The Three-Minute Outdoorsman: Wild Science from Magnetic Deer to Mumbling Carp

3. The Science of Chronic Wasting Disease

A L L T H I N G S D E E R 11 white-tailed deer populations are endangering any bird species, although locally numbers have likely been reduced. Around Minneapolis and St. Paul, an unlimited antlerless harvest has recently been allowed owing to the high survival of deer, which is not typical of the entire state. Of course, part of the motivation to cull the metropolitan herd is ironically to permit the maintenance of nonnative (i.e., ornamental) vegetation that deer like to browse in people’s yards. Also a lot of DVCs are occurring, which is generally bad, unless you own an auto body shop. Whether hunters can effectively manage the herds in the United States, Canada, and England remains to be seen. Our habitats have been altered by a large deer herd, in some areas larger than were historically present, and while that might not be permanent , it does affect other native animals such as songbirds. Further , when the native understory is reduced or eliminated by deer, it often favors spread of introduced plants like buckthorn. Couple that with habitat loss and fragmentation, pollution and feral cats, and it just keeps getting harder to be a bird! In this regard, a deer hunter just might be a bird’s best friend. 3 the science of chronic wasting disease and its relevance for management of white-tailed deer Chronic Wasting Disease (CWD) has been found for several decades in some western states but more recently has become established in the Wisconsin white-tailed deer population, especially in the area just west of Madison. Soon after it was discovered , CWD was big news because of the high fatality rate in infected deer. Naturally, people in neighboring states are wondering whether the disease will spread, and if so, what fate might t h e t h r e e - m i n u t e o u t d o o r s m a n 12 befall their white-tailed deer population. Will CWD lead to annihilation ? Will it be a minor inconvenience? Will it take huge sums of money to contain and control? Can people get CWD from eating infected deer? What we know about the disease is not yet sufficient to provide definitive answers to these questions. I think there is a lot of confusion about this important affliction of deer, and since my family and I consume large amounts of venison, I became personally interested in the subject and did a lot of digging into it. WhAT exAcTly is cWD? In a nutshell, CWD is a disease caused by a normal protein that “goes bad.” It results from the abnormal folding of an otherwise normal protein into one that is called a prion (short for “proteinaceous infectious particle”). Prions, or misfolded proteins, serve no useful function and build up in the body, lodging in cells, particularly in the brain, and cause death via a major neurological meltdown. Prion diseases in general are termed “transmissible spongiform encephalopathies,” or TSEs. The cow version is “mad cow” disease. In sheep, the prion-caused disease is scrapie. In humans, one version is Creutzfeldt-Jakob disease. Prions are not living organisms like bacteria or viruses. They do not reproduce themselves, as they have no DNA; that is, they do not divide or mate with other prions or contribute some of their material to another prion to produce a baby prion. They are in fact celibate! When a prion physically contacts a normal protein in a deer’s body, it causes the normal protein to misfold. Thus, spread within an individual deer is caused by direct contact between a prion and a normal version of the protein. In this way, prions are very much unlike other disease organisms we are familiar with. Furthermore, because the disease may not reach the final stages for eighteen months or more, a doe may have time to reproduce at least once, which may not be good for the population if she is genetically predisposed to getting CWD. A L L T H I N G S D E E R 13 hoW Do yoU KnoW if A Deer hAs cWD? A CWD-infected deer in the terminal stages exhibits a number of behavioral symptoms. Immediately prior to death, animals show listlessness, lowering of the head, repetitive walking in set patterns , excessive drinking and salivation, and grinding of the teeth. These behaviors are not...