The prevalence of bovine leukaemia virus (BLV) was determined, through the anti-BLV serum antibody test, in 661 samples collected in 16 dairy herds from four municipalities in the micro region of Manaus, at the Amazonas state. The agar gel immunodiffusion test with an envelop glycoprotein virus-antigen (gp-51) was used as a method of diagnosis the infection or the presence of anti-BLV antibodies transferred passively by the colostrum to calves up to six- month-old.. ll herds were positive for the BLV test. The overall prevalence was 8.9%. When the calves less than six-month-old were excluded a rate of 9.6% (58/604) infection prevalence was found. The influence of the age and sex factors on the prevalence of BLV were analysed by the two-proportion test. Higher prevalence rate was found in cattle older than 12-month-old as compared to the younger calves. No sexual effect was found.
Bovine Leukosis Virus; Prevalence; Dairy cattle; Amazonas state; Brasil