Zombie deer disease, also known as chronic wasting disease (CWD), is a fatal brain disorder that affects deer, elk, moose, caribou and reindeer. It is caused by abnormal proteins called prions that damage the nervous system and cause weight loss, drooling, stumbling, listlessness and a blank stare. The disease has been found in 800 samples of deer, elk and moose across Wyoming, according to media reports¹². However, experts are worried that this is a slow-moving disaster and is likely to spread to humans as well. It is fatal, with no known treatments or vaccines.
Brown and white deer on green leafed grass during daytime Credit: UnsplashCWD was first detected in Colorado in the 1960s and has since spread to 26 states in the US, as well as Canada, Norway and South Korea. It is highly contagious and can be transmitted through direct contact, saliva, urine, feces, blood, carcasses and environmental contamination. It can also cross species barriers and infect other animals, such as monkeys and mice.
The disease has recently reached Yellowstone National Park, the most famous nature reserve in the US, where it poses a threat to the ecosystem and the wildlife tourism industry. The park is home to the largest and most diverse array of large wild mammals in the continental US, including bison, wolves, bears, cougars and more than 10,000 elk². The discovery of CWD in a deer carcass in the Wyoming area of the park has raised concerns that the disease may someday spread to humans who visit or live near the park.
"There is a real possibility that CWD could jump the species barrier and infect humans," said Dr. Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota. He cited the example of mad cow disease, a similar prion disease that originated in cattle and infected more than 200 people in the UK and Europe in the 1990s and 2000s, causing a fatal brain condition called variant Creutzfeldt-Jakob disease (vCJD).
Osterholm warned that CWD could have a long incubation period in humans, meaning that symptoms may not appear for years or decades after exposure. He also said that current diagnostic tests may not be able to detect CWD in humans, and that there is no surveillance system in place to monitor the potential risk. He urged the public health authorities and the wildlife agencies to collaborate and take preventive measures to reduce the spread of CWD and protect human health.
Some of the measures that have been suggested include banning the feeding and baiting of deer, testing and disposing of infected animals, restricting the movement of deer and deer products, educating hunters and consumers about the risks of CWD, and developing new methods to detect and treat the disease.
However, some experts say that these measures may not be enough to stop the epidemic, and that more research is needed to understand the nature and extent of CWD and its potential impact on humans and animals. They also say that the public should be aware of the signs and symptoms of CWD and avoid contact with sick or dead deer and their products.
"CWD is a serious and emerging threat to wildlife and human health," said Dr. Cory Anderson, a wildlife veterinarian and researcher at the University of Wyoming. "We're dealing with a disease that is invariably fatal, incurable and highly contagious, with no easy way to eradicate it. We need to act now before it's too late."