Orkideh Heidarnejhad, Shahabeddin Safi
Orkideh Heidarnejhad, Department of Pathobiology, Science and Research Branch, Islamic Azad University, Tehran, Iran
Shahabeddin Safi, Department of Pathobiology, Science and Research Branch, Islamic Azad University, Tehran, Iran
Key words: Culture, ELISA; Polymerase Chain Reaction (PCR); Diagnosis; Mycobacterium avium subsp. Paratuberculosis.
Mycobacterium avium subsp. Paratuberculosis is the etiologic agent of Johne’s disease in the cattle. JD is a disease with considerable economic impact on dairy cattle. It is prevalent worldwide, especially in developing countries including Iran. Rapid and accurate diagnosis of the infection is essential for controlling the disease. The present study compared fecal culture, ELISA and loop-mediated isothermal amplification (LAMP) for the diagnosis of MAP in dairy cattle. A total of 225 serum and fecal samples were collected from 14 dairy cattle farms in Tehran, Iran. The fecal samples were cultured in Harrold’s egg yolk agar with and without mycobactin j. DNA was extracted directly from fecal samples, too. Serum ELISA and LAMP were compared with fecal culture in terms of sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratio of a positive test result, and likelihood ratio of a negative test result. The sensitivity of LAMP and ELISA was 100%and 79%, respectively. Their specificity was 83.33% and 93%, respectively. Both LAMP (P < 0.001; k = 0.167) and ELISA (P < 0.001; k = 0.374) were in agreement with fecal culture as the gold standard. Moreover, LAMP and ELISA had 80% agreement with each other. This study suggests LAMP as a valuable and cost-effective tool for the early diagnosis of JD caused by MAP. Furthermore, due to inability of ELISA in detecting early stages of the disease and long and expensive method of culture, LAMP could be used alongside ELISA in cattle-wide screening for disease.