Rotavirus genotypes in sewage treatment plants and in children hospitalized with acute diarrhea in Italy 2010 - 2011

Although the molecular surveillance network RotaNet-Italy provides useful nation-wide data on rotaviruses causing severe acute gastroenteritis in children in Italy, scarce information is available on rotavirus circulation in the general Italian population, including adults with mild or asymptomatic infection. This study investigated the genotypes of rotavirus present in urban wastewaters, and compared them with viral strains from clinical pediatric cases. During 2010 and 2011, 285 sewage samples from 4 Italian cities were tested by RT-PCRs specific for rotavirus VP7 and VP4 genes. Rotavirus was detected in 172 (60.4%) samples, 26 of which contained multiple rotavirus G (VP7 gene) genotypes, for a total of 198 G types. Thirty-two samples also contained multiple P (VP4 gene) genotypes, yielding 204 P types in 172 samples. Genotype G1 accounted for 65.6% of rotaviruses typed, followed by G2 (20.2%), G9 (7.6%), G4 (4.6%), G6 (1.0%), G3 (0.5%), and G26 (0.5%). VP4 genotype P[8] accounted for 75.0% of strains, P[4] for 23.0%, and the uncommon P[6], P[9], P[14], and P[19] for 2.0% of strains altogether. These rotavirus genotypes were also found in pediatric patients hospitalized in the same areas and years but in different proportions. Specifically, genotypes G2, G9, and P[4] were more prevalent in sewage samples than among patients, which suggests either a larger circulation of these latter strains through the general population not requiring medical care or their higher survival in wastewaters. A high nucleotide identity in the G1, G2, and G6 VP7 sequences was observed between strains from the environment and patients.