I found our study of prions really interesting last week! I had no idea that proteins could be so infectious! The discussion we had about Kuru and other protein diseases reminded me about the media scandal that occurred when we had the mad cow disease crisis a few years ago. I decided to explore more about mad cow disease since it is so relavent in society today and was only briefly mentioned in the readings…
Bovine spongiform encephalopathy (BSE), commonly known as mad cow disease, is a fatal neurodegenerative disease in cattle that causes a spongy degeneration in the brain and spinal cord. BSE has a long incubation period, about 2.5 to 8 years, usually affecting adult cattle at an age of four to five years old. All breeds are equally susceptible to the disease. In the United Kingdom, the country worst affected, more than 180,000 cattle have been infected and 4.4 million slaughtered during the eradication program that occurred.
The disease is most easily transmitted to human beings by eating food contaminated with the brain, spinal cord or digestive tract of infected carcasses. However, the infectious agent, the prion, although most highly concentrated in nervous tissue, can be found in virtually all tissues throughout the body, including blood. In humans, it is known as new variant of Creutzfeldt–Jakob disease, and by June 2014 it had killed 177 people in the United Kingdom, and 52 elsewhere. Between 460,000 and 482,000 BSE-infected animals had entered the human food chain before controls on high-risk offal were introduced in 1989.
A British and Irish inquiry into BSE concluded that it was caused by cattle, which are normally herbivores, being fed the remains of other cattle in the form of meat and bone meal, which caused the infectious agent to spread. The cause of BSE may be from the contamination of food from sheep with scrapie that were processed in the same slaughterhouse.
I thought it was fascinating that the disease spread exactly the same way that the Kuru spread in the case we studied. I hope that future studies will continue to evaluate the causes of prion protein diseases and that we may someday know the origins of where prions originated!