A mysterious and insidious pariah of nature…
Needless to say folks, in order to properly write this article I have to use some big words which I have trouble even pronouncing much less being sure I spell everything correctly, and I’ll try to keep matters in order. Transmissible spongiform encephalopathy (TSE) is a fatal disease which involves a misfolded protein known as a prion to cause normally folded proteins to become misfolded, and affects the nervous system and body tissues. Typically, certain types of TSE are species related, but recent times have shown what is known as a crossover of the species barrier can occur.
An example is bovine spongiform encephalopathy (BSE) which is also known as “mad cow disease” that was discovered in the United Kingdom in the 1980s. It is believed to have been caused by scrapies (a TSE per sheep and goats that is a disease which symptoms were known to be around as far back as 1732 – the name derived from sick sheep rubbing on things and the wool is “scraped” off) infected sheep being processed in the same slaughterhouse facility as cattle, then contaminating a byproduct known as bone meal, that was used as a concentrated supplement for cattle feed, causing a crossover of the species barrier.
This would in turn would cause “variant Creutzfeldt-Jakob disease” (vCJD) in humans who had eaten meat (and body organs) of BSE infected cattle. This alarming evidence represents a species barrier crossover of sheep to cattle to humans and how a lot remains to be a mystery continually being researched.
Prions are passed on by infected animals in what is referred to as “shedding” through feces, urine and saliva. Prions are truly tough and can contaminate the soil for decades and are even absorbed by plants. Deer grazing on the contaminated soil (and plants) and drinking from associated watering spots, as well as close association to each other can be readily introduced to CWD. A critical part about CWD is that prions can be shed for a couple years or more by infected animals that appear healthy without showing the apparent signs (living skeletons) of the disease until just prior to dying from it.
CWD (which can affect deer, elk and moose – the bigger species take longer to show signs of the disease) has a tendency to “travel on wheels” and captive elk from Colorado that were shipped to elk farms in Saskatchewan and Alberta transported the disease in a big leap across the border. Elk sent from Saskatchewan to elk farms in South Korea brought CWD across the ocean. Captive mule deer sent from Denver to the Toronto Zoo brought CWD with them. Also brought on wheels are infected animals (which appear healthy) killed by out of state hunters who transport the meat (and sometimes whole carcasses) back to their home areas and improperly dispose of matters (such as dumping it in the woods to get rid of it) and parts relating to the brain (per a trophy cape with head intact) and spinal column (what can be left over after deboning) which are true culprits for containing infectious prions and contaminating the soil at a dumping site (for years to come).
When you study a map of CWD and how it is suddenly realized in various states, it is quite clear that it was often brought there in some form, on wheels. This is no doubt what occurred in Michigan when a captive whitetail deer was diagnosed with CWD in 2008 in the southwestern part of the state. All the remaining captive cervids in this facility were eliminated and thoroughly examined, and none had CWD.
Then a free ranging (wild) gaunt and sick deer near Lansing was euthanized by a Meridian Township Police Officer in 2015. Tests revealed it had CWD and a plan of action was immediately put in place by state officials (actually a CWD response plan was put in place if CWD occurred in 2002, and revised in 2012 by wise and far thinking state officials). Because a large portion of Meridian Township is urban related, skilled sharpshooters were required to kill some of the deer for testing as well as in bringing the deer numbers down (some shooting was required to be done at night by state sharpshooters to be effective in a suburban environment). Eight more deer proved positive for CWD, and DNA analysis discovered all nine deer were related in some form. The most likely source of CWD to this area was probably the result of improperly disposed deer parts from a CWD infected deer killed in another state, but that mystery may never be solved.
Then in 2017, samples from a whitetail deer in a captive cervid facility in Mecosta County proved positive for CWD. Remaining deer in the facility were eliminated and tested but none had CWD (not much information is available due to an ongoing investigation). One free ranging (wild) deer tested positive for CWD in Montcalm County as well. So Michigan to date as I write this has had a total of 11 deer test positive for CWD, nine in close vicinity, and two further out and spread apart. I can only guess what that may mean in the future.
