[Observations on the control and eradication of paratuberculosis in dairy herds]

Johne's disease is widely seen in dairy herds in Germany. Estimates based primarily on epidemiological surveys in neighbouring states assume that 5 to 15 % of German herds are infected. In the past three years several authors have reported that the causative agent of Johne's disease, Mycobacterium avium subspecies paratuberculosis (MAP), is found ubiquitously in the environment and can be isolated from a number of different animals, including non ruminants. These results imply that MAP should be considered an environmental pathogen. Based on this assumption a concept for control and eradication of Johne's disease is presented aiming at minimizing the future spread of disease and reducing environmental contamination with the pathogen at low costs. The concept includes the classification of herds based on an bulk milk ELISA followed by a robot-compatible bulk milk PCR in ELISA-positive herds only. Due to the comparatively low costs combined with the high specificity of the approach a detection of heavily infected herds ("tip of the iceberg") all over the country would be possible; based on the eradication of strong shedders in these herds the input of MAP into the environment would be reduced considerably.