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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 the United States or Canada.2, 1 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.

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).

In December 2003, mad cow disease was discovered in one cow in the United States. Before this cow was found to have the disease, the cow was slaughtered and its muscle meat was sent to be sold in grocery stores. But its organs and nerve tissue were not used for human food. Although mad cow disease cannot be spread through muscle meat, the United States Department of Agriculture (USDA) quickly traced the meat and removed it from grocery stores.

Since 2004, only three more cows in the United States have been found to have mad cow disease. The most recent case of BSE was found in April 2012 in a cow in California.

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 the 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 behavior.
  • 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.

  • 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 http://www.cdc.gov/ncidod/dvrd/bse.
  • 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.
  • Health Canada 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.
  • 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

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
Web Address: www.cdc.gov
 

The 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.


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.


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


USDA Food Safety and Inspection Service
Web Address: www.fsis.usda.gov

References

Citations

  1. Canadian Blood Services (2005). Deferral policies for vCJD. Available online: http://www.bloodservices.ca/CentreApps/Internet/UW_V502_MainEngine.nsf/page/Deferral+Policies+for+vCJD?OpenDocument.
  2. American Red Cross (2009). Eligibility requirements: Donating blood. Available online: http://www.redcrossblood.org/donating-blood/eligibility-requirements.

Other Works Consulted

  • Bosque PJ, Tyler KL (2010). Prions and prion diseases of the central nervous system (transmissible neurodegenerative diseases). In GL Mandell et al., eds., Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases, 7th ed., vol. 2, pp. 2423–2438. Philadelphia: Churchill Livingstone.
  • 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
E. Gregory Thompson, MD - Internal Medicine
W. David Colby IV, MSc, MD, FRCPC - Infectious Disease
Last Revised March 21, 2013

This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

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