Mad Cow Mad Cow DiseaseDisease

袁聖甯 黃竹瑄 鄧雯心袁聖甯 黃竹瑄 鄧雯心

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

• A kind of transmissible spongiform encephalopathies (TSE)

• Occurs in many mammals, including human• Cow: -Bovine Spongiform Encephalopathy(BSE) -progressive neurological degeneration • Human: -Creutzfeldt-Jacob disease (CJD) -new variant of CJD (vCJD).

• In which country ? United Kingdom (U.K)

• By what reason ? By feeding cattle with meat-and-bone meal from BSE-infected cattle.

•When was BSE first reported ? November, 1986

Important facts about Important facts about the history of BSEthe history of BSE

• The vast majority of BSE cases have been reported in the U.K.

• The U.K. epidemic peaked in January 1993 at nearly 1,000 new cases per week.

• Among Britain’s 34000 herds of cattle, 176000 cattle were infected in 2000.

What countries have had What countries have had BSE ?BSE ?

• A widespread outbreak infected more than 100,000 cows across Europe in the mid-1990s.

• Recent cases are reported in Japan, Canada, and America.

• Surveillance in Europe has also led to the identification of cases of BSE in Belgium, Denmark, France, Ireland, Switzerland, Germany, Spain, and Italy.

• What’s the human form of TSE? -There are 6 kinds of TSE occur on humans. -Kuru (the earliest discoverd) -Creutzfeldt-Jacob disease (CJD) -variant Creutzfeldt-Jacob disease (vCJD)• The origin of human TSE : -1957 -Kuru -In the Fore natives of the New Guinea highlands. -The Fores were cannibals.• Scientific Research : -Kuru was first diagnosed in 1920. -Dr. Prusiner found the cause of the disease. -He won a Nobel Prize in 1997.

Why do we fear BSE?Why do we fear BSE?

• In 1996, scientists found a possible link between BSE and a new variant of CJD (vCJD).

• Evidence indicates that humans may acquire vCJD after consuming BSE-contaminated cattle products.

• From 1995 through early December 2000, 88 human cases of vCJD were reported in the U.K.

Is this possible in the Is this possible in the future?future?

This is a mad cow…….This is a mad cow…….

Why is BSE = mad cow ?Why is BSE = mad cow ?• Irritable• Violent• Threatening fashion when a

pproached by humans

• The most plausible cause of the disease is a prion, an abnormal form protein.

The pathogen of BSE The pathogen of BSE • The mechanism of prion--

prion

Normal protein

Explanations Explanations for the prion theory for the prion theory

• Two forms:PrPc PrPsc

• The two kinds of protein are different in 3D structure.

• PrPsc can accumulate and leading to amyloid changes and giosis.

Routes of infection Routes of infection • Acquired infection

– Diet – Growth hormone injection

s – Corneal transplants –

• Heredity – The human PrP-gene (PRN

P) is localized on the short arm of chromosome 20.

– Mutations

ClinicalClinical symptom in vCJDsymptom in vCJD• The decline of memory • The abnormal behaviors • The inharmonious gait • The fierce spasm • The body incapable

Control and Control and PreventionPrevention

• UK ─ banned using any ruminant (cattle, sheep, goats) or ruminant by-products in animal feed in 1988.

• banned exports of cattle to other countries.

• destroyed BSE-infected cattle and monitored herds for signs of BSE.

• monitored the general population and reported any cases of nvCJD

The U.S. government has The U.S. government has instituted the following policies instituted the following policies

regarding BSE: regarding BSE:

• USDA has prohibited imports of live ruminants or ruminant products from Europe.

The USDA inspects all cattle used for food for signs of neurological diseases..

The U.S. Food & Drug Administration (FDA) has prohibited using

mammalian proteins in making animal feeds for ruminants.

The FDA has recommended that pharmaceutical companies should not use animal tissues from countries with BSE in making drug products (vaccines).

• The FDA has asked blood centers to exclude potential blood donors who have spent six or more consecutive months in the UK between 1980 and 1986.

The Centers for Disease Control (CDC) regularly monitors the U.S. population for signs of nvCJD.

The USDA has tested any cattle showing abnormal behavior for BSE.

• The CDC has issued guidelines to travelers in Europe:

1.avoid beef and beef products altogether 2.if eating meat, then select beef or beef products that have less opportunity for contamination from nervous tissue (solid muscle cuts vs. processed sausages or hamburgers)

3. milk or milk products are not believed to pose any risk from the BSE agent

The National Institutes of Health (NIH) conducts research on BSE, CJD, nvCJD and related nervous system diseases.

Current news

conclusionconclusion• “If an evil force could devise an agent capa

ble of damaging the human race, he would make it indestructible, distribute it as widely as possible in animal feed so that it would pass to man, and program it to cause disease slowly so that everyone would have been exposed to it before there was any awareness of its presence,” British microbiologist, Richard Lacey.

The End

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