Estimation of the prevalence of Mycobacterium avium subsp. paratuberculosis by PCR in sheep blood

Abstract The prevalence of Mycobacterium avium subsp. paratuberculosis ( Map ) infection in sheep was estimated by blood PCR. One thousand and five hundred sheep belonging to 150 sheep flocks of Tras-os-Montes e Alto Douro (TMAD, Portugal) were studied. Animals were divided into two groups of five sheep each according their health status: “apparently healthy animals” and “paratuberculosis suspect animals”. Samples were pooled in groups of five. PCR detected Map DNA in 56 (18.7%) pool samples. The overall individual prevalence of Map in this study ranged from 6.4% to 15.4%. Map was found in 20.7% pooled samples from apparently healthy and in 16.7% pooled samples from suspect animals. The aim of the present study was to estimate the prevalence of ovine paratuberculosis using a PCR pool screen approach. The results showed that a simple blood PCR method could be reliably performed on pools of five samples in order to estimate the prevalence of Map infection in the ovine population.