A Breakthrough for Chronic Wasting Disease? (2024)

A new paper published in the journal PLoS ONE

finds household bleach can deactivate Chronic Wasting Disease prions.

But what does that really mean?

Last week, I traveled to Colorado to go fly fishing and photograph wildlife. I covered a lot of ground, from South Fork to Estes Park. Along the way, dozens of mule deer, whitetails and elk posed for my camera. Each time I clicked the shutter, I wondered, “Does this animal have chronic wasting disease”?

Colorado was the first place this highly contagious, always fatal disease was first discovered in the United States in the 1960’s. As of last July, Colorado Parks and Wildlife reported CWD in 31 of its 54 deer herds, 16 of its 43 elk herds and 2 of its 9 moose herds. Colorado is now just one of 26 states with CWD.

CWD is a transmittable spongiform encephalopathy (TSE), an abnormally folded protein that’s more commonly called a prion.

It’s similar to what causes mad cow disease in cattle and scrapie in sheep. The national Center for Disease Control (CDC) warns us to avoid exposure to it. So far, there are no confirmed cases of CWD in humans, but mad cow disease has jumped the species barrier in the form of Creutzfeldt-Jakob disease, caused by eating contaminated beef products. Hence the warning.

Unfortunately, once CWD comes to an area, it’s impossible to get rid of it. Sick animals shed prions into the environment primarily through saliva, urine and feces. Those prions exist for years on plants and in the soil, where other animals pick them up. There has been no way to stop the spread. But a new paper may offer a starting point.

A Breakthrough for Chronic Wasting Disease? (1)

The News

A new paper in the journal PLoS ONE, “Inactivation of chronic wasting disease prions using sodium hypochlorite”, by Katie Williams, Andrew Hughson, Bruce Chesebro and Brent Race, may offer a bit of hope as researchers try to stop the disease.

Sodium hypochlorite is basically household bleach. The title offers a bit of hope in what is a depressing wildlife situation. Could household bleach be a cure? Well, not quite.

I had spoken to one of the authors of the paper, Brent Race, a staff scientist at the Laboratory of Persistent Viral Diseases at the National Institute of Allergy and Infectious Diseases (NIAID) for my previous Cool Green Science blog on CWD in February. I immediately called him again.

“Does bleach kill CWD?” I asked Race excitedly.

“Technically, you can’t kill CWD because prions aren’t alive, but it does inactivate them in certain situations,” replied Race. “We’ve known for decades that bleach is effective on other prions, like the type that causes mad cow disease. We needed a way to decontaminate our equipment. We thought bleach would work on CWD, too, but it wasn’t tested.”

A Breakthrough for Chronic Wasting Disease? (2)

The Experiment

To see if their hunch proved true, the research team followed a three-step process. Step 1 looked at the effect of bleach on a slurry of brain matter infected with CWD.

“We started with this step to quantitate how many prions bleach would eliminate,” said Race. “It significantly decreased prion seeding… Seeding activity correlates to infectivity. Abnormal prions self-replicate through a biochemical interaction with normal prion-proteins.”

Step 2 determined whether bleach would inactivate CWD prions on nonporous surfaces, like stainless steel countertops and knives. The team dropped strips of large-gauge surgical suture wire into test wells with different concentrations of bleach and water. It worked. However, it took a high concentration of bleach (40 percent) and the metal needed to be submerged for five minutes.

“We were hopeful that a lower concentration of bleach would work, and in less time,” said Race. “That’s a lot of bleach, but it matches historical papers on the use of bleach to deactivate prions.”

Step 3 looked at the effects of bleach on solid pieces of infected tissue. Unfortunately, it had no effect, which was no surprise.

“Bleach doesn’t penetrate tissue well. Most chemicals don’t, except formaldehyde,” explained Race. “We knew that going into the experiment… Bleach is only good as a surface disinfectant. It won’t ever be useful to inactivate CWD in the environment. It gets quenched by soils and other organic matter. It’s only a method for decontaminating equipment.”

