Comparative study of three diagnostic techniques for Enzootic Bovine Leukosis and analysis of the effect of concurrent diseases on the leukocyte formula

Abstract

Sensitivity and specificity of agar gel immunodiffusion (AGID) test, enzyme-linked immunosorbent assay (ELISA) and traditional polymerase chain reaction (PCR) for the diagnosis of Enzootic Bovine Leukosis (EBL) were studied in 65 Holstein cows. Besides, we report the percentage of positive animals that present lymphocytosis and changes in the leukocyte formula in two farms, from which only one of them has sanitary records. For the analysis of sensitivity and specificity, ELISA and PCR were considered as the reference methods. In the first case results were: 72 % and 100 % for AGID and 94 % and 77 % for PCR, respectively. When PCR was used as the reference method the results were: 45 % and 100 % for AGID and 61 % and 97 % for ELISA, respectively. The comparative analysis of these methods showed that PCR is more sensitive, followed by ELISA and AGID. Average lymphocytes counts are significantly increased in animals infected with the Bovine Leucosis Virus  (BLV), but the total number of lymphocytes is also affected by concurrent diseases.