ST. PAUL, Minn. – Animal-health officials confirmed Minnesota’s first case of chronic wasting disease on Friday, marking the spread of the incurable illness into a 10th state.

The state Board of Animal Health said a farm-raised elk tested positive after dying mysteriously. The rest of the Aitkin County herd has been quarantined.

Officials said they didn’t know the source of the infection. They didn’t say how many animals were in the herd.

Chronic wasting disease destroys the brain in deer, elk, moose and caribou and causes the animal to grow thin and die. Once found just in a small area of Colorado and Wyoming, the illness has spread through elk ranches and wild deer and elk herds as far away as Wisconsin.

In efforts to contain the disease, thousands of captive elk have been slaughtered in Colorado and hundreds of deer have been killed in Wisconsin. The disease has also been found in New Mexico, South Dakota, Nebraska, Montana, Kansas, Oklahoma and Canada.

On Wednesday, Wisconsin Gov. Scott McCallum told federal officials that a third of hunters could skip this season over fears about the safety of deer meat, jeopardizing his state’s battle to control the disease.

McCallum sent a letter to U.S. Agriculture Secretary Ann Veneman urging her agency to “get off the dime” and approve a rapid test for the disease and certify private laboratories so they can also do testing.