I and GII by RT-PCR followed by sequencing. Multiple alignment and phylogenetic analysis were carried out to determine the norovirus genetic types.ResultsNorovirus GII infection was detected in 11.9% (28/236) specimens. These included 24 of 192 (12.5%) specimens from hospitalized and 4 of 44 (9.0%) specimens from OPD cases. Nucleotide sequence based analysis of norovirus GII strains indicated circulation of GIIb strains at a significant level in hospitalized (12.5%) and OPD (75%) children.ConclusionThis study demonstrates the predominance of GII/4 (genogroup II/genotype 4) along with co-circulation of GII/1, GII/2, GII/3 and GIIb revealing the possibility of norovirus as the second most common cause of non-bacterial acute gastroenteritis after rotavirus in western India. It also documents for the first time occurrence of norovirus GIIb infections in India.