Learn Your Germs: What is Mad Cow Disease?

"mad_cows," by justthatgooguyjim on Flickr Creative Commons

As I was writing my toxoplasmosis post, I realized there is a far more topical disease to discuss: it was recently announced that a dairy cow in California was diagnosed with BSE (bovine spongiform encephalopathy). “Mad Cow Disease” is a concern, of course, because eating meat from a cow with BSE is strongly linked to variant Creutzfeldt-Jakob Disease (vCJD) in humans. vCJD is a pretty awful, inevitably fatal neurodegenerative disease with a long, unpredictable incubation period. Luckily, it is super rare. To date, only a handful of variant cases have been confirmed in the United States. (A sporadic form of the disease, sometimes referred to as “classic CJD,” is thought to occur through an endogenous mutation rather than from outside sources, such as eating BSE-infected meat. It is more common than vCJD but also very rare.)

Interestingly, BSE and CJD are believed to be caused by prions, infectious agents researchers are still struggling to fully understand. Unlike bacteria and viruses, prions don’t contain DNA or RNA. Infectious prions are misfolded proteins that are believed to cause normal proteins around them to also become deformed. Because they are so different than typical infectious agents, prions are resistant to methods we use to detect and kill bacteria and viruses… As it so happens, prions aren’t even really alive.

As for this latest bovine illness, the Department of Agriculture has been quick to reassure the public that they believe the case poses no danger to humans... I guess I’ll put this in my terrifying-but-not-likely category, nestled somewhere along my anxiety spectrum between ebola and bear attacks.

 Here’s what the CDC has to say about prion diseases and vCJD. For a great read on prions, check out The Family That Couldn’t Sleep.