Diagnosis of Johne's disease

Abstract

Johne's disease is a chronic and highly contagious wasting disease of all ruminants caused by Mycobacterium avium ssp paratuberculosis (MAP). Major clinical signs include weight loss, pipestream diarrhea, edema, decreased milk production, and eventually death. In the US, Johne's disease affects ~70% of dairy herds, costing the industry up to $250 million per year in production loss. An estimated 5 to 10% of beef herds are also affected. Johne's disease represents a significant problem in goat and sheep herds as well; however, no serologic tests are currently licensed by the USDA for small ruminants.