G2P[4] the most prevalent rotavirus genotype in 2007 winter season in an European non-vaccinated population

BACKGROUND: Recently, a high prevalence of G2P[4] rotavirus (RV) infection was reported from Brazil, and linked with the universal RV vaccination programme that used the G1P[8] live oral RV vaccine. OBJECTIVE: To determine the genotypes of RV co-circulating in a non-vaccinated population, in northern Portugal in the winter season of 2007. STUDY DESIGN: Prospective multicenter study of the genotypes circulating in the northwest region of Portugal during January to March 2007. Children with acute gastroenteritis, who attended the Pediatric Emergency Services of five Hospitals, were included in the study. The parents of the children completed a clinical and epidemiological data questionnaire and stool samples were collected. Stool samples positive in a RV enzyme immunoassay (EIA) were genotyped by reverse transcriptase-polymerase chain reaction. RESULTS: Stool samples were collected from 424 children. Two hundred and thirty-four (55.2%) stool samples were RV-positive. G2P[4] was the predominant RV type (68.6%), followed by G9P[8] (14.0%). CONCLUSIONS: Because our population was naïve for RV vaccine, the G2P[4] predominance cannot be explained by vaccination. Rather, this high prevalence of G2P[4] may be within the normal fluctuation of RV genotypes. RV strain surveillance programmes are important for informing RV vaccination programmes.