Epidemiological aspects of porcine rotavirus infection in Venezuela

The prevalence of porcine rotavirus infection in Venezuela was studied from November 1980 to November 1981. Rotaviruses were identified in 21.3 per cent of 286 diarrhoeic samples analysed by electron microscopy and in none of the 48 controls. Rotaviruses were readily detected throughout the year, which may correspond to the absence of seasonal climatic variations in a tropical country such as Venezuela. Rotavirus infection was frequently observed in pigs that were two to six weeks old and was rare in younger animals. The age distribution of rotavirus infection correlated well with the presence of circulating antibodies, as measured by the complement fixation test. Sucking pigs less than two weeks old appeared to be protected from the infection by passive immunity; no antibodies were detected in the two- to three-week-old group, coinciding with an increased susceptibility to rotavirus infection. The antigenic specificity of the rotavirus isolates was confirmed by enzyme-linked immunosorbent assay test, using antibodies directed against the group-specific antigen of human rotavirus. Polyacrylamide gel electrophoresis of viral double-stranded RNA revealed an heterogeneity on the electropherotype of selected samples obtained at different times during the study period.