Guest Author - Anita Grace Simpson

Do you remember the scare about Mad Cow Disease? The panic started in Britain, then spread to other countries, even though Britain was the only country with significant numbers of people who fell ill as a result of eating diseased beef. Scientists tell us that these particular brain disorders are not caused by bacteria or viruses, but by prions. Okay -- so what is a prion?

About 40 years ago (according to National Institutes of Health), researchers in infectious disease began to suspect that another disease-causing agent existed besides the usual bacteria, viruses, and fungi. Certain human and animal forms of encephalopathy (brain disease), such as Mad Cow disease and Creutzfeldt-Jacob disease, caused the brain to become spongy as it degenerated, ultimately causing death. No one knew what caused this degeneration, but experiments revealed that the unseen cause of the diseases was unaffected by ultraviolet radiation. This type of radiation, one form of which causes sunburn, will kill the DNA or RNA present in bacteria, viruses, and fungi. So they knew that the agent couldn’t be one of those three.

Further research found the surprising result that the disease agents were damaged by chemicals that break up proteins. This meant that the agents most likely did not contain nucleic acids (DNA/RNA) and did contain proteins. Controversial theories developed – could a protein alone cause illness? How would it be transmitted? How would it reproduce without DNA or RNA?

Scientists had to wait until the mid-1980’s to receive confirmation of the existence of infective proteins. This was a Nobel Prize-winning discovery for researcher Stanley Prusiner!

Although the proteins themselves exist throughout the bodies of humans and animals, they don’t become disease agents (prions) unless they begin to fold into abnormal structures. Sometimes this is caused by inherited factors; other times it results from an infective mechanism such as eating beef from cows with Mad Cow disease. More often, according to the Merck Manual, cases have no apparent risk factors and are considered spontaneous or sporadic.

Regardless of how the first prion develops, it soon turns the normal proteins around it into more prions, and the process continues, eventually (perhaps many years later) producing symptoms of the disease. Brain function is impaired as the prion-infected cells die in clumps, producing the “holes” in the sponge. Patients experience dementia, madness, and eventually, death.

At present there is no cure for any prion disease. Fortunately they are very rare in humans. It is highly unlikely that you or anyone in your family will get one of these diseases, even if questionable beef leaks into the food supply. However, it is wise to be cautious when you hear reports of such a leak. Follow the guidelines published by the Food and Drug Administration.

In the meantime, intensive research into prions is producing new discoveries! Sign up for the Public Health Newsletter to keep abreast of developments in this and other Public Health fields.