By Staff
Last week we delved into Chronic Wasting Disease that was recently discovered here in Michigan. That was a single captive deer and there is hope the disease remained within the pen. Another deer afflicting disease we have no hopes of dodging is Bovine Tuberculosis. Michigan is now infamous for its Bovine TB infected deer but most hunters and nature enthusiasts know little about this disease. There are three types of tuberculosis, Avian, which is found largely in birds, Human, reserved for us two legged types, and the highly transmittable Bovine, normally associated with cattle but seemingly able to infect just about any animal.
TB is historically very rare in deer. In fact, until its outbreak in Michigan in 1994 there were only eight recorded cases in the entire United States. TB primarily affects the lungs and is not necessarily fatal. In its more advanced stages tan or yellow lesions appear on the lung surfaces and chest cavity. However, these are only noticeable in casual observation less than half the time. In deer there is no preventive vaccine and no cure. It is spread primarily by exchange of respiratory excretions where deer cough and sneeze on each other, such as at feeding stations or bait piles. It can also be contacted by eating raw contaminated meat. In this fashion it is transmitted to predators and scavengers such as bears, coyotes, raccoons, opossums and red fox, all of which have been found with TB here in Michigan. Very rarely Bovine TB can infect humans. There have only been two human cases of Bovine TB here in Michigan. One was an elderly gentleman where it was discovered after he died of other causes. The second was a hunter who cut himself while butchering an infected deer. He recovered.
So just how bad is this TB stuff? Actually, from the overall deer standpoint, not all that bad. Since its discovery in 1994 162,000 deer have been tested of which 594 had TB. Of those, 97% came from a five county area in the northeastern Lower Peninsula where the disease first surfaced. The remainder came from nearby so the disease has not significantly spread as has been feared it might. The one exception came late last year where a deer shot in Shiawassee County in southeastern Michigan tested positive. Officials are trying to find out if this deer somehow came from the TB area or if it was infected from some other source. Intensive testing around this new occurrence has found no other cases.
Perhaps the most significant impact of TB in our deer is upon the cattle industry. Cattle from states known to have TB must be proven TB free before they can be marketed. In addition, farmers must continually test to be sure their herd hasn't been infected by deer. If that occurs, all the cattle are destroyed. These added expenses make it difficult for Michigan producers to compete with TB free states.
Michigan's strategy to deal with and hopefully eliminate Bovine TB is multi-pronged. Steps were taken to reduce the overall population within the infected area so the deer weren't in such close contact with each other. This included allowing more hunting harvest and issuing permits to shoot deer on private property year around. This has reduced the deer population in the infected zone by 27 percent. To further prevent close contact, feeding and baiting within the area was banned. However, them's some bullheaded hunters up there and violation of the baiting ban quickly became a sport in itself. Of course, with CWD rearing its head baiting is now banned in the entire Lower Peninsula. For the near future, a quick, easy field test for TB has been developed and there are plans to begin live trapping and testing deer, culling the infected ones. There are also hopes of a vaccine on the horizon. USDA scientists working on a preventive vaccine are seeing some promising results. We must do our part, too. Learn to hunt without bait, leave the food in the barn and let winter run its course as nature intended and quit putting salt blocks in the yard and maybe we can lick these diseases. Carpe diem.