Texas Parks & Wildlife Magazine   


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Deer Sought for Disease Sampling

TPWD steps up monitoring after discovery of chronic wasting disease.

By Steve Lightfoot

With the recent discovery of chronic wasting disease (CWD) in two captive-deer-breeding facilities in South-Central Texas, the Texas Parks and Wildlife Department will be stepping up efforts to strategically sample hunter-harvested deer at a greater level during the 2015–16 hunting season.

Hunters are encouraged to assist with this statewide monitoring effort by voluntarily submitting samples this fall. TPWD biologists will collect samples and submit them to the Texas A&M Veterinary Diagnostic Lab at no cost to the hunter. Tissue samples from the heads of deer must be collected within 24 hours of harvest (up to 48 hours if kept chilled). It is important that the deer head not be frozen.

Since 2003, TPWD biologists have been monitoring the state’s free-ranging deer population for CWD. Using statistical sampling tables commonly used by animal disease experts, biologists set a sampling goal that would detect the disease with 95 percent confidence if at least one out of every 100 deer was infected. Thus far, biologists have collected nearly 30,000 samples from hunter-harvested deer across eight ecological regions. To date, CWD has not been found in Texas free-ranging white-tailed deer. CWD was first detected in Texas in 2012 in free-ranging mule deer in far West Texas.

The sampling strategy for the 2015–16 hunting season is being refined to target disease risk levels within the state’s 33 unique resource management units (wildlife conservation areas that TPWD uses for deer management decisions). Criteria for establishing risk levels include factors such as deer density, susceptible species importation history and proximity to a CWD-positive site.

Sampling goals will range from 60 to 433 deer for each resource management unit, depending on the assigned risk level. Achieving these goals will result in more than 7,000 samples. TPWD will also specifically target sampling efforts within a five-mile radius around the CWD index facility in Medina County to determine the prevalence and geographic extent of the disease in that specific area.

“In the wake of our increased concern about CWD, we are ramping up our sampling effort statewide,” says Mitch Lockwood, TPWD big game program director. “We will be collecting samples from deer and elk and other cervid species in every county where deer hunting occurs.”

Chronic wasting disease was first recognized in 1967 in captive mule deer in Colorado and has been documented in captive or free-ranging deer in 23 states. CWD among cervids is a progressive, fatal disease that commonly results in altered behavior as a result of microscopic changes made to the brain. An animal may carry the disease for years without any outward indication, but in the latter stages, signs may include listlessness, lowering of the head, weight loss, repetitive walking in set patterns and lack of responsiveness.

To date, there is no evidence that CWD poses a risk to humans or non-cervids, but as a precaution, health organizations recommend that people not consume meat from infected animals.

Hunters wishing to submit samples can go online to find their local TPWD biologists, listed by county at tpwd.texas.gov/biologist. TPWD anticipates test results could take three to four weeks to process.

More information about CWD, including safe carcass handling tips and precautions, can be found online at tpwd.texas.gov/CWD.

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