High prevalence of G12P[8] rotavirus strains in Rio Branco, Acre, Western Amazon, in the post-rotavirus vaccine introduction period

University of State of Pará. Center for Biological and Health Sciences. Belém, PA, Brazil.Federal University of Pará, Pará. Center for Tropical Medicine. Belém, PA, Brazil.Municipality Secretary of Health. Rio Branco, Acre, Brazil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.Ministério da Saúde. Secretaria de Vigilância em Saúde. Instituto Evandro Chagas. Belém, PA, Brasil.The present study aimed to provide a molecular characterization of circulating rotavirus (RVA) strains in Rio Branco, Acre, in the post-rotavirus vaccination period, particularly with regard to the emerging, increasingly prevalent G12P[8] genotype. A total of 488 fecal specimens from diarrheic and non-diarrheic children were obtained between January and December 2012. RVA detection was initially performed using enzyme-linked immunosorbent assay (ELISA) method, followed by reverse-transcription polymerase chain reaction (RT-PCR) using specific primers. RVA was detected in 18.3 per cent (44/241) of the children with acute diarrhea and in 1.2 per cent (3/247) of the non-diarrheic children (P  0.001), with overall RVA-positivity of 9.6 per cent (47/488). The most common genotype was G2P[4] with 43.2 per cent (19/44) of the diarrheic cases, followed by G12P[8] (27.3 per cent, 12/44), G3P[6] (18.2 per cent, 8/44), G3P[8] (4.5 per cent, 2/44), and G12P[6] (2.3 per cent, 1/44). G12 samples belonged to lineage III and were from children aged 4û52 months. All of these children had acute diarrhea associated with fever (83.3 per cent, 10/12) and vomiting (66.7 per cent, 8/12). Most of the cases occurred in August (58.3 per cent, 7/12), 75 per cent (9/12) of which having received the full vaccination scheme with RotarixÖ. For the first time G12 was reported at relative high prevalence in Brazil. Our findings warrant further monitoring studies on the molecular characterization of circulating RVA strains after rotavirus vaccine introduction in Brazil and elsewhere, since the occurrence of either unusual our emerging genotypes may pose a challenge to vaccination strategies