The illness, which is actually called chronic wasting disease, affects free-ranging deer, elk, and moose.

It may sound like a scene out of a horror movie, but cases of "zombie deer disease" are popping up across the Midwest and some experts are warning it could pose a threat to humans.

The illness, which is actually called chronic wasting disease, affects free-ranging deer, elk, and moose. The disease erodes the brain so the animal salivates and acts lethargic, in a sort of zombie-like state.

The Centers for Disease Control and Prevention says cases of chronic wasting disease have been reported at least 24 states, as well as two provinces in Canada.

The disease is always fatal. It is thought to spread between animals through contact with contaminated body fluids and tissue. It can also be transmitted indirectly through environmental exposures, such as in tainted drinking water or food.

"It's a disease that you can't get rid of," Dale Garner, wildlife chief for Iowa's Division of Natural Resources, told CBS Chicago. "There's no cure so far. So as long as you have deer on the landscape, and it continues to spread from animal to animal, you'll probably have more."

To date, there have been no cases of chronic wasting disease, or CWD, in humans. However, some experts have raised concerns that it could pose a threat to people.

Michael Osterholm, the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, recently warned that the nature of the disease is similar to mad cow disease, which can be transmitted from infected cows to people.

"It is my best professional judgment based on my public health experience… that it is probable that human cases of CWD associated with the consumption of contaminated meat will be documented in the years ahead. It is possible that number of human cases will be substantial and will not be isolated events," he said, according to the Twin Cities Pioneer Press.

Like mad cow and Creutzfeldt-Jacob disease in humans, chronic wasting disease is believed to be caused by abnormal proteins called prions which multiply and cause damage to the brain and spinal cord.