28 in this study. The Guinea-Bissau cohort [14] reported a proportion of 0.40 and it was one in three infections for the Mexican cohort [13]. The measure of pathogenicity is very sensitive to the accuracy of detection of asymptomatic infections which usually have low viral excretion and thus the estimate of Guinea-Bissau where neither serology nor molecular techniques were used could possibly be overestimated. Though rotavirus infects children throughout the first three years of life, in some developing country settings it displays an affinity toward neonates.

In this study, 18% of the children were infected find more in the first month. This phenomenon has been reported earlier in various studies [19], [20], [21] and [22] and in hospitalized settings [23] and [24]. One explanation could be that a newborn, exposed to an environment saturated with the virus, is more likely to get infected or that neonates might be infected with specific strains that could bind to receptors not expressed in the post-neonatal period [25]. While rotavirus infections occurred throughout follow up, disease was seen mainly between the ages of 4–12 months. During early infancy, the child seemed to be protected from developing diarrhea due

to rotavirus, as evident from the proportionately higher asymptomatic infections in the first three months. Beyond three months, rotavirus produced symptoms more often. As the child crossed the age Parvulin of one year, the proportion selleck chemical of rotavirus infections developing into disease decreased and stayed low until the end of the follow-up. This was also demonstrated by Velazquez et al. [26] where rotavirus associated diarrhea was found to peak between 4 and 6 months and asymptomatic infections were more frequent in the first three months and beyond 10 months. Description of the natural history of rotavirus, especially of asymptomatic infections is limited. The Kaplan Meier estimates from the Mexican cohort [13] showed that 34% of the children were infected

by six months, 67% by one year and 96% by the age of two years. The West African cohort found that 26% infected by six months, 46% by one year and 74% by the age of two years [14]. While the survival curves of these two cohorts were gradual and uniform, the Vellore cohort displayed a steeper curve initially with a high incidence rate and 43% infected by six months. The late infancy window of a high rate of symptomatic rotavirus infection has been reported previously in many studies [27], [28] and [29]. This may occur following the waning of the maternal antibodies known to be protective against disease and preceding the steady build-up of child’s immune system, or corresponding to weaning, and increased levels of contamination.