“Zombie deer” disease, officially called chronic wasting disease, or CWD, has spread into 24 states and two provinces in Canada, and researchers are worried humans could contract it, given certain circumstances.

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The disease is primarily found in free-ranging deer, elk and moose, and has been identified in farmed deer and elk, according to the Centers for Disease Control and Prevention.

The illness is fairly low in free-ranging deer and elk, but in some areas where the disease is more established, infection rates can top 10 percent, the CDC reported, and localized infection rates of 25 percent have also been reported. The numbers are even higher in the captive deer population with rates as high as 79 percent or four out of every five deer in at least one captive herd.

As of January 2019, there were 251 counties in 24 states with reported CWD in free-ranging cervids. This map is based on the best-available information from multiple sources, including state wildlife agencies and the United States Geological Survey.

Credit: Centers for Disease Control and Prevention

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Credit: Centers for Disease Control and Prevention

Chronic wasting disease can take as long as a year after infection before symptoms appear, but when they do, they include drastic weight loss, stumbling, listlessness and other neurologic symptoms.

Researchers are concerned that so-called 'zombie deer' disease could spread to humans through the food supply, although there's been no recorded cases so far.

Credit: Pixabay

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Credit: Pixabay

There have been no recorded human infections, but here's why the CDC is concerned. Studies have suggested that non-human primates, like monkeys, that eat infected meat or come into contact with an infected animal's body fluid, could be at risk. The CDC said the research raises concern there could be a risk to people as well.

Since 1997, the World Health Organization has recommended keeping any meat infected with CWD from the food supply.

With no treatments or vaccines for so-called "Zombie deer" disease, the illness is fatal, although some infected animals may never develop the disease.