Prevalence of antibodies to bovine herpes mammillitis virus in cattle of Rio Grande do Sul, Brazil

Bovine herpesvirus type 2 (BoHV-2), the agent of bovine herpetic mammillitis (BHM), has a worldwide distribution and was identified in Brazil in the 70's. Thereafter, cases of bovine mammillitis clinically compatible with BHM have been frequently reported by cattle owners and veterinarians, mainly in dairy herds, suggesting the dissemination of BoHV-2 among Brazilian cattle. This article reports a serologic survey for BoHV-2 antibodies in cattle from Rio Grande do Sul (RS), using serum samples obtained upon a statistically planned sampling as a part of the Program of Control/Eradication of Brucellosis and Tuberculosis (PNCBT). A total of 2.213 serum samples from cows with 24 months or older, predominantly from dairy herds, from 136 counties located in seven geographical regions of RS were tested by virus neutralization (VN). Serum samples with VN titers > 2 were detected in 24.5% (543/2.213) of the animals. Prevalence rates varied from 12.9% (22/170) in Porto Alegre metropolitan area to 48,9% (69/137) in the central-eastern region. In most regions, the highest prevalence rates were observed in dairy herds (32.3%), followed by double proposit (22%) and beef herds (17.6%). These results demonstrate that BoHV-2 infection is widespread among cattle in RS, and potentially involved in cases of mammillitis described in dairy cows.