Prevalência e variáveis associadas à infecção por BoHV-1, BVDV, Leptospira spp. e Neospora caninum em bovinos leiteiros no município de Novo Xingu-RS

Abstract

Infectious reproductive diseases cause great economic losses to livestock production due to the occurrence of abortions, embryonic losses and production decrease. Thus, establishing an estimate of the distribution of these diseases in the herd is fundamental in the adoption of prevention and control measures. This study aimed to investigate the seroprevalence of antibodies against BoHV-1, BVDV, Leptospira spp. and Neospora caninum in the dairy herd of the municipality of Novo Xingu, determined by seroneutralization, microscopic agglutination test, immunofluorescence and ELISA, respectively. A total of 405 serum samples of dairy cattle from 109 herds were collected and the variables associated with infection by each agent were determined. Samples were divided into two categories according to the herd's vaccine status. Among the 147 vaccinated animals, 74.8% had antibody titers against BoHV-1, 53% against BVDV and 52.3% against Leptospira spp. Vaccination did not confer protective immunity in more than 40% of bovines. Among the 258 unvaccinated animals, 9.3% were positive for BoHV-1, 11.2% for BVDV, 12% for Leptospira spp. and 37.3% for N. caninum. The results showed that the municipality of Novo Xingu presented low prevalence of infection by BoHV-1, BVDV and Leptospira spp., with values up to 80% lower than the average of the southern region of the country. In contrast, there was a marked occurrence of Neospora caninum infection, 57% higher than the same average. The following variables were associated with the seropositivity of the animals: history of abortion, history of return to estrus, use of a maternity picket, mothers or grandparents with a history of abortion and presence of wild animals. There was also a correlation between history of abortion and mothers or grandparents with a history of abortion, probably due to vertical transmission between the animals. The low titers of antibodies conferred by commercial vaccines suggest that it necessary controlled studies about their quality and efficacy. The results of the serological tests were made available to the farmers, who received training on the particularities of the diseases, treatment possibilities, vaccination, destination of fetal membranes and other measures of control and prevention to be adopted in each property.