Scrapies in sheep, mad cow disease in cattle, Creutzfeldt-Jakob disease in humans and chronic wasting disease (CWD) in cervids — what do these fatal diseases all have in common?
Prions are mutated/misfolded proteins that inhabit the brain. When these misfolded prions come into contact with normal proteins, they then trigger the healthy proteins to misfold and become infectious. Eventually these prions accumulate and cause extreme central nervous system damage in the infected animal.
The cervid form of prion mutations has been an avid topic of discussion in the state of Michigan over the last couple of years — chronic wasting disease (CWD). As of August 2018, 23 states in the United States have confirmed cases of CWD in their free ranging deer herds (CDC). In addition, the disease has been found in Norway, Finland, and South Korea. While Colorado was the first U.S. state to confirm a case in the 1960’s, it quickly spread to surrounding areas. These include Wyoming, South Dakota, Oklahoma, Nebraska, Wisconsin, New Mexico, and the list goes on. Michigan however, is one of the most recent states to confirm CWD in their deer herd in 2015.
While other states like Wisconsin have had over 4,000 deer test positive for the disease, Michigan still has lower detection rates (about 105 total) (WIDNR). It is unknown whether this is due to the fact that it was discovered much later in Michigan or if there are not as many infected deer yet — meaning there is still hope to try and prevent the disease from spreading.
CWD is a resilient disease that spreads through direct animal-animal contact, bodily fluids, and infected soil and plants. Once the misfolded prions are established in an area, the risk remains for decades. Prions that are shed onto the soil from cervid saliva, blood, urine, carcass remains, etc. can remain in the soil for up to 3 years, possibly even longer! The plants that then grow from this soil contain the misfolded prions as well. Any member of the cervid family can contract CWD. This includes moose, elk, several deer species and caribou.
An infected animal will experience weight loss, a loss of their fear of humans, excessive drooling and salivating, and overall deterioration. The incubation period of the disease can take years, meaning a sick animal may express no symptoms at all, making it even harder to monitor the disease. Because the related disease, mad cow disease, jumped host species from cattle to humans in the early 1900’s, it is not recommended to consume venison that has been tested and confirmed with CWD.
CWD is always fatal and very difficult to rid; however, research on combative vaccines and treatments are being investigated. In November 2018 a study by Judd Aiken was published in the PLOS Pathogens Journal claiming that a certain compound (humic acid) of organic soil matter was able to degrade CWD prions in mice. Depending on a soils composition, different binding properties to these prions can occur. This in turn affects their infective properties.
So while there is still hope in the forefront of medicine, what can we do to aid in the spread of this always-fatal disease? If you are a hunter, keep hunting! State agencies need you to check your deer so that disease research can continue. Scientific advances require your participation
If you don’t hunt, keep an eye out for deer acting odd. Report any roadkill you find so that it can be picked up as soon as possible (remember those prions can stay infectious in the soil for years!). While a lot of other things can cause cervids to act strange, it is always better to be safe and report it, than sorry and spread it even farther.
Consider volunteering at your local deer check station or wildlife agency to help with the monitoring efforts as well as to learn hands-on what the implications for your state’s deer herd are. Last but not least, help educate. Education and spreading the knowledge of what this fatal disease could mean for wildlife in your state is the most important thing. The first step is knowing what it is. The next step is figuring out how to fight it.
To follow CWD monitoring efforts and results in your area go to your state wildlife agency’s web page. Michigan’s is as follows:
To see what the Centers for Disease Control (CDC) has to say about CWD:
What is another wildlife disease you have heard of and how is it being treated/taken care of?