As such, the research is primarily of value to field biologists and agency staff dealing with lots of animals. Still, such research can be vital as conservationists rush to understand this rapidly spreading disease.

A Breakthrough for Chronic Wasting Disease? (3)

Using Bleach at Home

Outside of a lab, the most practical application of the team’s findings is cleaning knives, meat processing equipment or other metal objects that come in contact with CWD infected meat. If you do, Race offers these four tips:

  1. Don’t overdo it:Use a 50-50 solution of water to bleach because it’s easy to measure. More bleach is not better.
  2. Keep an eye on it: If you notice a color-shift or any other change in the object, remove it from the bleach solution. Bleach can be highly corrosive to certain metals.
  3. Watch the time:Don’t throw your heirloom knife into the bleach solution and come back in two hours. The prions inactivate in five minutes. Much longer, and the bleach might damage the item.
  4. Ventilate the area:Bleach fumes can burn your lungs or cause other respiratory problems in enclosed areas.

Race also warns that all visible chunks of tissue must be removed before depositing an item in the bleach-water mixture, as the bleach won’t penetrate the tissue.

What if you don’t get it all of the tissue off the item you’re trying to decontaminate? Getting most of it is better than nothing.

“A prion can only multiply when it encounters another prion. They need the building blocks, tissue,” explained Race. “They aren’t dangerous on a knife, but that knife can transfer them to a piece of meat where they could amplify. The same is true in the environment. They won’t increase on their own. They need to be inside a susceptible animal, sniffed up a deer’s nose or eaten with a piece of grass.”

A Breakthrough for Chronic Wasting Disease? (4)

The Implications

Bleach isn’t the cure-all for CWD. It only works on nonporous surfaces, but it’s the first thing scientists have discovered that inactivates the abnormal prion that’s wreaking havoc on cervid herds. What’s more, we know the concentration and exposure time for bleach to be effective. And it works any time, today or in three weeks, because, unfortunately, the prions don’t disappear.

“We did the study to provide the science,” says Race, “We’re not making an official recommendation, but we’re hoping that the CDC will comment officially as a result. Now at least I can say ‘this does work’.”

Join the Discussion


  1. Thanks for the update on CWD research, Lisa. Another excellent article from one of the country’s top outdoor communicators!

  2. Household bleach has a concentration of 3-8%. The required concentration was 40% for 5 minutes according the research. Household bleach is likely to do nothing more than ruin the edge on a knife that likely should have been disposed of as a hazmat and encourage its continued use. With the consequences being exposure to a potential brain destroying pathogen, not making the distinction would appear to be exceedingly irresponsible.


  3. Since bleach & vinegar have about the same success rate in disinfecting, with vinegar having much less adverse effects, I wonder if it would be effective is this situation. Just a thought.


  4. Well put Lisa, thanks…

    FRIDAY, NOVEMBER 08, 2019

    ***> EFSA Panel on Biological Hazards (BIOHAZ) Update on chronic wasting disease (CWD) III



  5. Wow. Never realized we could come close to finding something that can stop this.

    When I first read about CWD I said, this is a tough one. This can survive on plants and in soils for years until an unsuspecting animal comes along and eats it or breathes it in. This can happen anywhere and everywhere. This is out in the wild and can be extremely difficult to locate, chase down and take a stand against.

    My feeling is to find something that can definitely minimize it in one or more situations is totally amazing.


  6. Good info, Lisa. Thanks!


  7. Ventilate the area really should be step 1 and they also forgot another important step: rinse the bleached item in clean water thoroughly and dry completely to stop any corrosion!


    1. Thanks, Mary. Good point. I figured that was obvious, but good to mention.

  8. Well, maybe this bit of new info will encourage more research – possibly coming up with a solution that WILL kill this disease. Seems to me with the wildlife agencies still bringing wild elk into “feeding grounds” that hasnt helped the situation, nor have the deer “farms” – where, from what I’ve read, the disease really got its start!
    Good article.


