The prevalence of paratuberculosis in the Plateau de Diesse region

: We analysed 595 cows in 20 herds for serological evidence of paratuberculosis with an ELISA procedure for which we had recently determined a sensitivity of 50% and a specificity of 98%, and we obtained an overall calculated real prevalence of 5.99%. In two herds with clinical cases of paratuberculosis, the calculated true prevalence of seroreactors was 21.47%. In 9 herds with clinical suspicion of Johne's disease, the rate was 4.23%, 9 herds without any clinical suspicion showed a mean prevalence of 0%. Whereas the trend was clear for groups of herds, the observed prevalence in individual herds varied from 0% to 17.9%, without obvious association with manifest clinical problems of paratuberculosis.