Molecular detection of bovine leukosis virus in naturally infected dairy and dual-purpose cattle in Mexico.

The objective of this study was to determine the prevalence of bovine leukosis virus (BLV) in specialized and dual-purpose dairy cows located in the central zone of Veracruz state in Mexico, using endpoint polymerase chain reaction (PCR). The study population consisted of 307 specialized dairy cows and 95 dual-purpose cows from 13 municipalities located in the study area. All cows were apparently healthy and ≥ 3 years old. Cows were stratified by age (3 - 5, 6 - 8 and ≥ 9 years). The overall prevalence of infection was 6.96%; the calculated prevalence in dairy cows was 7.82% and in dual-purpose cows it was 4.21%. The municipality with the highest proportion was Acajete (14.28%), followed by Huatusco and Tomatlán (11.53%). The association analysis confirms the infection's independence to the cows' productive purpose. The results by age strata were 3 - 5 (4.60%), 6 - 8 (8.00%) and ≥ 9 (18.40%) with X2 = 9.96, with an odds ratio of 4.68 for the stratum ≥ 9 years with a significant difference. The present study determined the prevalence of proviral DNA of BLV in dairy and dual-purpose cows in six municipalities in the central zone of Veracruz state, Mexico, using endpoint PCR.