[Serological prevalence and evaluation of the risk factors of bovine enzootic leukosis in the Bogotá savannah and the Ubaté and Chiquinquirá Valleys, Colombia].

The authors present the results of a study to determine the serological prevalence of the enzootic bovine leukosis virus among dairy cows in the Sabana de Bogotá region and the Ubaté and Chiquinquirá Valleys, the principal dairying areas of Colombia. Samples were taken from 919 animals selected at random from 420 farms in 51 municipalities, in accordance with a statistical sampling procedure developed previously, based on the cattle census maintained by the Animal Health and Disease Control Office of the Instituto Colombiano Agropecuario, and the recommendations for prevalence studies of the Pan American Health Organization. The double gel diffusion technique with gp-51 antigen was used. Serological prevalence averaged 45.28% (ranging from 42.07% to 48.49%) with a confidence level of 95%. In addition, a survey was conducted to determine how much those in charge of herds knew about the disease, and to establish the incidence of certain risk factors possibly associated with distribution of the causal agent. Data obtained from 232 completed questionnaires showed that only 54.6% of farms received professional assistance. Of these, 6.6% received constant assistance, 4.4% received visits every fortnight, 51.8% received monthly visits, 14% received visits every other month and 22.95% received occasional visits.