explainer
Cases of chronic wasting disease in Yellowstone National Park raise concerns about human transmission.
In what scientists call a “slow-moving disaster,” “zombie deer disease” has spread across the United States since cases were discovered in Yellowstone National Park.
The deadly disease has no cure and is prevalent in deer and elk, but research suggests it can also spread to humans.
Here’s what we know about this disease and whether people should worry.
What is zombie deer disease?
According to the Centers for Disease Control and Prevention (CDC), the U.S. national health agency, zombie deer is a chronic wasting disease (CWD) that first occurs in deer, elk, reindeer, sika deer, and elk. It is unclear how the name “zombie deer” came about.
It damages the animals’ brains, causing dementia-like symptoms and eventually death. There is no treatment or vaccine.
CWD is spread by prions, a group of proteins that are nearly indestructible and affect both animals and humans. These cause a type of rare progressive neurodegenerative disease. That is, it affects the nervous system and gradually worsens.
The World Health Organization is calling for known prion disease agents, such as animals infected with zombie deer disease, to be kept from entering the human food chain. However, there is no strong evidence that humans can be infected with CWD prions from animals.
What are the symptoms of zombie deer disease?
The prions in this disease cause cells in the brain and spinal cord to fold abnormally and clump together.
About a year after infection, animals begin to show symptoms such as dementia, unsteadiness, drooling, aggression, and weight loss.
Where was the zombie deer disease detected?
The National Park Service announced in mid-November that a deer carcass in Yellowstone National Park tested positive for the disease.
The CDC also reported that “as of November 2023, CWD has been reported in free-ranging deer, elk, and elk in at least 31 states in the continental United States and three Canadian provinces.”
Cases have also been reported in Norway, Finland, Sweden and South Korea.
However, the first-ever case of zombie deer disease was first discovered in Colorado in 1967, according to the U.S. Geological Survey.
Chronic wasting disease has been confirmed in a Yellowstone National Park mule deer found near Yellowstone Lake.
To avoid bringing CWD home, we all need to take additional steps on the ground to be part of the solution. If you would like to learn more please visit: https://t.co/iHGnrGPmFn pic.twitter.com/5MGtElizlk
— TRCP (@TheTRCP) November 20, 2023
What is the risk of zombie deer disease spreading to humans?
So far, there have been no reports of zombie deer disease being transmitted to humans.
However, experimental studies on CWD suggest that it is possible, especially when humans eat infected meat. Currently, the CDC estimates that up to 15,000 CWD-infected animals are eaten each year.
Additionally, the temperatures required to cook prions in meat are far above normal cooking temperatures.
In animals, it is transmitted through saliva, urine, blood, or feces. Prions can also persist in the environment for long periods of time, according to the CDC.
Has a disease ever spread from animals to humans?
It’s pretty common. In the 1980s and 1990s, it was discovered that mad cow disease was transmitted from animals to humans in the UK. A total of 232 people have died from the disease worldwide, according to the U.S.-based Food and Drug Administration.
Zoonotic diseases that can spread from animals to humans, from rabies to avian influenza, have long been a major public health challenge, with humans increasingly invading the natural habitats of various animal species. As they infiltrate, the problem is getting worse.
The world’s most devastating pandemic in 100 years, COVID-19, is widely believed to have jumped from animals to humans at a wet market in the Chinese city of Wuhan. Within four years, nearly 7 million people around the world have died from COVID-19.
What precautions can people take against zombie deer disease?
The CDC lists several precautions against eating meat infected with CWD.
- Test the animals you hunt before eating the meat.
- Avoid “deer or elk that appear sick, acting strangely, or are found dead.”
- Use latex or rubber gloves when removing the entrails of a hunted deer, minimizing contact with the brain and spinal cord tissue.
- Do not use household knives or cooking utensils when handling venison.
Determining whether a deer is infected can only be done after the deer has been killed, as the test requires deep tissue samples from the brain.