Comparative efficacy of certain diagnostic tests on detection of paratuberculosis in cattle

Abstract

A study was conducted to compare the efficacy of ZN acid fast staining, and IS900 PCR to detect bovine paratuberculosis. Indirect ELISA was also performed to assess the seroconversion. A total of 58 faecal samples and sera samples were collected from University Livestock Farm, Mannuthy; Cattle Breeding Farm, Thumburmuzhy; Livestock Research Station, Thiruvazhamkunnu and one private farm in Thrissur. The faecal samples were used to conduct the ZN acid fast staining and IS900 PCR. Indirect ELISA was performed using the sera samples. Among 58 samples collected, 10 samples (17.24 per cent) were positive in IS900 PCR and 6 samples (10.34 per cent) were positive in ZN acid fast staining. Two samples (3.45 per cent) were positive in indirect ELISA. The two ELISA positive samples were positive in IS900 PCR and one was positive in ZN acid fast staining. Among the six acid fast positive samples, five samples were positive in IS900 PCR but one sample was negative. Although IS900 PCR detected maximum number of positive samples than acid fast staining, statistically there was no significant difference. Since the seroconverted animals are very less at the initial stage of infection, indirect ELISA cannot be used for serodiagnosis for subclinical bovine paratuberculosis. ZN acid fast staining is a rapid, cheap, easy and field oriented diagnostic technique for detecting subclinical paratuberculosis. At the same time, IS900 PCR is a rapid and sensitive molecular based method for detecting subclinical paratuberculosis. Hence it was concluded that a combination of ZN acid fast staining and IS900 PCR was found to be very useful in diagnosing subclinical cases of bovine paratuberculosis.