ASYMPTOMATIC ROTAVIRAL INFECTION: SPREAD AND EPIDEMIOLOGICAL IMPORTANCE

There were age and seasonal features of the spread of submanifest forms of rotaviral infection with the aim of the assessment of their importance in epidemiology. In 2011-2015 2608 residents of Rostov-on-Don at the age from of 2 weeks to 90 years were examined by ELISA methods for the isolation of group A rotaviruses. The widespread of asymptomatic rotaviral infection was established in the population. Rotavirus was detected in 63.3% of patients aged of 0-1 year, 24.7% -from 2 to 14 years, and 12.5% - 15-90 years. There was revealed an active circulation of rotaviruses in all seasons of the year. In June and July, the infestation of adults is not reduced, children from 1 year to 14 years - 17.5% seems to be higher than in periods of seasonal rises of the morbidity rate. The high level of asymptomatic infection in summer, may indicate to a decline in circulation of epidemic strains and the predominance of avirulent variants of rotavirus. The heterogeneity of the viral populations increases, which creates conditions for the formation of a large number of new reassortants and genetic variants of the pathogen. Thus, asymptomatic infections prevailing among the population both serve as a major reservoir of viral gene pool, the source of new variants of the virus and play a major role in the immune selection of epidemic strains. There was substantiated the assumption that the cause a winter-spring seasonality of infection is the advantage in the spread of virulent strains of rotavirus over avirulent ones, which is realized at low temperatures that increase pathogen survival. Early summer-autumn surges in the incidence rate in the South of Russia can cause a skid by millions of tourists of new genotypes of rotavirus to the territory with favorable social conditions for their active circulation.