Prions & Prion Diseases

Prions are a newer discovery in medical science that cause neurodegenerative diseases. What makes a prion unique is that it is not a cell or a living organism that infects the system. Instead, a prion is an infection protein that causes brain tissue proteins to refold, redefining their function. The changes are linked to diseases of the brain such as Alzheimer's disease and bovine spongiform encephalopathy, commonly known as mad cow disease.

Prion Diseases Overview

• Prions affect both animals and humans. Mad cow is the bovine form that is spread to humans after consuming the infected meat. Prions do not die after heat introduction, so the meat is not safe even after cooking. Prions cause the brain's proteins to change form, so the tissue is seen as spongy, which is why the term "spongiform" is used.

Bovine Spongiform Encephalopathy

• Bovine spongiform encephalopathy is more commonly called mad cow disease. The disease first occurred in the United Kingdom and continues to be an outbreak in cattle in the country. The disease was spread by feeding cattle old meat and bones from other animals that were infected with the malicious prion. The first of only three cases in the United State was reported in 2003.

Classic Creutzfeldt-Jakob Disease (CJD)

• There are two forms of CJD: classic and variant. The classic form develops from spontaneous changes of proteins in the brain and is not related to mad cow disease. This type of prion disease is usually fatal within one year of developing the condition. Patients lose memory, personality characteristics and slowly fall into dementia. The risk of classic CJD increases with age. A recognized disease since the early 1920, the United States reports approximately 300 cases annually.

Variant Creutzfeldt-Jakob Disease (vCJD)

• Variant CJD is an acquired condition when patients eat an infected animal, and therefore, unlike classic CJD, age is not a risk factor. Variant CJD has a longer lifespan for patients than classic CJD. The infection acts similar, but the onset of the disease is more gradual. Although the disease is fatal, the risks are low for acquiring the disease even after eating an infected animal.

Prevention

• Since 1996, the CDC has taken precautions against further prion-related infection in the United States. The disease is more common in Europe, but only three cases have been reported in the United States. Mad cow is a reportable disease in which medical examiners are sent to test the cow for any disease. The CDC also requires slaughter house to have surveillance and safety practices in place to prevent prion infection.