Johne's Disease (JD)
JD is a chronic granulomatous inflammatory intestinal disease of ruminants that results from infection with Mycobacterium avium subspecies paratuberculosis (M. paratuberculosis or MAP).
First identified over a century ago, JD is now recognized to be a serious economic and animal health problem in domesticated ruminants (such as dairy and beef cattle, sheep, and goats) throughout the world. It results in more than $200 million in annual losses to the United States (US) dairy industry each year with additional losses incurred by the other species.
The growing recognition of M. paratuberculosis infection in wildlife species is also of considerable concern. Similarly, recent evidence of the presence of M. paratuberculosis in retail milk sources is of concern from a milk quality and potential food safety standpoint.
JD remains a major concern for producers with very high prevalence rates (68% of all US dairy herds and 95% of those with over 500 cows have at least one JD positive animal (REFLINK).
There have been considerable ongoing efforts made to identify knowledge gaps, define research priorities, and develop recommendations for implementing JD control measures in the field.
For instance, a 2003 report from the National Research Council of the US National Academies of Sciences on JD comprehensively reviewed the literature, identified major gaps in knowledge, and provided clear recommendations for future research priorities and strategies for the prevention and control of JD.
In brief, the report concluded that JD is a significant animal-health problem whose study and control deserves high priority from the USDA. It was recognized that the problems associated with JD stem from:
- Difficulties in diagnosis because of an unusually long incubation period and a lack of specific and sensitive diagnostic tests for detecting early infections;
- A lack of vaccines or other effective measures for infection control; and,
- A general lack of awareness of the disease and its true economic and animal-health consequences by producers and veterinarians.
The report made 25 specific recommendations regarding implementation of strategies for the control of JD, educating and training of producers and veterinarians, and filling of key gaps in knowledge relating to JD.
In 2005 and 2006, specialty working groups were formulated by the USDA-APHIS-VS and the Johne’s Disease Integrated Program (JDIP; www.jdip.org) to review knowledge-gaps and opportunities for research, extension and training in JD. Some of the community needs that were identified as gaps included:
- Development of new and improved diagnostics and candidate vaccines;
- Improving research efficiencies by developing shared resources and guidelines for basic and translational research in JD; and,
- Developing strong education and extension programs.