Frequencia de anticorpos contra o Herpesvírus bovino Tipo 1 (BoHV-1) em Bovinos leiteiros não vacinados no Estado do Maranhão

Abstract

The bovine herpesvirus type 1 (BoHV-1) has a worldwide distribution and it is described as a serious health problem producing productive and reproductive losses in infected herds. In this way, the research was realized with the objective to establish the frequency of antibodies against the BoHV-1 in the dairy farms of the state of Maranhão. Serum sanguine samples of 920 bovine females not vaccined against the BoHV-1 were analysed through the indirect ELISA technique. The study was realized in 92 dairy properties, belonging to 23 districts located in the regions of Açailândia, Bacabal, São Luiz Island, Imperatriz and Pedreiras. The serum samples were collected from females with or without clinical signals of the viral infection and stratified according to the age group (> 3 years, between 3 and 7 years and > 7 years). It was applied an epidemiological questionnaire during the sample collect to research the factors that could be associated to infection. From the 920 serum analysed samples, 71.30% (n=656) were positive, 17.40% (n=160) suspected and 11.30% (n=104) negatives. In the regional samples, they obtained frequency of 68.12% (n=109), 68.21% (n=191), 71.67% (n=86), 78.75% (n=126) e 72% (n=144), for São Luiz Island, Imperatriz, Açailândia, Pedreiras and Bacabal, respectively. In the 23 studied districts were found reagent animals, with detection of positive serological bovines in 100% of the properties. The frequencies of reagents by age group were 45.57% (3 to 7 years) 9.57% (<3 years) and 4.79% (> 7 years), the results indicate that age was statistically associated with infection (P <0.05). From the considered variables as risk factors, no one presented statistic significance (P<0.05) associated to BoHV-1 seropositivity. The obtained results demonstrated high percentage of virus frequency in the state of Maranhão’s dairy aptitude bovine flock. These findings indicate the need of systematic diagnosis accomplishment and the flock monitoring, beyond the implementation of control and prophylaxis measures, as a gradual removal of infected animals, setting on quarantine the new animals added in the proprieties, practicing serological exams and the use of vaccination.