Does ‘zombie deer disease’ pose a threat to humans?

A new condition similar to “mad cow disease” is spreading quickly among animals in North America - and scientists fear it could cross over and infect humans.

Chronic wasting disease (CWD) - dubbed “zombie deer disease” - has infected deer, elk and moose across 24 US states and two Canadian provinces.

A red deer farm near Ontario in Canada has had 11 confirmed cases.

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Symptoms of the disease, which starts in the tissues of the brain and spinal cord, include “weight loss, clumsiness, listlessness, excessive thirst and drooling”, says The Daily Beast.

Animals “often exhibit bursts of aggression before collapsing and, eventually, dying”, the news site adds.

CWD currently “appears limited to deer, moose, and elk”, says Popular Science magazine. But University of Minnesota researchers warned local lawmakers last week that they need to take immediate action to prevent the potential spread to humans.

Michael Osterholm, director of the university’s Center for Infectious Disease Research and Prevention, compared the situation to the epidemic of bovine spongiform encephalopathy (BSE), or mad cow disease, that hit the UK in the 1990s, when there was initial uncertainty over whether the lethal condition could spread to humans.

At least 156 people in Britain died after contracting BSE, which like CWD is a so-called prion disease, known as transmissible spongiform encephalopathies.

Osterholm said: “It is my best professional judgement 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.”

Up to 15,000 infected animals are eaten each year, a number that could rise by 20% annually, he added.

Scientists “can’t say for sure that CWD will cross over and infect humans”, says USA Today. But according to Osterholm, as time goes on and more infected meat is consumed, the likelihood increases.

Although there is still no concrete evidence that the disease can cross the species boundary into humans, the World Health Organization believes it is possible.

“It's like a throw at the genetic roulette table,” Osterholm said. “If Stephen King could write an infectious disease novel, he’d write it about prions.”

Researchers are hoping to develop an affordable new test that hunters can use to see if the meat of the animals they kill is infected.

In the meantime, “if you hunt (or eat meat that others have hunted for) in one of the infected areas, the US Centers for Disease Control doesn’t necessarily say you can’t eat your venison”, says Popular Science.

But the experts do recommend exercising caution with any animals that look sick or are acting strangely, and to minimise touching the organs as much as possible, especially the brain and spinal cord.