(This story was first published in the first quarter 2019 issue of the Louisiana Logger)
One of the first wildlife-related news stories that broke in 2018 was confirmation that a free-ranging white-tailed deer had died of chronic wasting disease (CWD) in Issaquena County, Mississippi.
Given the cultural and economic importance of hunting in the region, this discovery raised considerable concern from the public and sparked many questions about the history and ecology of the disease, recommendations and precautions for hunters, potential impacts of CWD on deer populations, and strategies to minimize risk of further transmission.
In response, people involved in CWD surveillance and management operations worked to increase public awareness about the disease and to engage interested parties in CWD monitoring.
To date, CWD has not been detected in Louisiana, but three additional deer have tested positive for CWD in Mississippi since Oct. 1, 2018, and CWD will likely remain a topic of profound interest to natural resource professionals and sportsmen alike in the New Year.
Experience with other wildlife diseases has demonstrated several proactive measures we can all take to prevent CWD from entering Louisiana and to help with management of CWD in other states.
First, we can learn more about the cause of the disease and how infection occurs.
CWD presents fewer hazards when we take preventative steps, and once we have the facts, we can share them with family, friends, and colleagues to help slow the spread of misinformation.
Next, we can contribute to surveillance efforts by reporting any sick or unhealthy deer to state agencies and by submitting samples from hunter-harvested animals for testing.
Wildlife disease surveillance is key to early detection and can help wildlife biologists identify changes in patterns of disease occurrence over time. Most importantly, we can stay informed of any updates to public policy and act accordingly.
Wildlife regulations can change rapidly and new rules may be unpopular, but they are ultimately designed to reduce the risk of spread and keep both animals and people safe.
CWD Affects Nervous System
As an introduction to the topic, CWD is a disease that affects the nervous systems of white-tailed deer, mule deer, red deer, elk, moose and other cervids. It is one in a group of diseases called the transmissible spongiform encephalopathies, which include scrapie in domestic sheep and goats and bovine spongiform encephalopathy in cattle.
The disease is caused by misfolded proteins (prions) that are replicated by host animals. Prions interrupt and degrade nerve cells and ultimately eliminate basic nervous system functions, always resulting in death of the infected host.
The precise origins of CWD are unknown, but the condition was first detected in 1967 in a research mule deer herd in Colorado. It has now been confirmed in 25 states and two Canadian provinces. Again, CWD has not been detected in Louisiana to date, but cases have been reported in all adjacent states.
Symptoms of CWD include emaciation or generally poor body condition; decreased activity or erratic behavior; wide, low stances and blank expressions; excessive drinking and urination; and salivation and grinding of teeth.
These symptoms appear 16 to 36 months after infection, but because these symptoms are common to many wildlife diseases, a positive diagnosis of CWD requires laboratory testing by a trained professional. CWD is spread among infected animals by direct and indirect contact with saliva, urine, feces or a carcass.
These prion-carrying sources are deposited on the ground and in the soil and can be picked up by other animals during foraging. Reservoirs of prions in the environment (e.g., plants) may also enable transmission.
Though mother-offspring transmission is possible, lateral transmission between two animals is the typical route for infection.
There is no evidence to suggest that CWD can be transmitted to traditional domestic livestock (e.g., cattle, sheep and goats) or humans. However, it is good to be cautious.
Experts advise hunters to harvest only healthy-looking animals. Prions accumulate densely in the brain, eyes, tonsils, spine, spleen and lymph nodes of sick animals, so hunters should also avoid touching or eating these parts. In areas affected by CWD, hunters are advised to bone out carcasses in a way that removes all nervous system tissue and be sure not to cut meat with saws or knives that were used to cut bone.
To prevent exposing other susceptible animals to infected material, officials suggest that hunters should bury the carcass at least 6 feet deep or dispose of them in approved landfills. Whether the animal looks sick or not, hunters can submit a sample of their deer to the Louisiana Department of Wildlife and Fisheries for testing. More information on how and where to submit a sample is available at http://www.wlf.louisiana.gov/hunting/CWD.
Unfortunately, there are no vaccines to prevent infection. Once an animal is infected there are no effective treatments. The best way to prevent the spread of CWD for now is to manage susceptible animal populations. The easiest solutions are to:
• Remove and properly dispose of potentially infected animals.
• Prevent high densities of susceptible animals by continuing to hunt and harvest.
• Minimize places where susceptible animals congregate, such as feeding stations.
By law, there is a moratorium on importation of captive cervids. In addition, carcass importation restrictions updated on Oct. 4 state that no person shall import, transport or possess any cervid carcass or part of a cervid carcass originating outside of Louisiana, including Louisiana lands east of the Mississippi River in East Carroll, Madison and Tensas parishes.
Exceptions include meat that is cut and wrapped; meat that has been boned out; quarters or other portions of meat with no part of the spinal column or head attached, antlers, clean skull plates with antlers, cleaned skulls without tissue attached, capes, tanned hides, finished taxidermy mounts and cleaned cervid teeth.
If you see an animal you think might have CWD, do not attempt to touch, kill or move the animal in any way. Instead, carefully document the animal’s location and any other pertinent details, then immediately contact the nearest game warden or wildlife biologist who will obtain samples from the animal.
You can find a condensed version of the information provided here in LSU AgCenter Fact Sheet No. 3623 along with a time series map of all states and provinces with CWD detections in wild or captive deer at www.lsuagcenter.com. More details and the latest news are available on websites and social media hosted by the region’s state wildlife agencies, the CWD Alliance (http://cwd-info.org/), and the National Cooperative Extension Working Group for CWD Education. My colleagues and I also regularly share information about CWD on the LSU Forestry and Wildlife Extension Facebook Page.
Dr. Long is an Assistant Professor of Wildlife Ecology at Louisiana State University’s School of Renewable Natural Resources. You can contact her by email at firstname.lastname@example.org or phone at 225-578-4940.