Comparitive study on the efficacy of ELISA and IS900 PCR for the diagnosis of Paratuberculosis in goats

Paratuberculosis, one of the chronic granulomatous enteritis that predominantly affects ruminants worldwide, is caused by Mycobacterium avium subsp. paratuberculosis (MAP). It is most efficiently diagnosed by MAP from faeces by Polymerase Chain Reaction (PCR). Serological tests like Enzyme Linked Immuno Sorbent Assay (ELISA) also provides a rapid and cost-effective alternative diagnostic tool. Present study was carried out to directly evaluate the sensitivity and specificity of ELISA (ID vet innovative diagnostics; France) using IS900 PCR as a gold standard. Serum and faecal samples were collected from 180 adult goats of either sex, from Malappuram and Thrissur districts of Kerala with unknown paratuberculosis status. Faecal samples were processed for direct IS900 PCR and serum samples were tested for MAP antibodies using Indirect ELISA kit. IS900 PCR detected 38 out of 180 confirmed to be shedding MAP. ELISA detected 22 out of 180 animals as positive. Overall, ELISA was 50 % sensitive and 97.9 % specific in comparison to IS900 PCR. The IS900 PCR outperformed ELISA in detecting animals potentially infected with MAP and is more sensitive than ELISA at detecting animals suspected of paratuberculosis. But, for early diagnosis of paratuberculosis in goats, ELISA can be done as easy and rapid farm level identification and IS900 PCR as individual confirmatory test.