|Transmission of other prion diseases to humans has already occurred and there are an estimated 11 million deer hunters in the United States, so the risk of animal-human spread of chronic wasting disease is real. Above, a white-tailed deer. Photo: U.S. Department of Agriculture/Scott Bauer via Flickr Creative Commons (CC BY 2.0 Deed).
TipSheet: On the Hunt To Know More About Chronic Wasting Disease
By Joseph A. Davis
As deer season winds to a close in many parts of the U.S., environmental journalists may find themselves called on to explain chronic wasting disease, bushwhacking their way between what is known and what is unknown.
CWD is a prion disease — a cousin of so-called mad cow disease. It affects white-tailed deer, mule deer, red deer, elk, caribou, moose and related species. It’s a progressive disease that is always fatal to animals that live long enough.
It has so far been found in 32
states, four Canadian provinces
and some other countries.
It seems to be spreading.
It has so far been found in 32 states, four Canadian provinces and some other countries, in both free-ranging and captive-bred populations. It seems to be spreading.
Does CWD pose a health threat to humans? Honest answer: It’s possible but scientists don’t really know. So far it seems not to have done so.
Why it matters
Transmission of diseases from animals to humans — technically, zoonotic diseases — is common and sometimes disastrous.
Case in point: The COVID-19 pandemic is believed to have originated in bats or other animals before it killed more than 3 million people worldwide.
Meanwhile, transmission of other prion diseases to humans has happened. And deer and elk hunting is quite popular in North America. In the U.S., there are an estimated 11 million deer hunters and 1 million elk hunters.
CWD was first recognized in 1967. People became widely worried about another prion disease in the late 1990s and early 2000s. Known by the nickname “mad cow disease,” its scientific name is bovine spongiform encephalopathy.
During the peak of the epidemic in Europe, some 180,000 animals were affected.
Prion diseases — scientifically named transmissible spongiform encephalopathies — are caused by the misfolding of proteins called prions.
Another example is the disease called scrapie, which affects sheep. It primarily affects neurological tissue and causes neurological symptoms.
It is believed that the outbreak of mad cow disease in Europe and the U.K. was caused by feeding cattle meat and bone meal made from diseased animals. Incidence dropped to almost none in the U.K. after feeding with animal by-products was ended.
An outbreak of mad cow disease
several decades ago was
believed to have been caused
by people eating infected beef.
Mad cow was transmitted to humans, where it’s called Creutzfeldt–Jakob disease. Although CJD originated in several ways, the outbreak several decades ago was believed to have been caused by people eating beef infected with mad cow disease.
This variant of CJD killed 232 people, according to the U.S. Food and Drug Administration. It was always fatal.
This is why the question of transmission of chronic wasting disease from animals to humans is of concern.
The key question is whether eating deer and elk meat harvested by hunters might be a possible avenue of transmission to humans. Proper processing and testing can help lower the odds of this. But not all hunters will take these measures.
Story ideas and questions to ask
- Talk to hunters in your audience area. Ask how concerned they are about CWD. Have they ever seen a deer with CWD? Do they test the animals they harvest? Do they eat them?
- Are there any deer farms in your area? Visit and talk to them. Do they test? Are they certified?
- Talk to deer meat processors in your area. What, if any, precautions do they take related to CWD?
- Is deer meat ever donated to programs for the homeless and hungry in your area? Is it tested?
- Has CWD been identified in animals in your state or locality? What has been the response, by government or private parties?
- Do health officials in your area have any programs or efforts to do surveillance for spillover CWD or similar diseases?
- Talk to neurologists in your area about how they could determine diagnostically the difference between potential human CWD and other neurodegenerative diseases like Alzheimer’s disease.
- National Wildlife Health Center: This subunit of the U.S. Geological Survey scientifically studies all kinds of wildlife diseases and ways to mitigate them.
- U.S. Centers for Disease Control and Prevention: The main federal public health agency, a reliable source of scientific information.
- State wildlife agencies: These agencies set hunting rules. The exact name will vary by state. Find yours with this directory.
- State public health agencies: Find yours with this directory.
- State and local research universities: These will vary according to where you are.
- One Health: A collaborative interdisciplinary program that looks at the human-animal health connection.
- Local and regional hunt clubs: You will find many by Googling “hunt clubs near me.”
- Local deer processors: These are essentially butchering services that cut up and freeze deer meat for hunters.
- State veterinary labs: These are often where samples are sent to test for CWD.
- APHIS: The Animal and Plant Health Inspection Service, within the Agriculture Department, certifies the labs that test for CWD.
- National Center for Emerging and Zoonotic Infectious Diseases: Another agency connected to the CDC.
- CIDRAP: The Center for Infectious Disease Research & Policy at the University of Minnesota has a program that engages experts in studying whether and how CWD might be transmitted from animals to humans.
Joseph A. Davis is a freelance writer/editor in Washington, D.C. who has been writing about the environment since 1976. He writes SEJournal Online's TipSheet, Reporter's Toolbox and Issue Backgrounder, and curates SEJ's weekday news headlines service EJToday and @EJTodayNews. Davis also directs SEJ's Freedom of Information Project and writes the WatchDog opinion column.
* From the weekly news magazine SEJournal Online, Vol. 9, No. 6. Content from each new issue of SEJournal Online is available to the public via the SEJournal Online main page. Subscribe to the e-newsletter here. And see past issues of the SEJournal archived here.