This one causes diarrhea, wasting and death, primarily in dairy cattle. Some scientists are raising the alarming possibility that the microbe causing the illness may be passed on to humans via milk. There has been accumulating evidence in recent years that the bacterium causing the disease, known as mycobacterium avium subspecies paratuberculosis, or MAP, has some association with Crohn's disease and may play some role in its development. Crohn's is an often severe gastrointestinal illness affecting at least a half million Americans. It causes symptoms such as abdominal pain, disabling diarrhea, and loss of appetite.
Drug treatments are limited and there is no cure.
Complex, On the Rise An extensive search of the literature on Johne's disease and Crohn's, and interviews with experts reveals that the issues surrounding the possible animal link to human disease are, to say the least, complex. What is very clear is that Johne's disease, which also affects sheep, goats, deer, antelope and llamas, is on the rise, and that infected cattle continue to be used for milk production and are then slaughtered, mainly for ground beef, according to the dairy and beef industries, and veterinarians studying the disease. While the full extent of the disease is difficult to assess because of limited testing for it, federal officials and the dairy industry estimate on the basis of a 1996 national survey that some dairy cattle are infected in about 22 percent of herds across the country. Dr. Michael Collins of the School of Veterinary Medicine at the University of Wisconsin, on the basis of discussions with key researchers across the country, including those at a meeting held in Colorado Springs late last month of a national Johne's monitoring group, estimates that the number of herds affected is much higher. Vaccines Ineffective, No Cure Anti-microbial treatments for Johne's do not cure the disease and a vaccine is not a reliable way to stop it.