CAST Identifies Actions Needed to Eradicate Johne’s Disease in Cattle

January 1, 1999

A new scientific paper from the Council for Agricultural Science and Technology (CAST) identifies the issues that prevent eradication of Johne’s (pronounced yo-nees) disease in cattle. The CAST paper documents that an estimated 22 percent of U.S. dairy herds and 8 percent of U.S. beef herds are infected with the intestinal infection that is one of the most prevalent and costly diseases of dairy cattle and some purebred beef herds. A U.S. Department of Agriculture study estimates the disease causes $200 million to $250 million in economic losses to the U.S. dairy industry alone.

“Johne’s disease is complex and difficult to diagnose. Furthermore, it catches many cattle owners by surprise because affected animals may show the signs of chronic diarrhea and weight loss in a one-at-a-time fashion,” said CAST Johne’s Task Force cochairs Robert D. Linnabary of the University of Tennessee College of Veterinary Medicine and Gavin L. Meerdink of the University of Illinois College of Veterinary Medicine. “Work must be done to answer key questions related to control of the disease in cattle and determine what impact it may have on human health.”

The CAST paper identifies the following key issues that currently prevent eradication of Johne’s disease include:

Diagnostic inadequacies: Improved diagnostic tests are needed because current diagnostic tests detect less than 50 percent of infected animals at any single point in time. Therefore, repeated testing is required.
Lack of vaccine: An efficacious vaccine is not available and would be an important tool in Johne’s control.
Regulatory deficiencies: Uniform interstate disease definitions and regulations are needed to decrease confusion and litigation associated with animal movement.
Crohn’s disease link: A number of researchers have proposed that the same organism as Johne’s disease in cattle and other ruminants may cause Crohn’s disease in humans. Milk and milk products that are raw or inadequately pasteurized could provide a source of the organism.

Stringent Johne’s disease control programs in cattle herds will enhance dairy and dairy product food safety. To facilitate disease control recommendations, the U.S. Animal Health Association established the National Johne’s Working Group (NJWG) that is working to educate veterinarians and livestock producers, defining research priorities and assisting states with regulation development. The NJWG is also cooperating with the U.S. Department of Agriculture to develop national standards for Johne’s disease control.

The CAST paper verifies that policymakers must carefully consider the costs and benefits of a control program and who will bear the financial burden no matter whether future control strategies for Johne’s disease are implemented at the herd, state or national level. Policymakers and others may also face international trade issues stemming from the disease as countries adopt differing prevention and control strategies.

The complete paper, Johne’s Disease in Cattle, and other CAST reports are available at the CAST website at www.cast-science.org. CAST’s mission is to assemble, interpret, and communicate science-based information regionally, nationally, and internationally on food, fiber, agricultural, natural resource, and related societal and environmental issues to stakeholders–legislators, regulators, policymakers, the media, the private sector, and the public.

Further information about CAST is available – by phone at 515-292-2125 or by e-mail at cast@cast-science.org.

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