PIKEVILLE, KY. (AP) — Brain tissue and glands from Kentucky deer killed during last fall’s hunting season have turned up no evidence of chronic wasting disease.

So far, tests have been completed on 500 of 2,500 deer sampled.

“I don’t expect to find anything,” said Jonathan Day, big game coordinator for the Kentucky Department of Fish and Wildlife Resources. “It’s something so bad you don’t want to find it.”

Chronic wasting disease, which attacks the brain and nerve tissue of infected deer and elk, has invaded 10 states, including Illinois, which borders Kentucky.

Related to mad cow disease, chronic wasting disease causes deer to begin acting strangely and then die.

Scientists believe the fatal disease, first detected in Colorado in 1967, is spread through through saliva and feces. It began to spread through captive herds in the late 1990s, and last year was detected for the first time east of the Mississippi River.

The disease has been found in Illinois, Montana, New Mexico, Oklahoma, South Dakota, Wisconsin, Kansas, Nebraska, Wyoming and Colorado.