Comparison to Methods; Serum Antibody ELISA and Fecal Nested-PCR to Diagnose Mycobacterium avium Subspecies Paratuberculosis Subspecies Infection in Cattle

Mycobacterium avium subspecies paratuberculosis is the cause of a common disease in dairy herds. Early diagnosis of paratuberculosis infection can improve Johne’s disease control programs.

This study aimed to compare the sensitivity, and specificity to methods; blood serum ELISA and stool Nested-PCR for the detection of Mycobacterium avium subspecies paratuberculosis infection in dairy cattle.

A commercial ELISA kit was used to perform the absorbed ELISA test, which was conducted after exposing serum samples to Mycobacterium phlei antigens to limit cross-reactions. Nested-PCR test was performed using nucleotide sequences related to specific MAP gene fragments, i.e. IS900.

As a result of the ELISA antibodies kit, out of the total 2203 serum samples, 112 samples were positive (5.08 %) and 2091 samples were negative (94.92 %). The results of Nested-PCR tests of rectal feces showed that out of 59 cows with the positive results in serum ELISA, 47 (79.66 %) samples were positive and 12 (20.34 %) samples were negative. Moreover, out of 31 cattle with a negative result on the ELISA test, 15 (48.38%) and 16 cattle (51.62 %) had positive and negative results, respectively, on the nested PCR tests of the feces samples.

Due to the low sensitivity of PCR compared to ELISA, the positive and negative predictive values, and the accuracy of ELISA test, as well as the high cost and time-consuming nature of PCR and the need for more and more complex facilities than ELISA, the authors concluded that ELISA is a more suitable method for screening and epidemiological studies than PCR.