Norovirus Gastroenteritis in a Birth Cohort in Southern India.

BACKGROUND: Noroviruses are an important cause of gastroenteritis but little is known about disease and re-infection rates in community settings in Asia. METHODS: Disease, re-infection rates, strain prevalence and genetic susceptibility to noroviruses were investigated in a birth cohort of 373 Indian children followed up for three years. Stool samples from 1856 diarrheal episodes and 147 vomiting only episodes were screened for norovirus by RT-PCR. Norovirus positivity was correlated with clinical data, secretor status and ABO blood group. RESULTS: Of 1856 diarrheal episodes, 207 (11.2%) were associated with norovirus, of which 49(2.6%) were norovirus GI, 150(8.1%) norovirus GII, and 8 (0.4%) were mixed infections with both norovirus GI and GII. Of the 147 vomiting only episodes, 30 (20.4%) were positive for norovirus in stool, of which 7 (4.8%) were norovirus GI and 23 (15.6%) GII. At least a third of the children developed norovirus associated diarrhea, with the first episode at a median age of 5 and 8 months for norovirus GI and GII, respectively. Norovirus GI.3 and GII.4 were the predominant genotypes (40.3% and 53.0%) with strain diversity and change in the predominant sub-cluster over time observed among GII viruses. A second episode of norovirus gastroenteritis was documented in 44/174 (25.3%) ever-infected children. Children with the G428A homozygous mutation for inactivation of the FUT2 enzyme (se428se428) were at a significantly lower risk (48/190) of infection with norovirus (p = 0.01). CONCLUSIONS: This is the first report of norovirus documenting disease, re-infection and genetic susceptibility in an Asian birth cohort. The high incidence and apparent lack of genogroupII specific immunity indicate the need for careful studies on further characterization of strains, asymptomatic infection and shedding and immune response to further our understanding of norovirus infection and disease.

Exposure to human and bovine noroviruses in a birth cohort in southern India from 2002 to 2006.

Human and bovine norovirus virus-like particles were used to evaluate antibodies in Indian children at ages 6 and 36 months and their mothers. Antibodies to genogroup II viruses were acquired early and were more prevalent than antibodies to genogroup I. Low levels of IgG antibodies against bovine noroviruses indicate possible zoonotic transmission.

Rotavirus antigenemia in Indian children with rotavirus gastroenteritis and asymptomatic infections.

BACKGROUND: Rotavirus gastroenteritis results in significant morbidity and mortality in Indian children. Although there are numerous studies on rotavirus diarrhea, there are few reports on antigenemia and extraintestinal presentations in these populations. METHODS: Following screening for rotavirus antigen of stool samples from children with and without acute gastroenteritis with a commercial enzyme immunoassay (EIA), a total of 199 stool and serum sample pairs were identified for additional testing. All EIA-positive stool samples were genotyped, and viral load estimated by real-time reverse-transcriptase polymerase chain reaction (RT-PCR). Serum samples were tested for rotavirus antigen by an in-house EIA, and antigen was quantified by optical density. Scoring of disease severity was performed for all hospitalized children. Data on extra-intestinal presentations were collected if available. RESULTS: Based on screening of stool samples by EIA, the study population could be divided into 3 groups, including 111 children with rotavirus diarrhea, 44 children with diarrhea and no rotavirus detected in stool specimens, and 44 children with asymptomatic rotavirus infection. Antigenemia was significantly higher among children with rotavirus diarrhea (50.4%) than among children with non-rotaviral diarrhea (16%) or asymptomatic infections (2.3%) (P < .001). Low copies of rotavirus were detected by RT-PCR in all 7 children with EIA-negative stool specimens and antigenemia. Presence and levels of rotavirus antigen in serum specimens correlated with stool viral load. Children with antigenemia had significantly more-severe disease but not more extraintestinal presentations than did children without antigenemia. CONCLUSIONS: Antigenemia occurs frequently in rotavirus infection and correlates with virus replication in the gut but not with extra-intestinal presentations.