Mad Cow Update
 

You can acquire the disease kuru by eating your dead relatives.  Kuru was discovered in the Fore people of Papua New Guinea and was transmitted by ritual cannibalism when the brains and other tissues of deceased tribe members were eaten at funeral feasts.  Kuru, mad cow disease (bovine spongiform encephalopathy, or BSE) and variant Creutzfeldt-Jacob disease (vCJD) of humans, are all caused by prions.  Prion diseases are a group of transmissible, degenerative, uniformly fatal brain diseases with very long incubation periods (the amount of time between infection and the appearance of illness), usually measured in years.

The Same Agent Causes Mad Cow Disease (BSE) and a Human Disease (vCJD)

BSE and vCJD are among the most important prion diseases.  Both BSE and vCJD are caused by the same transmissible agent.  vCJD is a rare but important disease in humans.  The infectious agent which causes BSE can occasionally be transmitted by contaminated beef to humans, causing vCJD.  BSE infections in cattle have also caused significant economic damage to the beef industry.

Cows with BSE behave abnormally and may be aggressive, thus the name "mad cow disease." vCJD usually begins with depression, anxiety, and withdrawal, and then causes problems with walking and speech, hallucinations, mental decline, and death.

Kuru

The first prion disease described in humans was kuru.  Discovered in the Fore people of Papua New Guineau, kuru was more common in women and children because while men ate the flesh of the deceased, the women and children ate the brains, the tissue in which most of the infectious agent is concentrated.

Kuru begins with headache and joint pain, followed by incoordination, tremor, involuntary movements, and mental decline.  Death occurs within 3 months to 2 years.  No one born since this ritual cannibalism ended in the mid-1950s has developed kuru, but those exposed before the practice ended continue to develop the disease as long as 50 years after exposure.

BSE and vCJD Outbreaks in the UK

An outbreak of BSE in cattle began in the UK in the 1980s.  Transmission of the BSE agent to humans in contaminated beef was discovered in the UK when human vCJD cases were reported there in 1996.  There have been almost 200,000 cases of BSE in the UK.  Cooking beef does not appear to prevent infection, but the number of BSE and vCJD infections in the UK has decreased greatly since control measures were adopted there.

So far, 3 BSE infected cows have been reported in the US.  The US has adopted regulations to keep BSE contaminated material out of human and animal food.  The US has also banned the importation of cattle and cattle products from countries with BSE or at risk for BSE.  There have been 2 cases of vCJD in the US, both apparently acquired in the UK.

Stop Eating Beef?

Although the eventual number of people who will develop vCJD is unknown, the disease is extremely rare, even in the UK where almost all of the vCJD cases in the world have been reported.  The US Centers for Disease Control calculated that the risk of getting vCJD in the UK is very low: 1 case per 10 billion servings of beef, and the risk in the US is almost certainly much lower.

Dr. John Bartlett, Chief, Infectious Diseases, Johns Hopkins University School of Medicine, estimated that the risk of getting vCJD from eating beef is "equivalent to the risk of crossing Wolf Street."  Johns Hopkins Hospital is on Wolf Street in Baltimore, Maryland.

 © Copyright 2008  All Rights Reserved.