Rotavirus gastroenteritis and weather.

During 5.5 years of a study in Washington, D.C., hospitalizations of children for rotavirus gastroenteritis tended to be more common after a month of cold or dry weather than after a corresponding calendar month of warm or wet weather. Overall, there were 84% more (178 versus 97) inpatients with rotavirus gastroenteritis after a set of relatively colder individual months taken as a group than after an equal number of warmer corresponding calendar months taken as a group. Comparable differences were not seen with nonrotavirus gastroenteritis patients. There also were 45% more rotavirus hospitalizations after the set of months with the least depth of precipitation compared with the set of corresponding calendar months with the greatest depth of precipitation. Rotavirus infection in young infants, the children least likely to be directly exposed to outdoor conditions, showed some of the most marked weather-associated effects. These findings suggest that weather-related low indoor relative humidity and indoor crowding may be key factors in the epidemiology of rotavirus disease.