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Health and Disease

Prions and Associated Diseases

In the last thirty years, a significant finding in the world of medicine was the discovery of prions. Essentially, prions are misfolded proteins that can cause neurodegenerative diseases. One of the earliest cases of a prion-caused disease was scrapie, a disease afflicting sheep.

By Saharsh Satheesh

Published 5:50 PM EST, Sun March 14, 2021

Introduction

In the last thirty years, a significant finding in the world of medicine was the discovery of prions. Essentially, prions are misfolded proteins that can cause neurodegenerative diseases. One of the earliest cases of a prion-caused disease was scrapie, a disease afflicting sheep. The disease may take several years to develop, but once its symptoms are noticeable, a sheep usually has less than six months to live. In the months following the first symptoms, such as nervousness and behavioral changes, the sheep may begin to lose weight and become unable to maintain muscle coordination.

The main method by which animals are infected with prions is ingestion; prions can be found in urine, saliva, and dead animals. These prions can also be transferred if one comes in contact with infected nervous tissue. For instance, ingesting infected meat may cause the formation of prions. Additionally, a mistake in translation of mRNA to a protein may cause a prion to develop.

Mad Cow Disease

Another disease caused by prions is BSE (bovine spongiform encephalopathy), more commonly known as Mad Cow Disease. The disease was first discovered in the 1970s, and current research hypothesizes that prions are the cause of the disease. The disease affects the nervous system, and one of its first symptoms is the inability to coordinate movements. Similar to scrapie in sheep, cows usually have less than six months to live after the first symptoms are noticed.

How does the disease spread in cows? The disease is spread when a cow is fed the flesh of farm animals that have bovine origin proteins in it. In order to prevent the spread, the solution was to implement a ban against feed that contains mammalian-origin proteins.

However, according to the FDA rules and regulations, “while the prevalence of BSE in the United States is very much lower than in European countries with BSE, evidence from the European experience has demonstrated that, in countries with a high level of circulating BSE infectivity, measures on only ruminant feed were not sufficient to eliminate all transmission of BSE; new cases continued to be found in cattle born in the United Kingdom after implementation of a ruminant-to-ruminant feed ban.”

Creutzfeldt-Jakob disease

An example of a prion-caused disease in humans is known as Creutzfeldt-Jakob disease (CJD). Both Mad Cow Disease and CJD are transmissible spongiform encephalopathies (TSEs), but CJD is only present in humans. Early symptoms of CJD include memory loss and reduced coordination, but as the disease progresses, those affected may mentally decline and go into a coma.

There are three common forms of CJD: sporadic, familial, and acquired. Sporadic CJD (sCJD) is the most common form, and it generally occurs in those over the age of fifty. This form of CJD is when a protein randomly misfolds. Familial CJD is far less common than sCJD, and this form is caused by inherited CJD. This form of CJD is noticeable at a younger age than sCJD. Lastly, acquired CJD is the rarest form, and it usually occurs when one comes in contact with infected tissue.

Saharsh Satheesh, Youth Medical Journal 2021

References

“About BSE BSE (Bovine Spongiform Encephalopathy).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 9 Oct. 2018, www.cdc.gov/prions/bse/about.html.

“CREUTZFELDT – JAKOB DISEASE (CJD) AND MAD COW DISEASE.” 2011. PDF file. https://dhss.delaware.gov/dph/files/cjdmadcowfaq.pdf

Federal Register, Volume 73 Issue 81 (Friday, April 25, 2008), http://www.govinfo.gov/content/pkg/FR-2008-04-25/html/08-1180.htm.

“Prion Diseases.” Johns Hopkins Medicine, http://www.hopkinsmedicine.org/health/conditions-and-diseases/prion-diseases.

“Prion.” Wikipedia, Wikimedia Foundation, 17 Feb. 2021, en.wikipedia.org/wiki/Prion#:~:text=It%20has%20been%20recognized%20that,make%20it%20rearrange%20its%20structure.

“Prion.” Wikipedia, Wikimedia Foundation, 17 Feb. 2021, en.wikipedia.org/wiki/Prion.

“Scrapie.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., http://www.britannica.com/science/scrapie.

What Are Prions?, http://www.prionalliance.org/2013/11/26/what-are-prions/.

“What Is Scrapie?” Scrapie Canada, scrapiecanada.ca/about-scrapie/.

Yan, Yu, and Yu Yan. Fact Checking Project on the Film Fresh, 2 Sept. 2014, blogs.commons.georgetown.edu/cctp-638-yy326/claims-and-facts/are-cows-eating-dead-cows-as-feed/#:~:text=Bovine%20Spongiform%20Encephalopathy%20(BSE)%2C,animals%20that%20are%20probably%20infected.&text=As%20a%20result%2C%20cows%20might,eating%20dead%20cows%2C%20just%20indirectly.

By Saharsh Satheesh

Saharsh Satheesh is a junior in high school. He has a passion for biology and plans to study medicine in college.

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