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Mad Cow Disease


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).



What are the symptoms of vCJD?


  • Dementia.
  • Psychotic behavior.
  • Coma.


How is vCJD diagnosed?




How is vCJD treated?


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
  • 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
  • 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
  • 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

Other Places To Get Help


Centers for Disease Control and Prevention (CDC)
1600 Clifton Road
Atlanta, GA 30333
TDD: 1-888-232-6348
Web Address:


Genetics Home Reference, U.S. National Library of Medicine
8600 Rockville Pike
Bethesda, MD  20894
Fax: (301) 402-1384
TDD: 1-800-735-2258
Web Address:


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:


USDA Food Safety and Inspection Service
Web Address:



  1. Canadian Blood Services (2005). Deferral policies for vCJD. Available online:
  2. American Red Cross (2009). Eligibility requirements: Donating blood. Available online:

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:


By Healthwise Staff
E. Gregory Thompson, MD - Internal Medicine
Last Revised March 21, 2013

