Mad Cow Disease

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Mad Cow Disease

Overview

What is mad cow disease, and does it infect people?

Mad cow disease is a fatal disease that slowly destroys the brain and spinal cord (central nervous system) in cattle. It also is known as bovine spongiform encephalopathy, or BSE.

People cannot get mad cow disease. But in rare cases they may get a human form of mad cow disease called variant Creutzfeldt-Jakob disease (vCJD), which is fatal.

This can happen if you eat nerve tissue (the brain and spinal cord) of cattle that were infected with mad cow disease. Over time, vCJD destroys the brain and spinal cord.

There is no evidence that people can get mad cow disease or vCJD from eating muscle meat—which is used for ground beef, roasts, and steaks—or from consuming milk or milk products.

People with vCJD cannot spread it to others through casual contact.

People who have spent a lot of time (at least 3 months) in places where mad cow disease has been found are not allowed to give blood in Canada or the United States.1, 2 This is to help prevent vCJD from spreading.

What causes mad cow disease and variant Creutzfeldt-Jakob disease (vCJD)?

Experts are not sure what causes mad cow disease or vCJD.

The leading theory is that the disease is caused by infectious proteins called prions (say "PREE-ons"). In affected cows, these proteins are found in the brain, spinal cord, and small intestine. There is no proof that prions are found in muscle meat (such as steak) or in milk.

Another theory is that mad cow disease is caused by a virus that causes the proteins to change.3

When a cow is slaughtered, parts of it are used for human food and other parts are used in animal feed. If an infected cow is slaughtered and its nerve tissue is used in cattle feed, other cows can become infected.

People can get vCJD if they eat the brain or spinal cord tissue of infected cattle.

How common are mad cow disease and vCJD?

The first case of vCJD was reported in 1996. Since then, there have been a few cases of vCJD reported in the world. Most of the cases have been in countries that are part of the United Kingdom (England, Scotland, Wales, and Northern Ireland).

Since May 2003, seventeen cows suspected of having mad cow disease have tested positive for BSE in Canada. No meat from these cows entered the human food supply. For more information on BSE in Canada, contact the Canadian Food Inspection Agency or see the agency's website: www.inspection.gc.ca.

What are the symptoms of vCJD?

Variant Creutzfeldt-Jakob disease (vCJD) causes the brain to become damaged over time. It is fatal. Symptoms include:

  • Tingling, burning, or prickling in your face, hands, feet, and legs. But there are much more common illnesses that cause these same symptoms. Having tingling in parts of your body does not mean you have vCJD.
  • Dementia.
  • Psychotic behaviour.
  • Problems moving parts of the body. As the disease gets worse, a person is no longer able to walk.
  • Coma.

If a person does eat nerve tissue from an infected cow, he or she may not feel sick right away. The time it takes for symptoms to occur after you're exposed to the disease is not known for sure, but experts think it is years.

How is vCJD diagnosed?

There is no single test to diagnose vCJD. Doctors may think that a person has vCJD based on where the person has lived and the person’s symptoms and past health. Imaging tests, such as an MRI, may be done to check for brain changes caused by vCJD.

Researchers are now trying to develop a blood test that looks for vCJD. But no blood test is available at this time.

A brain biopsy is the only way to confirm a diagnosis of vCJD.

How is vCJD treated?

There is no cure for vCJD. Treatment includes managing the symptoms that occur as the disease gets worse.

Latest Information

The following health organizations are tracking and studying mad cow disease and variant Creutzfeldt-Jakob disease (vCJD). Their websites contain the most up-to-date information about these diseases.

  • Public Health Agency of Canada (PHAC) answers frequently asked questions about mad cow disease and vCJD and provides information about infection control and food inspection. You can find information at www.phac-aspc.gc.ca/cjd-mcj/index-eng.php.
  • Canadian Food Inspection Agency (CFIA) answers questions and provides updates on BSE in North America. It also offers information about infection control and food inspection. You can find information at www.inspection.gc.ca/english/anima/disemala/bseesb/bseesbe.shtml.
  • U.S. Centers for Disease Control and Prevention (CDC) provides up-to-date information about mad cow disease and variant Creutzfeldt-Jakob disease (vCJD), including tracking, prevention, travel precautions, and food inspection. You can find information at www.cdc.gov/ncidod/diseases/submenus/sub_bse.htm.
  • U.S. Department of Agriculture (USDA) provides information about mad cow disease, the safety of the meat supply in the United States, and infection control guidelines. You can find information at www.fsis.usda.gov/Fact_Sheets/Bovine_Spongiform_Encephalopathy_BSE/index.asp.
  • The World Health Organization (WHO) website offers information about mad cow disease and vCJD cases around the world and provides infection control guidelines. You can find information at www.who.int/csr/disease/bse/en.

