When wildlife disease coordinator Shane Hesting starts talking next week about chronic wasting disease, he'll be sure to mention the continued focus on deer in a 12-county area of northwest Kansas.

And he'll tell the Kansas Wildlife and Parks Commission, meeting Thursday in Goodland, about the sharp increase in CWD-infected cases found last year during a similar sampling period.

As it turns out, the state-run sampling program -- extended in northwest Kansas to obtain extra samples -- found 15 infected deer last year.

Four of those positive tests for the always-fatal brain-wasting disease came after the normal sampling period and all of them from Decatur County -- the virtual epicenter of the CWD epidemic in Kansas. All told, nine Decatur County deer last year tested positive.

While it's possible to determine the infection rate, Hesting said counts currently are under way.

"I'd say it's 4 percent or higher," he said of the infection rate in Decatur County. "That's conservative. I'd say it's higher than that."

How much higher is uncertain.

Positive samples also came from Rawlins, where two were found, and one each from Thomas, Sheridan, Graham and Logan.

Since the first free-ranging case of CWD was found in Kansas in Cheyenne County in 2005, the state's testing program has found a total of 29 cases of CWD. All of them have been in white-tailed deer.

More than half of those, 17 in all, have been found in Decatur County.

This year, the Kansas Department of Wildlife and Parks has enough money to pay for about 2,900 tests.

Northwest Kansas will be the focus of those tests.

"That's where it is," Hesting said of the disease. "We get what we can there."

So much so that he's all but opened up the sampling process in the 12-county area that includes Cheyenne, Rawlins, Decatur, Norton, Sherman, Thomas, Sheridan, Graham, Wallace, Logan, Gove and Trego counties.

In that area, he wants samples from all road-killed and sick or suspect deer, as well as yearlings and older deer that are killed by hunters.

Elsewhere, he only wants samples from deer that are at least 21βΡ2 years old or older.

Generally, CWD is a disease of older deer, with symptoms generally not becoming visible until a deer is more than 2 years old.

But, younger deer can become infected and show symptoms when they are only nine months old.

"They shed the prions at four months without any symptoms," he said.

The prions, misshaped proteins, are responsible for the disease and can be spread between animals.

Hesting is hoping to get 500 samples from the northwest, a threshold for testing accuracy.

While he's not certain exactly why Decatur County has been such a hotbed of CWD infections, there's the possibility that a former captive cervid operation in the area might have introduced the disease.

"There were rumors that diseased elk came from Colorado," Hesting said of the Decatur County operation that is no long operating. "I don't know the whole story."

KDWP, however, has been investigating the situation, he said, to determine what might have happened.

But there's also the possibility, Hesting said, that infected deer moved into the area from either Nebraska or Colorado. Nebraska had its first case of CWD in 1999, while the disease was first discovered in Colorado in 1967.

The first infected deer found in Cheyenne County is thought to have come in from Colorado.

The additional cases of CWD found in Decatur County were a result of efforts to supplement the number of samples taken. One was a road-killed animal, while three others were found when deer killed through a depredation permit were tested well after hunting seasons ended.