MOLECULAR EPIDEMIOLOGY STUDY OF ROTAVIRUS GROUP A CIRCULATION IN CHILDREN WITH AGE IN LOMBARDY (2008-2011)

Objectives: Our diagnostic virology laboratory, of the University of Milan, is part of RotaNet-Italy Study Group, a component of the EuroRotaNet. We assess co-circulation of different rotavirus-strain and new emerging strains in children with rotavirus infection. Our laboratory collets stool samples coming from different sentinel regional hospitals (Cremona, Legnano, Lecco and Melegnano) of the Lombardy region, Italy. Methods: During 2008-2011 we gathered the stool samples of 478 children (age: ≤5 years) that were proved positive for rotavirus group A by commercial rapid test. The molecular characterization of rotavirus strains, according with EuroRotaNet method and algorithm, was performed by ISS (Istituto Superiore di Sanità-Rome), that coordinates Italian rotavirus surveillance project. Results: Seven G/P combinations (G1P[8], G9P[8], G4P[8], G2P[4], G3P[8] and G10P[8], G2P[8]) were identified totally. In all 4 years 90% of samples were “common” genotypes while about 0.6 % were the “uncommon” types. The most frequent combination was G1P[8] (50%, range: 35-63%); the other “common” genotypes observed were: G9P[8] (19%, range: 9-30%), G4P[8] (12%, range: 9-17%), G3P[8] (4%, range: 2-6%) and G2P[4] (5%, range: 3-6%), in agreement with data from other Italian regions and European countries. “Uncommon” associations were detected in only 2008-2009 seasons: G10P[8] (0.4%, range: 0-1%) and G2P[8] (0.2%, range: 0-0.6%). Mixed infections were frequent, being identified in average 8.4% of cases (range: 6-10%) over the years. About 0.6% of all samples were negative and were detected only in the 2008-2009 season and 0.4% of all stool samples were non-typeable. Conclusion: The present study has shown that different rotavirus strains have been circulating among children with acute gastroenteritis (AGE) coming from sentinel hospitals distributed in various parts of Lombardy from 2008 to 2011. During replication rotavirus could change and interspecies transmission of rotavirus between animals and human are thought to happen frequently: since new strains could have antigenic and virulence characteristics that could cause more severe diseases, it is important to investigate the nature of these associations. Therefore it is necessary to carry on and improve the RotaNet programs of circulating strains monitoring both for epidemiological surveillance and vaccine implementation.