The efficiency of ELISA and PCR in detecting subclinical paratuberculosis in the Saudi dairy herds

This study was aimed to reveal the presence of John's disease in the Saudi dairy herds using the newly developed diagnostic tests, ELISA and PCR. A total of 687 serum and fecal samples were collected from dairy cattle of four different ages, one, two, four and six years age cattle of three geographically different dairy farms. IDEXX ELISA revealed 15 (2%) positive samples and 17 (2.5%) samples were inconclusive. PCR test were used only to test 62 ELISA-negative samples that their OD readings were the highest and all the inconclusive samples. The PCR disclosed more positive samples (22/62 = 32%), interestingly among the samples of the two-year old cattle. The study has conclusively confirmed the presence of the disease in the Saudi dairy herds. It has also approved the effectiveness of ELISA and PCR tests in revealing the MAP infection at the subclinical stage.