(NewsNation) — New reports of deer infected with so-called “zombie deer disease” have sparked concerns that the illness could make the jump to humans. Here’s what you need to know.

What is zombie deer disease?

The official name of the illness is chronic wasting disease. It’s a prion disease, a classification of diseases that cause neurodegenerative changes and are almost always fatal.

It became known as zombie deer disease due to the symptoms, which include weight loss, drooling, confusion, listlessness and stumbling.

CWD occurs in deer, moose, elk and caribou.

Where has zombie deer disease been reported?

Cases of CWD have been reported across the U.S. and Canada, with most of the instances clustered in the West and upper Midwest. Smaller clusters have been reported in the mid-Atlantic region and Southwest.

There are 31 cases where CWD has been found, though the Centers for Disease Control and Prevention notes that it could be present but undetected in other states.

How is zombie deer disease spread?

Scientists believe the disease is spread through bodily fluids, including urine, feces, blood and saliva. Transmission may be from direct contact with fluids or indirectly through environmental contamination.

Can zombie deer disease spread to humans?

So far, there’s no indication CWD can infect humans. However, some research suggests that it can infect some primates and could be spread between primates.

Prion diseases have made the jump from animals to humans before, most famously with bovine spongiform encephaly, more commonly known as mad cow disease.

If CWD were to spread to humans, scientists believe the most likely cause would be through eating meat from infected animals.

The CDC advises hunters to avoid eating meat from deer that act strangely or are found dead, such as roadkill, and to wear gloves while dressing the animal. Hunters should also check with state authorities, as some states may strongly recommend or require meat be tested for CWD. The agency also suggests hunters who have meat commercially processed request the animal be processed individually to avoid contamination from other animals.

How dangerous is prion disease?

Prion diseases are different from viruses or bacteria and are caused by agents that induce abnormal folding of cellular proteins called prion proteins found in the brain. That leads to brain damage and neurological degeneration.

Prion diseases progress quickly and are nearly always fatal.

There are several prion diseases known to occur in humans, including Creutzfeldt-Jakob disease, which usually happens spontaneously or may be inherited.

What is being done about it?

The main things being done to prevent the spread of CWD are surveillance of animals and requirements for testing meat. Some states may also limit what meat or animal products may be imported to avoid environmental contamination that could spread the disease.