Bovine spongiform encephalopathy

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Cow with BSE showing abnormal posturing and weight loss
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Mad cow disease, or bovine spongiform encephalopathy (BSE), is a disease that affects cows. In humans, the disease is called variant Creutzfeldt-Jakob Disease (vCJD). The two types of BSE are "classical" BSE and "atypical BSE". Classical BSE has nearly been eradicated due to implemented control measures, and it's assumed that humans can contract classical BSE and that it causes vCJD; according to the World Organisation for Animal Health, the "hypothesis that BSE prions have been passed to humans, causing vCJD, is strongly supported by epidemiological and clinicopathological studies." Atypical BSE is thought to be a natural, yet still very rare, condition appearing spontaneously in cattle.[1] As of the 2020s, atypical BSE was more common.[2]

Though it is rare in humans, we can contract the disease through eating infected meat (but don't worry, if you die of CJD, it's much more likely you'll die of the form unrelated to cows).[3] CJD debilitates and later kills the infected person, taking between eight weeks and a couple of years, and is 100% fatal.

The brains and spinal cords of infected animals are considered more infectious than other parts, and there are thus "rules against beef processors using the brains or spinal cords of the animal to make food products".[4]

Because of this, you still can't give blood in the USA if you were in the United Kingdom for more than three months total from 1980 to 1996.[5] In 2008, the disease caused a stir in South Korea when the government lifted a ban on U.S. beef imports,[6] since Korean beef dishes tend to contain more offal than those in the US. However, part of the outrage was sparked by misinformation and pseudoscience,[7] as well as opposition to America's economic hegemony and Neoliberalism.[8]

The occasional woo merchant or general brain donor will come up with some mulch about BSE being an alien disease,[9] or more specifically, alien energies.[10]


Our best theory as to the mechanism behind Mad Cow Disease, and other transmissible spongiform encephalopathies, is that it's not caused by a virus or a bacterium or a parasite or a congenital condition, but instead by a misfolded protein called a prion.

Prions are fascinating molecules. Like all protein molecules, they are chains of amino acids. In general, every protein molecule in your body does its job because of its shape; the way a given amino acid chain is "folded" in three-dimensional space determines what kinds of other molecules it can capture, latch on to, twist apart, etc. Normally, every amino acid chain will fold in one specific, predictable manner as it's being assembled from one end to the other. However, in a few cases, the same amino acid chain can be folded into a very different shape after it's been assembled, if it's acted upon by the proper outside force. This will make the molecule incapable of performing the duty that its old shape had.

Prions (PrPSc) are, amino-acid-for-amino-acid, identical to a nerve tissue protein called PrPC. However, they're folded in a radically different manner, which causes them to be extremely protease-resistant, almost impervious to disinfection, and one of, if not the most powerful toxin in the world. They act as catalysts to re-fold PrPC into new prions. Thus, one prion will, when introduced into neuronic tissue (such as brain tissue), create more PrPSc.

This quasi-self-replicating behavior has led some to speculate as to whether prions should be considered a form of life (but, like viruses, prions do not respire, which is by some definitions a requirement for life).

Frustratingly, prions don't break down in the presence of acid or heat — their new structure is far more stable than PrPC. This means that neither cooking nor the digestion process can remove prions from infected cow brains.[11]

Cows were not the first species known to be infected by prion diseases. The sheep disease scrapie is now known to be very similar to mad cow disease. Spongiform encephalopathy first reached epidemic proportions in cows, however, due to the practice of grinding up the undesirable parts of a slaughtered cow (including the brain) and feeding this protein meal to other cows. Since the alarm bells were raised for mad cow disease, this practice has been discontinued.

See also[edit]

External links[edit]


  1. "Bovine spongiform encephalopathy". World Organisation for Animal Health.
  2. Anand Chandrasekhar (September 16, 2023). "Is mad cow disease making a comeback?". SWI swissinfo (Swiss Broadcasting Corporation).
  3. Risk of death from variant Creutzfeld-Jacob Disease (vCJD) and CJD in the UK (2007) Bandolier, University of Oxford (archived from April 17, 2015).
  4. What is Mad Cow Disease?
  5. Eligibility Reference Material American Red Cross.
  6. Anti-U.S. beef protest draws 100,000 S.Koreans. Reuters.
  7. Mad Cow Thesis Twisted All Out Of Proportion.
  8. The 2008 Candlelight Protest in South Korea: Articulating the Paradox of Resistance in Neoliberal Globalization. Huikyong Pang.
  9. Mad Cow Research: Small Steps, Big Questions by Amanda Onion January 6, 2006, 5:56 AM) ABC News.
  10. Alien invasion and mad cow disease by Peter Farley (2006-12-12) (archived from July 31, 2016).
  11. Doppel: More rival than double to prion by Kefeng Qin et al. (2006) Neuroscience 141(1):1-8. doi:10.1016/j.neuroscience.2006.04.057.