By Ashley M. Long / Louisiana Logger
As of early December, Chronic Wasting Disease (CWD), a neurodegenerative disease that affects white-tailed deer, mule deer, red deer, elk, moose and other cervids, has not been detected in Louisiana but remains a cause of concern for many of our state’s hunters for good reason.
CWD is one in a group of diseases called the transmissible spongiform encephalopathies, which include bovine spongiform encephalopathy in cattle (otherwise known as “mad cow disease”) and scrapie in domestic sheep and goats. The disease is caused by misfolded proteins (prions) that are replicated by host animals.
The prions interrupt and degrade nerve cells and ultimately eliminate basic nervous system functions, always resulting in death of the infected host. To date, there are no vaccines to prevent infection, and once an animal is infected, there are no effective treatments.
The origins of CWD are unknown, but the condition was first detected in 1967 in a research herd of mule deer in Colorado. It has now been confirmed in free-ranging populations and at captive facilities in four Canadian provinces and 26 states, including Texas, Arkansas and Mississippi.
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 are common to many wildlife diseases. As such, 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, water) also may enable transmission. Though mother-offspring transmission is possible, lateral transmission between two animals is the typical route for infection, and can occur before symptoms develop.
There is no evidence to suggest CWD can be transmitted to traditional domestic livestock (e.g., cattle, sheep and goats) or humans. However, public health and wildlife officials advise hunters to harvest only healthy-looking animals; to wear latex or rubber gloves while field dressing harvested animals; to bone out carcasses in a way that removes all nervous system tissue; to minimize handling of brain and spinal tissues; to wash hands and disinfect tools with a 50/50 solution of chlorine bleach and water after field dressing is complete; to avoid eating tissues associated with the brain, spinal cord, eyes, tonsils and lymph nodes; to have animals tested before consumption and to avoid consuming meat from any harvested animals that test positive for the disease. To prevent exposing other susceptible animals to infected material, officials suggest hunters should bury carcasses at least 6 feet deep or dispose of them in approved landfills.
Wildlife disease surveillance is key to human safety and early detection and can help wildlife biologists identify changes in patterns of disease occurrence over time.
In fall 2019, the Louisiana Department of Wildlife and Fisheries (LDWF) announced it would coordinate with the Louisiana Animal Disease Diagnostic Laboratory at the LSU School of Veterinary Medicine in Baton Rouge to provide testing services for CWD. Each test costs $37.50.
Hunters can submit samples at one of seven LDWF regional offices in the state. Prior to submission of their samples, hunters should record the GPS location where the deer was harvested, remove the head about 5 inches below the ear (deer heads may be caped with antlers and skull caps removed) and to refrigerate, but not freeze, samples before submitting them for testing. More information can be found at http://www.wlf.louisiana.gov/hunting/CWD.
For now, the best ways to prevent the spread of CWD are to remove and properly dispose of potentially infected animals, to prevent high densities of susceptible animals by continuing to hunt and harvest, and to minimize places where susceptible animals congregate, such as feeding stations.
By law, there is a moratorium on importation of captive cervids to Louisiana. In addition, carcass importation restrictions state 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.
The Louisiana Wildlife and Fisheries Commission also passed a declaration of emergency related to deer urine products for the 2019–2020 deer hunting season. The regulation states: “It is unlawful to use or possess scents or lures that contain natural deer urine or other bodily fluids while taking, attempting to take, attracting or scouting wildlife, except natural deer urine products produced by manufacturers or entities that are actively enrolled and participating in the Archery Trade Association Deer Protection Program, which have been tested using real-time quaking induced (RT-QuIC) and certified that no detectable levels of Chronic Wasting Disease (CWD) are present and are clearly labeled as such.”
Given potential modes of CWD transmission, this rule is intended to minimize introduction of CWD to the state.
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 LDWF, 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. Ashley M. Long is an assistant professor of Wildlife Ecology at Louisiana State University’s School of Renewable Natural Resources. Contact her by email at firstname.lastname@example.org or phone at 225-578-4940.)