[Bacteriological investigations about paratuberculosis in dairy herds in Switzerland]

In Switzerland clinical bovine paratuberculosis is registered sporadically with on average seven outbreaks per year. Our present studies are aimed to investigate the prevalence of Mycobacterium avium ssp. paratuberculosis (MAP)-infections in the Swiss cattle population and, therefore methods to culture MAP from bovine feces as well as a commercially available ELISA to detect MAP-specific antibodies are evaluated by using fecal samples and blood sera from herds with cases of clinical paratuberculosis. A series of molecular methods i.e. PCR-coupled RFLP analysis of the IS1311-insertion element of M. avium, PCR-coupled RFLP-analysis of the mycobacterial rpoB-gene, and DNA analysis of the mycobacterial 16S rRNA gene are used to identify mycobacterial isolates grown from bovine feces. Up to now, MAP was detected by culture in 12 of 155 (7.7%) animals from herds with paratuberculosis. A rather striking result is the finding of atypical mycobacteria in feces of 75 cattle (48.3%). Among these isolates, M. avium ssp. avium, M. thermoresistibile, and M. hassiacum/M. buckleii have been identified so far.