Rapid changes in rotaviral genotypes in Ecuador.

Previous studies suggest that the emerging G9P[8] genotype was the most prevalent rotavirus genotype in Ecuador during 2005. This present study provides a temporal analysis of the distribution of rotavirus genotypes in two locations within Ecuador by adding additional years (2006 - early 2008) to the originally reported 2005 data. Data were collected in a rural (northern coastal Ecuador) and urban (Quito) area. In the rural area, a community sample of cases (those presenting diarrhea) and controls (those not presenting diarrhea) were collected between August 2003 and March 2008 resulting in a total of 3,300 stool samples (876 cases and 2,424 controls). Of these samples, 260 were positive for rotavirus by an immunochromatographic test (196 cases and 64 controls). In Quito, 59 fecal samples were collected from children presenting diarrhea and diagnosed with rotavirus. An RT-PCR analysis of samples collected between 2005 and 2007 suggested that G9 was replaced by G1 and G2 in the rural and urban settings. During this period G9 decreased from 79% to 9% while G2 increased from 0% to 43% in the rural communities, and G9 decreased from 79% to 37% while G2 increased from 3% to 57% in the urban area of Quito. This rapid replacement of G9 by G1 and G2 reinforces the necessity of surveillance to inform vaccination programs.