Daily MOS: The Errant Proteins of Mad Cow Disease

Portrait of black and white cow eating hay. Domestic animal on santo antao, cape verde.

When you go to donate blood in the US, one of the questions they ask is if you spent three months or more in the UK between 1980 and 1996. If you ate beef from the UK in that time, there could still be a nasty little prion or two hanging out somewhere in your neurons.

Waiting.

Today’s Moment of Science… Mad Cow.

Cows will happily nosh on a variety of foods, but generally hay and grass make up most of the diet for adult cattle. To varying degrees, farmers supplement this with everything from basic vitamin and protein supplements up to some more fantastical dietary additions, like beer and skittles. For real.

There are some things cows should avoid in their diets. Like cannibalism, and brain eating in general. Stick a pin in that.

As did some of my weirder stories from grad school, it all started on a farm in Sussex, England. Several cows fell ill between 1984 and 1985. Symptoms included ataxia, temperament changes like increased aggression, weight loss, abnormal gait, and tremors. Symptoms were generally neurological in nature, so it made sense to have a close peek at the brain when performing necroscopy on the animals.

Bovine spongiform encephalopathy (BSE) was first recognized as a diagnosis in 1987. It’s a prion disease, which we don’t talk about very much because they’re pretty rare. A prion is one of those fuckers that exists to remind us how many zillions of things absolutely must go right continually in order for our bodies to simply function, and how the tiniest thing you never thought could be a thing can fuck you up forever.

A prion is just a protein that’s bent out of shape. The word prion is derived from the phrase “proteinaceous infectious particle,” which accurately indicates something bit sinister. Though these are “just proteins,” they act kinda like infectious agents. While things like bacteria and viruses multiply themselves, you go from one prion to an entire mad cow when that abnormally shaped protein passes its atypical shape onto healthy variants of the same protein in the host. Prion diseases that we’ve identified so far in mammals attack the brain, are progressive in nature, and are always fatal.

It’s commonly believed that BSE came from a feed supplement called meat and bone meal (MBM). Coming from the school of ‘use everything but the oink,’ it’s created from bits of the animal left over from the slaughterhouse. Remains of a cow that spontaneously generated the errant prion or a lamb with scrapie (another prion disease) are suspected to have landed in the mix.

Nearly 200,000 British cows were diagnosed with BSE through the outbreak that peaked in 1993. Cattle cannibalism, i.e. the use of sheep and cattle parts in MBM for use in their feed, was banned in the late 1980s. They also banned human consumption of certain types of organ meats, including brain, spinal cord, thymus, and spleen.

But this just affected cows, right?

In 1990, a siamese cat named Max was infected with BSE. He started acting weird. I mean weird even for a cat.

But just cows and cats, right?

While over four million animals were slaughtered in an attempt to curb the spread, it’s likely that millions of infected cows made it into the food supply. So it was a bitch when people started showing symptoms in 1994.

You might be thinking “wouldn’t general kitchen hygiene and proper cooking technique handle this?” Prions are like “oh, nice sauna you’ve got here that I can survive in forfuckingever.” They’re tough bastards.

Variant Creutzfeldt–Jakob disease (vCJD) can come from contaminated beef or from a blood donation from a person who’s unwittingly carrying the disease from eating contaminated beef.

In a 2018 study, approximately one in 2000 people in England have signs of abnormal prion accumulation. So far, 231 cases of vCJD have been diagnosed worldwide, at least three of which came from blood transfusions.

At this point, cases of BSE seem to be under control. Though there have been cases since the original outbreak, they’ve been fairly isolated and controlled quickly with new standards in place to control for it.

On the other hand, some studies suggest that vCJD can take decades to appear. We’re looking at an upsetting possibility that vCJD might reappear years from now in an unknown percentage of people who had a burger in England in the late 1980s.

This has been your daily Moment of Science, asking you to please donate blood, but read the questionnaire carefully.

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About SciBabe 375 Articles
Yvette d'Entremont, aka SciBabe, is a chemist and writer living in North Hollywood with her roommate, their pack of dogs, and one SciKitten. She bakes a mean gluten free chocolate chip cookie and likes glitter more than is considered healthy for a woman past the age of seven.

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