Background. Human noroviruses are among the most common enteropathogens globally, and are a leading cause of infant diarrhea in developing countries. However, data measuring the impact of norovirus at the community level are sparse.Methods. We followed a birth cohort of children to estimate norovirus infection and diarrhea incidence in a Peruvian community. Stool samples from diarrheal episodes and randomly selected non-diarrheal samples were tested by polymerase chain reaction for norovirus genogroup and genotype. Excretion duration and rotavirus coinfection were evaluated in a subset of episodes.Results. Two hundred twenty and 189 children were followed to 1 and 2 years of age, respectively. By one year, 80% [95% confidence interval (CI):75-85] experienced at least one norovirus infection and by 2 years, 71% [CI:65-77] had at least one episode of norovirus-associated diarrhea. Genogroup (G)II infections were three time more frequent than GI. Eighteen genotypes were found; GII genotype 4 accounted for 41%. Median excretion duration was 34.5 days for GII versus 8.5 days for GI infection (p=0.0006). Repeat infections by the same genogroup were common but repeat infections by the same genotype were rare. Mean length-for-age Z-score at 12 months was lower among children with prior norovirus infection compared to uninfected children (coefficient: -0.33, 95%CI: -0.65 to -0.01, p=0.04); the effect persisted at 24 months.Conclusions. Norovirus infection occurs early in life and children experience serial infections with multiple genotypes, suggesting genotype-specific immunity. An effective vaccine would have a substantial impact on morbidity, but may need to target multiple genotypes.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)