A Kansas man may have died of Creutzfeldt-Jakob, a rare disease that turns brain tissue spongy, health officials said.

The disease also affects the central nervous system.

Health officials said they did not know when or how the Kansas man got the disease, citing its incubation period of years. It also will not be known until testing is complete in several weeks what form of disease he carried.

The 53-year-old Colby man, whose identity was not released, died Friday at Wesley Medical Center, where he had been a patient since December.

Wesley spokesman Paul Petitte said the diagnosis for now is Creutzfeldt-Jakob disease, or CJD. That can be confirmed only through the testing of brain tissue, which will be done through the National Prion Disease Pathology Surveillance Center.

Kansas has an average of three CJD cases a year, said Joe Blubaugh, spokesman for the state Department of Health and Environment.

One form of the disease, called variant Creutzfeldt-Jakob, is related to mad cow disease, or bovine spongiform encephalopathy, and may come from eating infected beef or from blood transfusions. The human form of mad cow disease has never been seen in the United States in someone not exposed in another country.

Most cases of classic Creutzfeldt-Jakob occur spontaneously, according to the Centers for Disease Control and Prevention. In rare cases, it also can be hereditary.

Nationwide, one to two people per million have a spontaneous case of CJD each year, according to the CDC. Between 250 and 300 cases of CJD are reported each year.

“We have no idea of how he possibly contracted this,” said attending physician Richard Liepins.

The man worked in a meatpacking plant “quite a few years ago,” Liepins said. He was also an elk hunter.

Chronic wasting disease, found in some deer and elk, is another form of spongiform encephalopathy. It is known to spread from animal to animal, but so far there’s no concrete evidence that it can be transmitted to humans.