Study of the prevalence rate of John’s disease in Markazi province and evaluation of absorbed ELISA for adoption as a diagnostic method

    John`s disease or paratuberculosis is an infectious disease caused by Mycobacterium paratuberculosis and has been described in numerous ruminate species .In cattle, intractable diarrhea, emaciation, and hypoproteinemia in animals older than 19 months characterize the disease.
    The objectives of this study was to survey the prevalence rate of the John's disease in Markazi province and evaluation of the ELISA for detection of anti- Mycobacterium paratuberculosis antibodies and its possible adoption as a diagnostic method in field conditions . This study performed during the years of 2008 to 2009 and 1724 mature cattle older than 2 years age from 12 herds in Markazi province were enrolled in this study. Serologic testing was done for determine prevalence with a commercially (ID. Vet, France) available absorbed ELISA kit for antibodies against Mycobacterium paratuberculosis. In this study 274 cows in herds (15.5 %) were found to have positive sera. Minimum and maximum of contamination rate in herds were 4% and 58.6% respectively. Blood and histological samples were taken from 87 cows suspected to paratuberculosis in slaughter house. Sensitivity and specificity of absorbed ELISA for detection of John's disease in comparison with histophathology was 47.36% and 100% respectively. In conclusion, according to representing an easy-performing and low cost method, ELISA has shown to be satisfactory for diagnostic as screening test.