What really surprised me was when a CWD infected reindeer was recently discovered in southern Norway (by a helicopter doing a GPS study of reindeer). Norway has strict laws which prevent any importation of cervids which makes the arrival of CWD a true mystery. However sheep are pastured as well in the reindeer territory and therein may lay the possible link which I’m sure is being looked at. To date Norway has a total of two reindeer and two moose that have tested positive for CWD and officials are taking immediate measures in an attempt to eliminate the disease.
I was at the Natural Resources Commission (NRC) meeting last year when they directed the MDNR Wildlife Division to arrange a CWD Symposium with other states to share knowledge and information in regards to CWD, for this fall, and I truly commend the NRC for taking this action. I also commend the MDNR Wildlife Division for arranging the very well run CWD Symposium at the Kellogg Center in Lansing in early October, which I attended. There was a very impressive list of experts (most had a PhD at the end of their names) from several states affected by CWD as well as the USDA, the captive service industry and there was even a representative from Norway.
It was an amazing podium of speakers to say the least, and I was in for a whole new world of enlightenment in regards to CWD. Normally I’m not the sort who can sit all day long in a stadium seat without getting a bit antsy. However I was riveted to my seat and anticipating what each new speaker had to say. Not incredibly at all, those two days of sitting stationary on my behind whisked right by. At the end of each day, the experts formed a panel to answer any and all questions, which there were a lot of, and good ones too.
Certain issues were brought to the forefront, and one was in regards to the fact that whitetail bucks are more likely to transmit CWD than female deer. This is because female deer tend to remain as a family clan (mothers, daughters and sisters) in a smaller territory and males disperse from the family clan when they are 1 ½ years old (I’ve read the females give the yearling males in their group “the boot” which in turn prevents inbreeding). Dispersed males can go as far as several miles before establishing a territory, and they are known to wander even farther during the rut.
Missouri for instance, established mandatory antler point restrictions (APRs) from 2004 until 2012, but dropped the mandatory APRs in order to prevent the spread of CWD, because mature bucks tend to be the major carriers of CWD in a deer herd. Missouri looks upon dropping the mandatory APRs as being a reasonable management practice to eliminate CWD, and noted that the annual deer-kill ratio didn’t drop any, with a lot of yearling (1 ½ year old) bucks being harvested, because Missouri deer hunters obviously love to hunt deer. Dropping the mandatory APRs very apparently didn’t cause much hunter dissatisfaction.
Pennsylvania (which discovered CWD in 2012) on the other hand is not dropping its mandatory APRs and needs to see more evidence before doing so.
Michigan has a combo-buck tagging system which entails one non-restricted buck tag and one restricted buck tag (requiring 4 points on one side). In what is determined as the CWD Zone, the restricted buck tag is now considered as being non-restricted and the buck tags can also be used for antlerless deer (see the 2017 Hunting Guide for details and a map of the CWD Zone). The key here is to obtain more samples over a broader spectrum and to lower what are considered as being a high number of deer in the affected zone.
On another side of the issue, I’m also aware there are folks, some quite notable, who believe CWD has always been a natural occurrence in North American deer and look upon the measures being taken by government officials as being too drastic and uncalled for, and as a result is dramatically harming the future of deer hunting.
The impressive panel of experts I observed during the CWD Symposium from several states, the USDA and even Norway all agreed that CWD has all the hallmarks of being a new disease clearly involving prions, that should be taken very seriously and requiring a positive response. There have been no confirmed cases of CWD crossing over the species barrier to humans who have eaten venison from CWD infected deer (which often appear very healthy), but health organizations recommend to not eat any venison from a deer that has tested positive for CWD.
As the incident of BSE (mad cow disease) in the United Kingdom makes very clear, anything is possible and there is a whole lot to yet be learned about CWD.