Distribution of rotavirus genotypes after vaccine introduction in the Triângulo Mineiro region of Brazil: 4-Year follow-up study

Abstract

Background: Rotaviruses are the major cause of diarrhea in children for which a monovalent G1P[8] vaccine has been provided free for all Brazilian infants since March 2006.

Objectives: To investigate prevalence and genotypes of rotavirus strains causing diarrhea in children in Triângulo Mineiro, Minas Gerais, during 2007-2010, and to assess local vaccine impact.

Study design: Fecal specimens were analyzed for rotavirus detection and characterization by PAGE, RT-PCR and PCR-genotyping assays.

Results: Overall, rotavirus was diagnosed in 12.1% (76/630) cases, accounting for 35.8% of the hospitalizations and 6.5% of outpatient attendance due to diarrhea. A trend in rotavirus disease reduction occurred in both cities (71.8% and 83.4% in Uberaba; 95.3% in Uberlândia) up to 2009, but it reversed in 2010 with increased rotavirus cases in Uberlândia. Short pattern G2P[4] strains were detected in all but three (96%) cases of mixed/P[NT] infections with long electropherotypes.

Conclusions: This 4-year follow-up study showed a reduction in rotavirus-related diarrhea and even skipped a rotavirus season, which is consistent with vaccine mediated protection. The 2007-2010 rotavirus epidemic curve reflected the natural cyclic fluctuation of the single G2P[4] genotype, with sharp reduction of cases in 2008 leading to lack of a rotavirus 2009 season (both cases and hospitalizations) followed by its come back in 2010. Diarrhea cases related to either vaccine serotype/genotype (G1 or P[8]) were not detected. Thus, a new scenario emerged with a single epidemic genotype replacing the cocirculation of great diversity of genotypes, thus far, a hallmark of the epidemiology of rotavirus in Brazil.