Wednesday, April 25, 2012

Real Facts about Mad Cow Disease

Bovine Spongiform Encephalopathy (BSE), commonly known as mad-cow disease, is a fatal neuro-degenerative disease in cattle that causes a spongy degeneration in the brain and spinal cord. BSE has a long incubation period, about 30 months to 8 years, usually affecting adult cattle at a peak age onset of four to five years, all breeds being equally susceptible. 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. 

The disease may be most easily transmitted to human beings by eating food contaminated with the brain, spinal cord or digestive tract of infected carcasses. However, it should also be noted that the infectious agent, 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 Creutzfeldt–Jakob disease (vCJD or nvCJD), and by October 2009, it had killed 166 people in the United Kingdom, and 44 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.

Humans can’t get mad cow disease

For all the fuss over mad cow disease, otherwise known as bovine spongiform encephalopathy (BSE), it’s actually not transmittable to humans. Those mad cows can, however, contract a form of the disease that is transmittable to humans called variant Creutzfeldt-Jakob disease (vCJD), which, although technically not mad cow, is just as unpleasant and deadly. The strain is always fatal in cows, and usually fatal in humans within 13 months of symptoms occurring.

You won’t get it from eating steak

Often when there’s a mad cow outbreak, panicked people stop eating red meat which is then pulled from supermarket shelves. But humans can’t get the disease by simply eating regular cow meat. Generally, a human will only be infected if they eat the nerve tissue—brains or spinal cord—of an infected animal. People cannot get the disease by simply eating muscle meat like ground beef or steak, or by drinking milk from an infected cow. Additionally, humans cannot spread it to each other through casual contact. However, people who have spent more than 3 months in an area where many cases of mad cow disease have been reported aren’t allowed to give blood in the U.S.

Humans don’t necessarily get CJD from cows

It’s unlikely that humans can contract Creutzfeldt-Jakob disease by eating mad cow-contaminated meat. There are three types of CJD, including a hereditary version of the disease which accounts for roughly 10 percent of all cases. About 85 percent of these cases are considered Sporadic CJD, where the patient has no known risk factors. There is an acquired form of CJD, which accounts for less than 1 percent of patients struggling with the disease. It’s usually transmitted when a person is exposed to infected brain or nervous system tissue during medical procedures.

If you’re infected with CJD, you probably won’t know it until years later

Symptoms of vCJD include tingling sensations and trouble moving parts of the body. As the disease worsens, the victim will lose the ability to walk. The disease can also cause brain damage and lead to psychotic behavior, dementia, and coma. Worst of all, there’s no cure for vCJD and people usually die within 13 months of showing symptoms. Furthermore, it can take up to 15 years for symptoms to manifest themselves.

Mad cow was first discovered in 1986

Mad Cow disease was first discovered in Great Britain in 1986. However, it’s highly likely that the first infections occurred sporadically in the 1970s.

Mad cow is extremely rare in the United States

Cases of Mad Cow Disease in humans or in cows are exceedingly rare in the U.S. There have only been three cases before the current outbreak—in 2003, 2005, and 2006. The only confirmed cases of vCJD in humans in the U.S. have eventually been traced back totime spent in other countries.  However, the disease is quite deadly when it does occur. The outbreak in the United Kingdom that peaked in 1993 killed 180,000 cows and 150 people.

Latest case caused by ‘random mutation’

The mad cow in central California didn’t contract the disease by consuming infected cattle feed, the U.S. Agriculture Department has confirmed. Furthermore, the case could have easily gone undiscovered, since the deceased cow showed little symptoms of the disease and tests are performed on a random selection of dead cows. Specialists are attributing this strain of BSE to a “random mutation,” which means there’s little risk of a large outbreak.

Mad cow destroys the brain and spine in cattle

What makes mad cow disease so deadly? Caused by a deformed protein known as a prion, the disease attacks and destroys the brain and spinal cord in cattle. Humans usually contract the CJD variant by consuming infected brain or spinal tissue, which in turn can cause sponge-like holes in the brain.

Tell Me About Prions
  • Simply put, prions are proteins that can cause disease.
  • Prions aren't alive, so you can't kill them. Proteins can be inactivated by denaturing them (e.g., extreme heat, certain chemical agents), but these same processes usually destroy food, so there isn't an effective method to decontaminate beef.
  • Prions naturally occur in your body, so they are not recognized as foreign and don't stimulate the immune system. They have the potential to cause disease, but won't automatically harm you.
  • Disease-causing prions may physically contact normal prions, altering them so that they too can cause disease. The mechanism of prion action is not well understood.

Thoroughly cooking meat won’t help

You could scorch the meat, roast it into shoe leather, nuke it beyond recognition, and boil it for hours on the stove, but that won’t protect you from the deadly CJD variant. The prions aren’t affected by heat or other methods used to kill food-borne pathogens. Prions can survive in extremes, requiring upwards of 1,800 degrees of heat to be neutralized. Even sterilization processes used by hospitals are largely ineffective.

Mad cow is on the decline

Good news! Mad cow disease is far less common than it was 10 years ago. Last year, there were 29 cases worldwide, a 99 percent decline since the disease peaked in 1992 with 37,311 cases. So now we can go back to worrying about salmonella and E. coli.

It is not possible to get Mad Cow Disease from Milk

The milk supply is safe. Prion diseases affect the nervous system, and there's no evidence they've ever been transmitted by drinking milk.

There is no known cure for Mad Cow Disease

the reality is that all prion diseases cause death. There are no effective treatments available. Progression from symptoms to diagnosis to death may be rapid (from 8 months for sporadic CJD to up to 60 months for GSS).
Continuing laboratory testing is looking at a number of medications to prevent development of prion disease in animals. Work continues on experimental vaccines to delay or prevent the effects of prion disease.

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