Monitoring of enzootic bovine leukosis in dairy cattle from the Pitangueiras region in São Paulo, Brazil

Abstract

Serum samples of dairy cows from the region of the municipality of Pitangueiras, State of São Paulo, were investigated for the possible presence of precipitating antibodies against the gp51 antigen of Enzootic Bovine Leukosis. Blood samples were obtained from animals belonging to seven rural properties which were followed up on a yearly basis, from 1992 to 1995. A total of 140 serum samples were analyzed in 1992. Of these, 24 (17.1%) reacted positively, 21 (15.0%) were suspect and 95
(67.9%) were negative. In 1993, of the 122 samples tested 25 (20.5%) were positive, 8 (6.6%) were suspect and 89 (72.9%) were negative. In 1994, of the 135 samples tested, 45 (33.3%) were positive, 19 (14.1%) were suspect and 71 (52.6%) were negative. Finally, 119 samples of serum were investigated in 1995, 60 of which (50.4%) were positive, 11 (9.2%) were suspect and 48 (40.4%) were negative.These results demonstrate that a sharp increase in the prevalence of Enzootic Bovine Leukosis occurred during the experiment. From the viewpoint of Animal Sanitary Defense, the growing dissemination of the disease in the studied population serves as a warning about the epidemiologic behavior and about the evolution of the diffusion of the disease in Brazil.