Other Places To Get Help

Organizations

Canadian Food Inspection Agency
Phone: 1-800-442-2342
(613) 225-2342
TDD: 1-800-465-7735
Email: To send an email, go towww.inspection.gc.ca/english/util/contact/commene.shtml
Web Address: www.inspection.gc.ca
 

The Canadian Food Inspection Agency (CFIA) is Canada's federal food safety, animal health, and plant protection enforcement agency. The CFIA has inspection programs related to foods, plants, and animals across Canada. The agency enforces the food safety and nutritional quality standards established by Health Canada and, for animal health and plant protection, sets standards and carries out enforcement and inspection.


Genetics Home Reference, U.S. National Library of Medicine
8600 Rockville Pike
Bethesda, MD  20894
Phone: 1-888-FIND-NLM (1-888-346-3656)
Fax: (301) 402-1384
TDD: 1-800-735-2258
Web Address: www.ghr.nlm.nih.gov
 

The Genetics Home Reference provides information on hundreds of genetic conditions. The website has many tools for learning about human genetics and the way genetic changes can cause disease. It also has links to additional resources for people who have genetic conditions and for their families.


Public Health Agency of Canada (PHAC)
130 Colonnade Road
A.L. 6501H
Ottawa, ON  K1A 0K9
Phone: Telephone numbers for PHAC vary by region. For your regional number, go to the listing on the PHAC website at www.phac-aspc.gc.ca/contac-eng.php.
Web Address: www.phac-aspc.gc.ca/index-eng.php
 

The Public Health Agency of Canada (formerly the Population and Public Health Branch of Health Canada) is primarily responsible for policies, programs, and systems relating to disease prevention, health promotion, disease surveillance, community action, and disease control.


U.S. Centers for Disease Control and Prevention (CDC)
1600 Clifton Road
Atlanta, GA  30333
Phone: 1-800-CDC-INFO (1-800-232-4636)
TDD: 1-888-232-6348
Email: cdcinfo@cdc.gov
Web Address: www.cdc.gov
 

The U.S. Centers for Disease Control and Prevention (CDC) is an agency of the U.S. Department of Health and Human Services. The CDC works with state and local health officials and the public to achieve better health for all people. The CDC creates the expertise, information, and tools that people and communities need to protect their health—by promoting health, preventing disease, injury, and disability, and being prepared for new health threats.


U.S. National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health
NIAID Office of Communications and Government Relations
6610 Rockledge Drive, MSC 6612
Bethesda, MD  20892-6612
Phone: 1-866-284-4107 toll-free
Phone: (301) 496-5717
Fax: (301) 402-3573
TDD: 1-800-877-8339
Web Address: www.niaid.nih.gov
 

The U.S. National Institute of Allergy and Infectious Diseases conducts research and provides consumer information on infectious and immune-system-related diseases.


References

Citations

  1. Canadian Blood Services (2011). Deferral policies for vCJD. Available online:http://www.blood.ca/CentreApps/Internet/UW_V502_MainEngine.nsf/page/vCJD+An+Introduction?OpenDocument.
  2. American Red Cross (2009). Eligibility requirements: Donating blood. Available online: http://www.redcrossblood.org/donating-blood/eligibility-requirements.
  3. Manuelidis L, et al. (2007). Cells infected with scrapie and Creutzfeldt-Jakob disease agents produce intracellular 25-nm virus-like particles. Proceedings of the National Academy of Science, 104(6): 1965–1970.

Other Works Consulted

  • González-Scarano F (2008). Transmissible spongiform encephalopathies section of Central nervous system diseases due to slow viruses and prions. In DC Dale, DD Federman, eds., ACP Medicine, section 11, chap. 17. Hamilton, ON: BC Decker.
  • U.S. Centers for Disease Control and Prevention (2010). Fact sheet: Variant Creutzfeldt-Jakob disease. Available online: http://www.cdc.gov/ncidod/dvrd/vcjd/factsheet_nvcjd.htm.

Credits

By Healthwise Staff
Primary Medical Reviewer E. Gregory Thompson, MD - Internal Medicine
Primary Medical Reviewer Anne C. Poinier, MD - Internal Medicine
Specialist Medical Reviewer W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Last Revised May 31, 2011

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