What is ‘zombie deer disease’ and are humans at risk?

Scientists are warning a virus dubbed the “Zombie Deer Disease” could potentially spread to humans after Yellowstone National Park saw its first case last month. Zombie Deer Disease, or Chronic Wasting Disease (CWD), is caused by prions that leave animals drooling, lethargic and emaciated, stumbling with a telltale blank stare, according to the Centers for Disease Control (CDC). The prions, abnormal transmissible pathogens, cause changes in the hosts’ brains and nervous systems.

Zombie Deer Disease can spread through deer, elk, moose, caribou, and reindeer and is fatal with no known treatments or vaccines. Cases have been detected across dozens of states, including Ohio, where white-tailed deer tested positive for the disease in Marion and Wyandot counties earlier this year. The disease can be found all across Wyoming.

Park officials estimate 10-15% of the mule deer that migrate to the southeastern section of Yellowstone in the summer have Zombie Deer Disease. Despite the widespread nature of the disease, the long-term effects on deer, elk, and moose are unknown. The disease also transmits among other animals, leaving them drooling, lethargic, stumbling, and with a blank stare.

Zombie Deer Disease has been found in more than 800 samples of deer, elk, and moose across the state of Wyoming, leaving scientists concerned.

Zombie Deer Disease was first detected in November in Yellowstone National Park. Infected animals get this abnormal protein and it causes them, over a year or two, to develop these holes in their brain so they can not feed themselves, eventually they will die. In 2022, officials confirmed cases in 13 Ohio counties. A deer carcass in Yellowstone National Park tested positive for the highly contagious disease, causing some scientists to sound the alarm about possible risks to humans.

The Bovine Spongiform Encephalopathy (BSE) outbreak in Britain provided an example of how, overnight, things can get crazy when a spillover event happens from, say, livestock to people. There is a potential of something similar occurring. It is not definitely going to happen, but it is important for people to be prepared. It is worrying that there is no known way to eradicate it, neither from the animals it infects nor the environment it contaminates.

No known case of Zombie Deer Disease in humans has ever been recorded. The CDC says the disease could pose a risk to certain non-human primates, like monkeys, that eat meat from infected animals, according to some studies. These studies raise concerns that there may also be a risk to people. Since 1997, the World Health Organization (WHO) has recommended that it is important to keep the agents of all known prion diseases from entering the human food chain.

Zombie Deer Disease should be viewed against a backdrop of dangerous emerging zoonotic pathogens.

But experts have now warned the disease could soon become a ‘slow-moving disaster’ and have urged governments across the globe to prepare for the possibility of Zombie Deer Disease spreading to humans in the future. These pathogens are said to be moving back and forth across species including humans across the entire globe. As for humans, any potential outbreaks could occur due to settlements and agricultural operations delving deeper into environments where animals carrying the disease roam.

This will particularly become a concern in the United States as hunting season gets underway. As a result, the CDC is recommending that harvested game animals be tested for Zombie Deer Disease, while meat from cervids that appear ill should not be consumed. The science of what is needed to help slow the spread of the disease is clear, and has been known for a long time.

Do not feed wildlife in the face of a growing Zombie Deer Disease pandemic. There is a lot at stake for the Yellowstone ecosystem, and a lot at stake for all Americans who enjoy having healthy wildlife on the landscape. Studies have also found wildlife predators such as wolves, cougars, and bears are able to detect sick animals long before humans do. They tend to prey on them and remove the animals with the Zombie Deer Disease from the landscape, and have so far been immune to the disease.

Studies raise concerns that there may also be a risk to people.

However, as per some studies, monkeys face the threat of getting infected by Zombie Deer Disease if they eat infected animal meat or come in contact with the bodily fluids or brains of infected animals. The disease is a fatal and contagious disease illness which affects cervids, which is a group of animals that includes elk, deer, moose, reindeer, and caribou. It is caused by a malformed protein, known as prion, which gets accumulated in the tissues and the brain and causes behavioral and physiological changes, emaciation, and ultimately death.

Zombie Deer Disease gets transmitted by direct animal-to-animal contact and also indirectly by getting in contact with infectious particles which are present in soil, vegetation, or faeces. Animals can also get an infection if their pasture or feed is contaminated by the prions which are carrying it. It may take more than a year for the development of symptoms in the deer.

It generally starts with the deer losing weight drastically, stumbling around, and eventually losing all the energy. At present, there is no cure or vaccine with Zombie Deer Disease.