Brain Eaters

The Scariest Afflictions

Friday, May 15, 2026

Some of the scariest ways to die loom larger in the imagination than their realistic threat level would warrant. What sorts of things? Airline disasters. Mad-cow disease—actually, variant Creutzfeldt-Jakob Disease (vCJD). The risk of death from either is about as scant as hen’s teeth, as the expression has it. Maybe a more apt risk analysis would be that catching CJD is about as likely as dying in an airline disaster because the airliner crashed into the couch you were sitting on in your home.

I bring this up because the topic of prion diseases came up the other day in comments. It was something I remembered being worried about during the scare period in the 1990s, when there was a minor eruption in cases of mad cow disease (bovine spongiform encephalopathy: BSE)—mainly reported from the UK. The cases shown in the media were some of the scariest, as are most depicted pathologies that irreversibly and chronically destroy the brain.

As noted, the likelihood of dying in an airline disaster in the United States is very rare. But the imagined horror of falling from the sky to your death makes the scarce risk loom disproportionately large, because terrifying. There’s also the sense that if you were in an airplane experiencing disaster, everything would be out of your personal control.

Catching CJD is also exceptionally rare: about one or two cases per million people. The scary bits are the news videos from the 1990s of people and cows losing motor control and sanity. Seeing victims flail and rave helplessly sticks in the mind. Runner-up in the scariness derby is that there’s no known cure; the disease slowly progresses for some long period of time as the body quietly begins producing these corrupted proteins (prions). By the time it is observed, it’s already too late. Finally, the main way to diagnose it is in post mortem. Otherwise, much else about CJD is only poorly understood.

Rare diseases are hard to study because they are so rare. OTOH, the dramatic rare diseases are studied because they are so dramatic.

The mad cow scare left its mark, in that it made the disease seem more common all at once. It also left the impression that CJD from eating tainted meats was common. Hence, in the comments, there were concerns about eating contaminated venison from afflicted wild animals bearing the related prion disease found in deer and other cervids: chronic wasting disease (CWD). But the official state of current knowledge about prion disease is that 85 percent of cases in humans are sporadic CJD (sCJD)—lacking further explanation. Cases from consumption of affected meat sources (variant CJD, or vCJD) account for about one percent of that low incidence rate. That is to say, it makes up about one percent of the cases of a disease that afflicts one or two per million people.

How do I know all this? Mainly because the internet gives me the superpower of going from bloody ignoramus to PhD expert within 15 minutes or less. But that’s a superpower available to us all nowadays. Hallelujah.

Specific credit goes to the Creutzfeldt-Jakob Disease Foundation and its public information efforts, an example of which is this handy fact sheet. If you peruse that and their site’s other general public information, you’ll see there are a few things that are known, even as much about the prion diseases remains obscure—including the infectiousness beyond species boundaries. CWD, for instance, has not been found to have infected humans—so far. At the same time, a major obstacle to diagnosis is vCJD’s scarcity: the main way found to identify it in humans has been in brain autopsies of human cadavers (or, perhaps, tonsil biopsy of living patients).

In sum, as far as human diseases go, CJD seems among the least worth worrying about. Prion diseases are not much of threat to humans, other than in the spontaneous form. As the CJD Foundation helpfully describes it:

Sporadic CJD (sCJD) occurs for no apparent reason and accounts for 85% of the cases.

Cause: Unknown

Distinguishing Features: Affects mainly people over the age of 60. Common symptoms include ataxia and dementia. Short course. Upon tissue examination there is spongiform change, but plaques are rarely present.