Mad Cow DiseaseMad Cow DiseaseAre humans susceptible?Are humans susceptible?

By Lacy D LapioBy Lacy D Lapio

What is Mad Cow Disease?What is Mad Cow Disease?

• Mad Cow Disease is scientifically known as Bovine Spongiform Encephalopathy (BSE).

• BSE affects the central nervous system of cattle, destroying brain tissue and eventually causing dementia and death.

• The nature of the transmissible

agent is unknown.• There is no known cure. • The disease is carried in nervous system tissue.

What is Mad Cow Disease?What is Mad Cow Disease?

• The infectious agent that is widely thought to cause disease is the prion (although that is speculative – there is a lack of evidence), a particle of clumped-up protein.

• In its normal form, the prion protein is found in a wide variety of tissues throughout the body, including the brain, immune system, blood, gut, and liver, and causes no disease. But mutations in the protein can cause it to fold abnormally and clump up to form infectious prions.

• Researchers also believe that new prions can form when a normal prion protein comes into physical contact with an abnormally shaped prion protein. For reasons that are still unknown, the bad protein makes the good protein turn bad.

What causes Mad Cow What causes Mad Cow Disease?Disease?

• Although the cause is unknown, Scientists speculate that the disease has spread among cattle primarily through "animal recycling" -- the use of bone meal and other ground animal parts in feeds.

• Mad cow disease was first identified in Britian in 1985.

• BSE does not

spread from

cow-to-cow contact

What is being done about What is being done about it?it?

• The European Union implemented new rules Jan. 1, 2001 requiring all cattle over 30 months old to be tested for the disease.

• The FDA prohibits all material from non-ambulatory cattle in human food, removing certain cattle tissues

from the human food,

and banning certain

nervous system tissues

in meat products.

Source: FDASource: FDA

Source: Rutgers Poll 2.2.04Source: Rutgers Poll 2.2.04

What is the human variant of What is the human variant of Mad Cow Disease?Mad Cow Disease?

• The human form of Mad Cow disease, Creutzfeldt-Jakob disease (CJD) is a rare, degenerative, invariably fatal brain disorder.

• Typically, onset of symptoms occurs at about age 60.

•There are three major categories of CJD: sporadic CJD, hereditary CJD, and acquired CJD

What causes CJD?What causes CJD?• In sporadic CJD, the disease appears even though the person

has no known risk factors for the disease. This is by far the most common type of CJD and accounts for at least 85 percent of cases.

• In hereditary CJD, the person has a family history of the disease and/or tests positive for a genetic mutation associated with CJD. About 5 to 10 percent of cases of CJD in the United States are hereditary. 

• In acquired CJD, the disease is transmitted by exposure to brain or nervous system tissue, usually through certain medical procedures. There is no evidence that CJD is contagious through casual contact with a CJD patient. Since CJD was first described in 1920, fewer than 1 percent of cases have been acquired CJD.

Source: Source: http://www.mydna.com/health/diseases/madcowhttp://www.mydna.com/health/diseases/madcow

How is it detected?How is it detected?• There is currently no one diagnostic test for CJD. • First it is important to rule out treatable forms of

dementia such as encephalitis or chronic meningitis. • The only way to confirm a diagnosis of CJD is by brain

biopsy or autopsy by removing a small piece of brain tissue to be examined by a neurologist.

• Early symptoms in humansinclude insomnia, memory loss, and depression.

                                    

 Brain tissue infected with prions has a spongy appearance.Image courtesy NEJM.

What is the treatment and What is the treatment and prognosis?prognosis?

• Due to the lack of knowledge of what causes it, there is no treatment that can cure or control CJD

• Around 90 percent of patients die within the first year. In the early stages of disease, patients may have failing memory, behavioral changes, lack of coordination and visual disturbances. As the illness progresses, mental deterioration becomes pronounced and involuntary movements, blindness, weakness of extremities, and coma may occur in the patient.

What link is there between What link is there between bse and cjd?bse and cjd?

• “We don’t know much about how the disease is transmitted or why only certain people appear susceptible,” says Richard Johnson of Johns Hopkins University in Baltimore, Maryland, who headed a recent Institute of Medicine panel to study mad cow and related diseases. “There are too many questions and not enough answers.”

• An experimental study reported in June 1996 showed that three cynomologus macaque monkeys inoculated with brain tissue obtained from cattle with BSE had clinical and neuropathological features strikingly similar to those of variant CJD.

• A study published in 1996 indicated that a Western blot analysis of infecting prions obtained from 10 variant CJD patients and BSE-infected animals had similar molecular characteristics that were distinct from prions obtained from patients with other types of CJD (Nature 1996;383:685-90).

Source: Source: http://www.mydna.com/health/diseases/madcowhttp://www.mydna.com/health/diseases/madcow

What do most americans What do most americans believe?believe?

Of those who had heard of the disease, 65 percent believe the nation’s beef supply is safe, 24 percent believe it is unsafe and 10 percent are unsure.

Source: Rutgers Poll 2.2.04Source: Rutgers Poll 2.2.04

How does this affect the How does this affect the economy & beef market?economy & beef market?

•The EU has set aside about $1 billion for the tests, which cost about $100 per animal. The European Commission estimates the cost of incinerating slaughtered animals at $3.3 billion.

• Nearly 1 in 5 (19.5 percent) of those who knew about mad cow disease say they have since reduced their beef consumption. About 9 percent say they eat somewhat less beef, 5 percent say they eat much less and nearly 5 percent say they have stopped eating beef altogether. As such, about 4 percent of the total population claims to have stopped eating beef.

Source: Rutgers Poll 2.2.04Source: Rutgers Poll 2.2.04

• Nearly a quarter (24 percent) of 19.5 percent of those who have claimed to have stopped eating beef say they will never resume eating it.

How does this affect the How does this affect the economy & beef market?economy & beef market?

Source: Rutgers Poll 2.2.04Source: Rutgers Poll 2.2.04

Should you avoid Should you avoid hamburgers?hamburgers?

• The average annual CJD death rate in the United States has remained relatively stable at about one case per million population per year. In addition, CJD deaths in persons aged <30 years in the United States remain extremely rare (<1 case per 100 million per year).

Source: Source: http://www.mydna.com/health/diseases/madcowhttp://www.mydna.com/health/diseases/madcow

Questions about my Questions about my research?research?

• Contact me at LLapio@smu.edu

Where did I get this Where did I get this information?information?

• http://www.pbs.org/newshour/bb/health/mad_cow.html

• http://www.mad-cow-facts.com/News-Commentary/rutgers_poll_2-2-04.htm

• www.genomenewsnetwork.org/. ../01/23/mad_cow.php

• http://www.fda.gov/fdac/features/2004/304_cow.html

• http://www.mydna.com/health/diseases/madcow

• http://www.ninds.nih.gov/disorders/cjd/detail_cjd.htm