Two deer in southern Ste. Genevieve County recently were discovered to be positive carriers of chronic wasting disease, a neurological disease that causes degeneration of brain tissue.

The Missouri Department of Conservation has reported CWD-positive results for 15 free-ranging deer out of nearly 18,400 test results this season.

The Ste. Genevieve County cases mark the southernmost reports of CWD-infected deer in the state.

Wildlife regional supervisor for the MDC Matt Bowyer said the prion disease is fatal and will kill any deer it infects. No known cure or vaccine for the disease exists.

CWD is similar to bovine spongiform encephalopathy, commonly called mad cow disease. Both prion diseases cause neurodegeneration to the animals they infect. Human consumption of BSE-infected flesh, however, can be fatal as its transmission causes Creutzfeldt-Jakob disease.

While Bowyer said the MDC does not recommend consuming CWD-infected flesh, he added it can take several months for an infected deer to begin showing symptoms of the disease. During that time, a hunter may not be able to determine whether a deer has been infected.

The Centers for Disease Control and Prevention reports no cases to date of CWD infection in humans, but studies show non-human primates may be at risk for transmission of the disease. These studies, Bowyer said, raise concerns humans also may be at risk.

"There's still a lot of work to be done to try to figure out how transmissible it could be, you know, the potential for infection out there," Bowyer said. "All this stuff is really recent, so we're still trying to figure out how to handle that."

Symptoms include drastic weight loss (or wasting), stumbling, listlessness or other neurological symptoms, according to the CDC's website.

Bowyer said it is transmitted from deer to deer through contact or saliva, and adult males are the main culprits.

"If [CWD is] in a population, theoretically, it's going to eventually wipe out that population over time," Bowyer said.

The MDC does mandatory sampling each season to track the spread of the disease across the state. The department reported again this year no new cases of the disease in central Missouri, noting the low number of CWD-positive cases in new counties such as Cedar, Polk and Ste. Genevieve suggest recent disease introduction to those areas.

When a CWD-positive test result is found, Bowyer said the MDC begins to sample intensely around where the positive result was found. If the department finds more positives in that same area, Bowyer said the department then tries to tighten the sampling area and eradicate the disease by lowering the population of deer in that area.

While the disease raises possible food safety concerns as well as concerns about the deer population in Missouri counties, Bowyer said it's important to remember how small a number there are of CWD-positive cases.

"It's a very small percentage," Bowyer said. "Obviously, if I shot a deer that was in a county that had known positives for CWD, I'd probably get samples, as well."

The 15 new cases of CWD bring the total number of positive cases in the state to 57. MDC will continue sampling hunter-harvested deer, roadkill, sick deer and more and share final testing results in April.

"For right now, it's a high priority for us as an agency. We're trying to do everything we can to slow the movement of this disease, monitor the movement and continue to try to do what's best for our deer herd and for people in Missouri," Bowyer said.