Changing pattern of prevalence, genetic diversity, and mixed infections of viruses associated with acute gastroenteritis in pediatric patients in New Delhi, India

There are very few studies that have assessed multiple viral agents causing Acute-Gastroenteritis (AGE) in India. The present study compared the changing pattern of prevalence and genetic diversity of five enteric viruses associated with acute-diarrhea in Delhi children within a gap of 5 years. Fecal samples were collected from diarrheal children (<4 years) during two winter seasons: year 2009-2010 (n=59) and year 2014-2015 (n=85). Samples were individually tested for rotavirus-A, norovirus, astrovirus, adenovirus, and sapovirus using EIA/RT-PCR and genetically characterized by phylogenetic analysis. Rotavirus was the most predominant (54.9%) virus followed by norovirus (25.7%), astrovirus (8.3%), and adenovirus (4.9%) with rare detection of sapovirus (0.7%). While detection rate increased for both rotavirus (49.2-58.8%) and astrovirus (5.1-10.6%), norovirus detection rate decreased (30.5-22.4%) from 2009 to 2015. During the same time period, adenovirus detection remained low (4.7-5.1%). Interestingly, mixed infections increased from 8.5% to 16.5% after 5 years. G1P[8] rotavirus strain was found most predominant (40%). Both type-1 and 8 astroviruses were detected. Single sapovirus detected was of genotype GII.1. Both GI (GI.5, GI.3) and GII (GII.1, GII.4, GII.7, GII.21, GII.13) genogroups of norovirus were detected. Of particular significance was the first detection of other NoV genotypes (besides GII.4 and GI.3) in Delhi. This is also the first report of NoV GI.5 from India. A change in prevalence pattern and increased diversity from 2009 to 2015 emphasizes the need for continued enteric virus surveillance to help measure the impact of new diarrhea vaccine(s) introduced in India.