Chronic wasting disease, or CWD, is a member of the transmissible spongiform encephalopathy (TSE) family of brain diseases that affects deer and elk in North America. Even scientists on the front lines of research don’t fully understand TSE diseases. The biggest theory to date is that an abnormal type of protein called a prion, which acts upon normal proteins in the brain and causes them to form toxic aggregates that destroy brain cells and tissue, causes this disease. The brain tissue becomes riddled with sponge-like holes, hence the term spongiform. These diseases can be transmitted from animal to animal, although in most cases, scientists are not certain how it occurs. It is similar to the widely know “Mad Cow Disease” or Bovine spongiform encephalopathy, that was all over the news not so long ago. The disease causes animals to look as if they are wasting away, appearing to be skin and bones.
It was first discovered in captive cervids at a wildlife research facility near Fort Collins, Colorado, in 1977 by a group of scientists. Shortly thereafter, it appeared in mule deer at a sister research station near Wheatland, Wyoming. It is unknown if CWD existed in the wild before, but it has now been found in a 14,600-square-mile area of Wyoming, Colorado, and a small part of Nebraska. In this area the disease affects about 15 percent of mule deer and 1-2 percent of elk. To the south of this area, which is the heart of the infection, it is said that infection rates have been seen as high as 30 percent which is the highest rate of infection of any other TSE.
Most of the outbreaks are believed to be related to game farms and the spread of the disease is quite slow. Starting in 2002 random testing has been occurring in harvested (hunted) deer and elk. Though it’s spread has reached several states including Colorado, Wyoming, South Dakota, Mississippi, Michigan, New York, Oklahoma, Illinois, West Virginia, Montana, Nebraska, Kansas and two Canadian Provinces, it is unclear that harvested meat has had any affect on human consumption. There is still a lot to learn about this terrible disease. To learn more about CWD here are some more articles from Field & Stream Magazine click here.