Seroprevalence and risk factors for Bluetongue in rams of the Sertao and Borborema mesoregions, semi-arid of Paraiba state, Northeastern Brazil

The prevalence of antibodies against Bluetongue virus in rams of the Sertao and Borborema mesoregions, semi-arid of the Paraiba state, Northeastern Brazil, was determined, and risk factors for the infection were identified. The sampling was delineated for the determination of the prevalence of positive herds and seropositive animals for each mesoregion. Herds (primary units) were randomly selected in the Sertao mesoregion (n = 189) and in the Borborema mesoregion (n = 100). Within the primary units, all rams (secondary units) were sampled, resulting in 321 animals of the Sertao mesoregion and in 185 animals of the Borborema mesoregion. During collection, an epidemiological questionnaire was applied to each herd. For serological diagnosis, the agar gel immunodiffusion test (AGID) with antigen produced in the School of Veterinary Medicine of the Federal University of Minas Gerais was carried out. Herds with at least one positive animal were considered positive. In Sertao mesoregion, the prevalence of positive herds and seropositive animals were 11.6% [7.8% - 17.1%] and 8.4% [5.7% - 12.3%], respectively. In Borborema mesoregion, the prevalence of positive herds was 0.0% [0.0% - 3.6%] and the prevalence of seropositive animals was 0.0% [0.0% - 2.0%]. The risk factors associated with Bluetongue were lack of cleaning and disinfection of facilities (OR = 5.51), and administration of anti-parasitic treatment twice to four times per year (OR = 4.44).