Chronic wasting disease (CWD sometimes called mad deer disease) has spread among deer, elk, moose, and other cervids. CWD was first identified in 1967 in a captive mule deer on a governmental research station. By 2000, the disease had spread to 5 states and 1 Canadian province. In 2018, it was present in 26 states and 3 provinces. And CWD continues to spread; it was most recently found on the west side of the continental divide near elk winter feeding grounds. This uniformly fatal disease causes the animals’ brains to deteriorate as they slowly waste away.
CWD is currently labeled as either a true prion or a “prion-like” disease that can be spread through blood, saliva, urine, and feces. The prions remain infectious for years in the soil and can withstand extremely high levels of heat, radiation, and formaldehyde. Transmission of CWD is primarily via direct contact by a healthy animal with an infected animal’s bodily fluids but transmission is also aided by baiting and feeding animals which encourages animals to congregate. Other factors include improper disposal of dead remains, and human transport of dead and live deer (the latter usually by game farms). This movement of live animals between such farms has been implicated as a cause of transmission in 10 states, Canada, and Korea.
As CWD spread across the country, it was tracked. Hunters were advised to submit samples for testing but were also told that the disease was unlikely to be infectious to humans and there was no need to worry about eating game meat. Valid tests can only be done at federally approved laboratories, and testing is somewhat slow. It also has some false negatives as it cannot detect the disease in its early stages. As a result, much of the meat is eaten before the results are in. The Alliance for Public Wildlife estimates that 7-15,000 infected animals are eaten annually, a number growing by perhaps 20% each year.
The big concern at this point is that studies now strongly suggest that CWD IS infectious to humans. Squirrel monkeys and rats with some added human genes did acquire CWD. As did a monkey species closely related to humans. In the latter study, macaque monkeys eating the equivalent of a 7-ounce venison steak/month from an asymptomatic deer showed signs of prion disease. Of course, these animal studies are small and subject to a variety of criticisms but nonetheless strongly suggest that we humans can acquire CWD from the meat of any cervid with CWD, symptomatic or not. And if true, there will be the concerns about further spread through our blood supply if those eating wild game donate blood.
And, although not discussed anywhere to my knowledge:
Game is increasingly a component of dog and cat food. As a rule, it’s an attractive alternative to feeding a pet factory farmed animals but given the presence of CWD, it may not be the best choice unless carefully sourced.
Deer antler velvet is a component in some Chinese herbal formulas. The velvet used in those does contain brain tissue and may well also be of concern.