The Wisconsin Department of Natural Resources has found a fatal brain disease in 10 deer in Dane and Iowa Counties.
During the November hunting season three out of 110 deer sampled in Mt. Horeb tested positive for transmissible spongiform encephalopathy, chronic wasting disease. Seven additional CWD-positive deer were found in 197 sampled deer from southcentral Wisconsin. The Wisconsin Department of Natural Resources plans to test about 300 more deer to further asses the span of the disease.
CWD is similar to mad cow disease in cattle and its analogous affliction in humans, Creutzfeldt-Jakob disease, which killed over 100 people in Britain. Scientists believe those who died ate beef products infected with mad cow disease.
Clinical signs of CWD, appearing in deer aged at least 14 months, include weight loss, wobbling, increased salivation and urination and a reduced fear of humans.
In Colorado, where CWD levels are high in wild deer populations, experts say no resident has come down with CWD in 16 years of surveillance. However, CWD is a member in a family of diseases defined by an incubation period of years to decades in humans, leaving the possibility humans have been infected but not yet diagnosed.
While experts believe humans are unlikely to die from eating deer with CWD, they advise people to avoid eating the brain, spinal cord, eyes, tonsils, spleen and lymph nodes of white-tailed deer and elk. These body parts contain high concentrations of the infectious agent, a renegade protein called a prion.
The World Health Organization recommends that no part of a deer or elk showing evidence of CWD be eaten.
\There's no evidence of CWD being transferred to humans, but we don't know for sure,"" said Judd Aiken, UW-Madison professor in the School of Veterinary Medicine.
Experts are quick to point out that CWD is different from mad cow disease, which researchers believe has been inadvertently transferred through beef products to humans, cats and some zoo animals. Unlike mad cow disease, CWD appears to be a contagious disease, transferred by contact among deer and elk, which leaves Wisconsin's DNR with ""a mess on their hands,"" according to Aiken.
Hunters provided the initial CWD-positive samples to Wisconsin DNR officials. Blood and brain tissues were sampled and tested for CWD as well as bovine tuberculosis and cranial abscessation syndrome. These are the first CWD-positive samples DNR officials have discovered in Wisconsin since they began asking hunters to donate brain samples for testing in 1999, said DNR Public Affairs Manager Bob Manwell.
""The good news is that we probably caught [CWD] early, which is always good for disease management,"" Manwell said.
It's too early to predict the economic impact CWD will have on deer hunting in Wisconsin, Manwell added.
The DNR announced they will begin sampling the brains of deer killed by cars, establish a CWD surveillance area in southwestern Wisconsin and identify areas of high deer concentration in addition to testing 500 deer in the Mt. Horeb area.
Aiken suspects that wild deer in Wisconsin got CWD from an infected deer or elk in one of southwestern Wisconsin's captive ranges.
""This wasn't a spontaneous thing,"" he said.
The Omaha World-Herald reported that Wisconsin's infected deer were killed seven miles from one captive white-tailed deer herd and 10 miles from another.
Scientists discovered CWD in a wildlife research facility in 1967. By 1997, deer and elk in South Dakota, Nebraska, Colorado, Oklahoma, Montana and Saskatchewan, Canada carried CWD.
Days before the Wisconsin DNR announced CWD was in the state, South Dakota found its first case of CWD in wild white-tailed deer. South Dakota's Department of Game, Fish and Parks began killing 135 deer in its state at the end of February.
State and federal officials began incinerating about 1,500 elk at nine facilities in Colorado on Feb. 8, Colorado's Department of Agriculture said, to prevent the spread of CWD.
Wisconsin is one of many states testing for CWD. Minnesota's DNR is testing deer on a smaller scale than Wisconsin. Michigan tested 452 deer for CWD in 1998. Iowa's Animal Industry Bureau requires elk breeders give samples for laboratory diagnosis of the death of any elk or deer over 18 months of age. Nebraska's Department of Agriculture requires deer and elk farmers to send brain samples within 24 hours of death for any deer or elk over 16 months of age.
For now, caution is the best defense.
