Worldwide, Brazil is the largest beef exporter and the sixth largest milk producer. The country has approximately 2.6 million farms and 170 million bovines. Dairy production is essentially directed to the domestic market. The activity has economic and social importance; 1.34 million farms produce 21 billion milk L/year (IBGE, 2006). Prevalence at animal and herd level ranging from 22% to 70% and 58–90% has been estimated in Brazil respectively (Canal et al., 1998, Poletto et al., 2004, Thompson et al., 2006, Quincozes et al., 2007, Frandoloso et al., 2008, Brito et al., 2010). These results suggest that BVDV exposure is as widespread in Brazil as it is in other endemic regions elsewhere, but observational studies that estimate the prevalence and associated risk factors for BVDV in the country are still lacking. In Uruguay and Argentina, bordering countries with the south of Brazil, herd prevalence of 100% and 93.1% has been found respectively (Guarino et al., 2008, Carbonero et al., 2011).
The objectives of this study were to identify factors that influence the probability that herds are seropositive for antibodies directed towards BVDV and to estimate the herd-level prevalence of BVDV infection using an indirect ELISA in a well-defined population in the State of Rio Grande do Sul, southern Brazil.