Comparative evaluation of improved ‘Modified Microscopic Test’ with traditional microscopy, indigenous ELISA kit, fecal and blood PCR for the diagnosis of Mycobacterium avium subs paratuberculosis in goat herd endemic for Johne’s disease

Abstract

Presently available tests for the diagnosis of Mycobacterium avium subspecies paratuberculosis (MAP) infection were frequently used by several laboratories in developed countries, however, low income countries further required a test of affordable price or cost for small ruminants.  Therefore, in present study five test, ‘Hexadecyl Pyridinium Chloride (HPC) processed fecal microscopic’ test (test 2),  traditional microscopy (test 1), ‘indigenous ELISA kit’ (test 5) and ‘fecal IS900 PCR (test 3) and blood IS900 PCR (test 4) were compared for the detection of MAP infection in goat herd endemic for Johne’s Disease (JD). The 79.6, 100.0, 44.4, 12.9 and 98.1% goats were positive in tests 1, 2, 3, 4 and 5, respectively. Sensitivity of tests, 1, 2 and 5 was superior than PCR based tests (3 and 4). Specificity of tests, 1 and 2 may vary from lab to lab depending on experience and expertise of user. Decontamination of feces in test 2, with Hexadecyl pyridinium chloride further concentrated MAP bacilli, therefore sensitivity of test 2 improved significantly and can be a ‘good screening test’ for the surveillance of JD in herds and flocks. This ‘HPC processed fecal microscopic’ test was efficient for the diagnosis of MAP and monitoring of shedders in infected animals. Present study reported that Test 2 in combination of Test 3 is a cost effective and quick test as compared to other tests, therefore can be used for the screening of MAP infection in developing and under developed poor countries for small ruminants, where cost is limiting factor.