Up to 31,000 People in Britain Carry the Prion for Mad Cow Disease

What this means for the people who silently carry the abnormal protein, however, remains unknown

Rainer Zenz

In Britain, an estimated 31,000 people carry the prion for mad cow disease—twice as many as as experts previously thought, the New Scientist reports.

Weirdly, the researchers had to examine 32,000 appendixes to figure this out. “A decade ago it was discovered that the prion lodges in the appendix, offering a way to search for it in living people who have their appendix removed,” the New Scientist says. Researchers found that about 1 in 2,000 appendixes removed from people born in the possible infection window tested positive, and they extrapolated from there.

About half of those cases involve the genetic form of the protein—that’s the form implicated in the all of the deadly manifestations of mad cow disease. But what this means for the carriers isn’t quite clear. Back in 1996 when the outbreak first occurred, experts feared a mass die-off. But that never happened—just 177 died in the UK.

It could be that the infected people are simply carriers and will never suffer any symptoms, the New Scientist writes. On the other hand, they may be exhibiting symptoms that experts don’t recognize as manifestations of the infection. And there is a chance that some infected persons may come down with mad cow much later in life.

More from Smithsonian.com:

Brain-Eating Crows May Help Spread Prion Diseases 
How Common Was Cannibalism? 

Get the latest stories in your inbox every weekday.