Bovine babesiosis and anaplasmosis complex: diagnosis and evaluation of the risk factors from Bahia, Brazil.

Direct diagnoses were made by using - blood smears and nested PCR (nPCR) tests on 309 blood samples from crossbred dairy cattle in the municipality of Ibicaraí, Bahia. From diagnostic blood smear slides, the observed parasitic frequencies were 31.1% for Anaplasma marginale and 20.4% for Babesia sp. From nPCR diagnoses, they were 63% for A. marginale, 34% for Babesia bigemina and 20.4% for Babesia bovis. There were significant differences (P <0.01) between the two diagnostic methods (nPCR and blood smear slides). The compliance obtained from the kappa test was 0.41 and 0.48 for A. marginale and Babesia sp., respectively. The tick samples from the six farms analyzed using nPCR were only positive for A. marginale. Evaluation of the risk factors relating to the presence of ticks and the age of the animals showed that there was a significant association (P <0.01) with the frequency of animals infected with both pathogens. Therefore, under the conditions studied, nPCR proved to be a good tool for diagnosing the agents of the bovine babesiosis and anaplasmosis complex because of its sensitivity and specificity in comparison with blood smears. The municipality of Ibicaraí is an area with endemic prevalence of bovine babesiosis and anaplasmosis confirmed by nPCR and A. marginale is the main agent of the disease.