The prevalence of enteric RNA viruses in stools from diarrheic and non-diarrheic people in southwestern Alberta, Canada.

Abstract

Southwestern Alberta is a region of Canada that has high rates of enteritis as well as high densities of livestock. The presence of enteric RNA viruses, specifically norovirus (NoV) GI, GII, GIII, GIV; sapovirus (SaV); rotavirus (RV); and astrovirus (AstV), was evaluated in stools from diarrheic (n=2281) and non-diarrheic (n=173) people over a 1-year period in 2008 and 2009. Diarrheic individuals lived in rural (46.6%) and urban (53.4%) settings and ranged in age from less than 1 month to 102 years, and the highest prevalence of infection in these individuals was in November. In all, viruses were detected in diarrheic stools from 388 individuals (17.0%). NoV GII was the most frequently detected virus (8.0%; n=182) followed by SaV (4.3%; n=97), RV (2.0%; n=46), AstV (1.8%; n=42), NoV GI (0.9%; n=20), and NoV GIV (0.1%; n=1). Animal NoV GIII was never detected. The prevalence of mixed viral infections in diarrheic individuals was 2.8% (n=11). Children from 1 to 5years of age accounted for the highest prevalence of positive stools, followed by the elderly individuals (≥70years). Only NoV GII (1.2%; n=2) and SaV (1.2%; n=2) were detected in stools from non-diarrheic people. Sequence analysis of a subset of stools revealed homology to NoV, SaV and RV sequences from humans but not to strains from non-human animals. The results of this study do not support the hypothesis that viruses of animal origin have a significant impact on the occurrence of acute gastroenteritis caused by RNA enteric viruses in people living in southwestern Alberta.