Mad Cow Disease Can Go Airborne? Yes, but Don't Panic

By Eliza Strickland | January 14, 2011 3:43 pm

It sounds like the start of a science fiction movie: a lethal brain disease that goes airborne. But while scientists have indeed found that the prions responsible for mad cow disease and other neurological ailments can float on the breeze and infect those who inhale, they say there’s no reason to barricade your gas-masked family inside your house.

Prions are misfolded proteins that cause brain degeneration; in mad cow disease they’ve typically been transmitted when one cow eats the infected brain or spinal cord tissue of another (something that agricultural institutions now agree shouldn’t happen in the first place). Other prion diseases, including the human variant Creutzfeldt-Jakob disease, are also passed along through body fluids and tissue. But for a new study published in PLoS Pathogens, researchers decided to find out if airborne prions could serve as infectious agents.

The short answer: Yes.

Researchers sprayed an aerosol containing as little as 2.5 per cent infected brain tissue into a chamber containing healthy mice, and found that all of the exposed mice sickened and died of the prion disease scrapie within six months. The mice that spent the most time in the chamber (the exposure times ranged from 1 to 10 minutes) showed signs of the disease soonest. Study coauthor Adriano Aguzzi says it was a startling result:

“Common knowledge is that prions aren’t airborne, and can’t cause infection that way…. We were totally surprised and also a bit frightened at how efficient [airborne infections] were.” [Wired]

Aguzzi believes the prions moved through the nostrils’ olfactory nerves straight to the brain–and some may sneak in through the eye’s optic nerves as well.

Does this still sound terrifying? Well don’t fret, because prions don’t usually exist in an aerosolized form, and therefore you’re extremely unlikely to wander into a cloud of deadly peril. Only a few people have to worry about this: slaughterhouse workers and prion researchers. Wired reports that slaughterhouse workers who remove brains or spinal chords with bone saws may create airborne prions, and New Scientist describes the threat to research and diagnostic labs:

Labs that test for prions routinely make 10 per cent suspensions of brain tissue, and any handling – pipetting, for example – creates aerosols. Prion labs are not required to use safety equipment that protects workers from aerosols. Aguzzi, who tested his aerosols at the highest level of protection, thinks those labs may now need to rethink safety measures. [New Scientist]

Related Content:
80beats: When Prions Do Good: Properly Folded Proteins May Protect Nerve Cells
80beats: Who Needs DNA? Prions Evolve Without It
80beats: New Guinean Cannibals Evolved Resistance To Mad Cow-Like Disease

Image: PLoS Pathogens / A. Aguzzi et al.

  • Matt B.

    I would suggest that they confirm the pathway by reinfecting the individuals that are close to death, so that they can examine the olfactory and optic nerves. For all we know, the pathway could be alimentary or pneumonal.

  • wombatarama

    Are you sure I shouldn’t panic that they’ve just described a great idea for a biological weapon that no one will even know is happening till months after it is deployed, when it’s much too late to run away?

  • Brian Too

    At the height of the Mad Cow scare, it became public knowledge that the farming/ranching community had decided that the optimal way to handle infected animals was to “Shoot, Shovel and Shut Up”. To do otherwise was causing farm quarantines and ongoing damage to the industry.

    One wonders how quickly prions degrade in buried cow carcasses. My understanding was that they were pretty tough. If prions could survive for several years in soil, that might provide a disease reservoir that could be a risk factor for people living in the area.

    It would require disturbance of the cow’s grave but that’s not so improbable. Especially if the idea was to have an unmarked, low profile burial site.

  • Craig J.

    I am with wombatarama on this one. There is no cure for “mad cow” disease. Imagine even the huge public health scare of someone claiming they had sprayed this in, say, Mall of America during the Black Friday weekend? With no good way to prove or disprove infection until people start dying, and no way to cure them even if they do…panic, fear, economic repurcussions. Real or not, the pyschological attack alone could be huge.

  • Craig J.

    And, as an addition, if 10 martyrs were willing to inhale this stuff and die themselves in those targeted areas…as soon as public health depts. confirm deaths as a result of mad cow, every person who went NEAR a target during the time frame of the supposed attack will now crowd every Dr., hospital, urgent care, for miles around wanting care/cure. Being told…go home and wait to see if you die? The healthcare system would be overwhelmed and rioting etc. could ensue from people not satisfied with a wait and see response (which is really the only response available).

  • Irresponsible

    I’m a proponent of free speech but don’t you think it’s just a little bit irresponsible to put out the idea of using it as a weapon? I’m sure if you thought of it, it seems obvious, but those of us who don’t spend our time fretting about mostly imaginary terrorist threats are unlikely to make the connection, until you did. Now there’s all the more chance someone will repeat it to a friend, who will tell a friend, who will tell some lunatic who will do it.

  • Idlewilde

    ”slaughterhouse workers who remove brains or spinal chords with bone saws”

    Why do they remove the brain and spinal cord? Does someone like to eat that stuff? I know calf brains are eaten, but calf spinal cords?

    ”Prion labs are not required to use safety equipment that protects workers from aerosols”

    Yes, but are workers required to come to work without a basic dust mask? This is an avoidable danger, even in hazardous workplaces. As for the slaughterhouse workers, give them facemaks and goggles, and have them shower or at least wash their hands after work. Make sure they wear clean uniforms every day. This isn’t a lot of danger if you have knowledge of basic hygiene. Hell, even without the danger of mad cow disease, you’d think a man sawing into flesh would already be wearing some kind of face protection…..

  • Idlewilde


    Don’t worry, it’s kind of difficult to find and puree` enough diseased brain to fill an aerosol can anyway. Not to mention aerosol cans are difficult to fill at home, considering they’re welded shut and all.

  • Craig J.

    And, perhaps someone tells their friend who tells their friend who tells someone who works in the Department of Homeland Security who then considers how to counter a potential threat. Information and ideas can niether hurt nor help without someone acting upon them.

    Idlewild has a point. Look how hard it was for anthrax to actually KILL anybody during the scares of the early 2000’s. The scare itself was more damaging than the spores. This was MY point made. Terrorists, by definition, already know how to maximize terror, no matter the “weapon” of attack.

    Note: given my job I am, in a roundabout way, paid to think up worst case scenarios to
    mitigate their effects if and when they happen. One of my personal fears is I will think of
    something, never express my concern, and see it come to fruition.

  • Brian Too

    @7. Idlewilde,

    It’s my understanding that there’s a use for nearly everything on the cow. The volumes are so high that it’s irresistable to find markets for the most obscure parts (although it need not be to eat). If you can sell it, you convert an expense (waste disposal) to revenue. That kind of logic sells big time.

  • Craig J.

    Brian…terrorists for example. Sorry, BAD joke. Sad to say though, but the brains and spines were often being ground up and put back into cows in the form of high protein feeds.

  • Craig J.

    Sell it to terrorists…my bad.


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