Chronic Wasting Disease (CWD) has been detected in a buck harvested by a Texas hunter in Medina County west of San Antonio. The one-and-a-half-year-old deer was the first confirmed case in a free-ranging whitetail in the state, prompting officials to deploy a strategy designed to contain and limit the spread of the disease. It’s unclear whether other deer in the herd are affected.

“Although the disease has been discovered in a free-ranging whitetail in this area, we cannot draw any conclusions at this time based on one detection,” said Dr. Bob Dittmar, Texas Parks and Wildlife Department’s (TPWD) wildlife veterinarian, in a news release. “The more effective we are at containing this disease within a limited geographic area, the better it will be for our wildlife resources and all those who enjoy them.”

CWD is a contagious neurological disease that affects elk, moose and deer. The disease is always fatal as it causes a degeneration of the brain similar to mad cow disease. It’s thought that CWD is passed through feces, urine or saliva, but scientists have not yet identified the exact cause. While public health officials recommend to avoid exposure to animals infected with CWD, there is no current evidence it causes harm to humans.

Bandera, Medina and Uvalde counties have been deemed CWD Containment Zones in order to prevent any further cases of the disease. This places restrictions on moving carcasses and captive deer. There will be mandatory CWD testing of all deer harvested by hunters in the three counties. The TPWD will collect samples from the containment zone from roadkills and through its Managed Lands Deer Program, which allows for extended hunting seasons for landowners and lessees who participate.

“This emergency action allows us to contain the threat of this disease spreading any further while we collect more information and gather more data,” said Texas Parks and Wildlife Commission (TPWC) Chairman T. Dan Friedkin. “Not only are these temporary emergency measures necessary and consistent with the state’s planned strategies for CWD management, they are essential for ensuring the protection of the state’s whitetail deer herd and the integrity of our hunting heritage.”

In September 2016, Bandera, Medina and Uvalde counties were established as CWD Surveillance Zones. While the new rules did not require hunters to submit their harvests for sampling in these counties, they were encouraged to generate voluntary samples at check stations throughout hunting season, which is ultimately how the disease was discovered.

The disease was first found in Texas in 2012 in a free-ranging mule deer near the New Mexico-Texas border. Another case was discovered in a mule deer harvested in the Texas Panhandle in 2016. Thirteen cases of CWD were confirmed at a captive whitetail breeding facility in Medina County in July 2016, the same county affected by the latest outbreak. CWD is most prevalent in western states like Wyoming, Colorado, Utah, Nebraska, Kansas and New Mexico. However, several states ranging from the Northeast to Midwest have had prior incidents with CWD in captive populations or have it present in free-ranging deer herds.

If CWD becomes widespread it can have a detrimental impact on deer populations and affect hunting seasons. “With a kind of low level of CWD, you’d basically have to quit harvesting those deer populations,” David Hewitt, director of wildlife research with Texas A&M University’s Caesar Kleberg Wildlife Research Institute, told the San Antonio Express-News. “They could just maintain themselves in South Texas here, but you wouldn’t have any recreational harvest.”