Comparison of the absorbed ELISA and agar gel immunodiffusion test with clinicopathological findings in ovine clinical paratuberculosis
Clarke, C.J.; Patterson, I.A.; Armstrong, K.E.; Low, J.C.
Veterinary Record 139(25): 618-621
1996
ISSN/ISBN: 0042-4900 PMID: 9123786 Document Number: 463491
Thirty-two sheep with clinical paratuberculosis and 43 normal, healthy control animals were tested for serum antibodies to Mycobacterium avium subspecies paratuberculosis with the absorbed ELISA and agar gel immunodiffusion (AGID) test. All the sheep were examined PM and the diseased cases were categorised as having either multibacillary (lepromatous) or paucibacillary (tuberculoid) intestinal lesions. The ELISA and AGID test were highly sensitive when testing the multibacillary group (86.4% and 100%, respectively) but the sensitivity of the tests in the paucibacillary group was significantly lower (10 to 50% and 30%, respectively). These findings were related to the ELISA optical density readings, with the multibacillary samples having values significantly greater than those of the paucibacillary and control groups, and the optical density values appearing to correlate with the numbers of mycobacteria present in the intestinal lesions. These results indicate both the usefulness of serological testing in the diagnosis of the multibacillary form of paratuberculosis and the difficulty in identifying animals with the paucibacillary form of the disease.