A Breakthrough for Chronic Wasting Disease? (2024)


Is there a cure for chronic wasting disease? ›

Prions change normal proteins in the host animal's cells resulting in concentrations of abnormal proteins. Over time, these abnormal proteins accumulate in the central nervous and lymphatic systems causing a degenerative lack of control and a “wasting-away” death. There is no known cure or vaccine for CWD.

Can humans eat deer with CWD? ›

Hunters should avoid eating meat from deer and elk that look sick or test positive for CWD. They should wear gloves when field-dressing carcasses, bone-out the meat from the animal, and minimize handling of brain and spinal cord tissues.

Can CWD be stopped? ›

What is the treatment for chronic wasting disease? CWD is fatal to animals and there are no treatments or vaccines.

What states have confirmed CWD? ›

Since 1997, CWD has been found in farmed cervids (white-tailed deer, red deer, and elk) in 16 States: Colorado, Kansas, Michigan, Minnesota, Missouri, Montana, New York, Oklahoma, South Dakota, Iowa, Nebraska, Ohio, Pennsylvania, Texas, Utah and Wisconsin.

Has anyone ever got CWD? ›

No CWD infections in people have ever been reported. And it's not known if people can even get infected with CWD. However, CWD is related to another prion disease in animals that does infect people. So, it is considered a theoretical risk to people.

Can you survive chronic wasting disease? ›

Chronic wasting disease (CWD) is a fatal nervous system disease that impacts cervid (deer family) mammals. In deer, it has a 100% mortality rate. What causes CWD? The prevailing theory is that an infectious protein called a CWD prion causes other brain proteins to change to a diseased form.

What is the human equivalent of CWD? ›

CWD is related to other mammalian transmissible spongiform encephalopathies (TSEs), such as Creutzfeldt-Jakob disease (CJD) in humans, bovine spongiform encephalopathy (BSE) in cattle, and scrapie in sheep.

How do you destroy CWD? ›

Chronic wasting disease prions are the Chuck Norris of infectious materials. Incinerating them at 1,112°F will only slightly degrade their infectivity, and you must hit 1,800°F to destroy them. They are just fine left out in the environment for years, outside an animal host, without losing infectious potential.

Does cooking get rid of CWD? ›

Can I cook CWD out of my deer meat? No. Unlike bacteria and parasites that can be killed through the cooking process, CWD prions cannot be cooked hot enough at home to make them un-infectious.

Can meat be tested for CWD? ›

CDFW cannot test “meat” for CWD. While it is possible to test for and detect CWD prions in meat and other tissues, these tests are currently only available in specialized research labs and not for diagnostic or consumer use.

Is chronic wasting disease getting worse? ›

Experts are alarmed about the rapid spread of CWD in deer. Recent research shows that the barrier to a spillover into humans is less formidable than previously believed and that the prions causing the disease may be evolving to become more able to infect humans. A response to the threat is ramping up.

Has a deer ever died from CWD? ›

Chronic wasting disease kills an animal 18 to 24 months after it contracts the disease, according to most experts. Chronic wasting disease is caused by a misfolded protein, or prion, and is fatal to deer, elk and moose, according to the prevailing theory.

Why do humans not get CWD? ›

CWD has not been shown to be infective to humans. Current research indicates that there is a robust species barrier that keeps CWD from being readily transmitted to humans. In fact, there are several other species that don't seem to contract CWD either, like cattle and pronghorn.

Is CWD evolving? ›

Experts are alarmed about the rapid spread of CWD in deer. Recent research shows that the barrier to a spillover into humans is less formidable than previously believed and that the prions causing the disease may be evolving to become more able to infect humans.

Is there a vaccine for CWD? ›

CWD is the only prion disease occurring both in wild and farmed animals, which, together with extensive shedding of infectivity into the environment, impedes containment strategies. There is currently a strong push to develop vaccines against CWD, including ones that can be used in wildlife.

Do deer recover from CWD? ›

Problems develop in the deer's brain because the abnormal proteins accumulate to the point they disrupt nervous-system function. Deer so afflicted lose coordination, become listless, lose body weight, and eventually die. That CWD is always fatal to deer is well established.


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