Health Encyclopedia

Mad Cow Disease (Spongiform Encephalopathy or BSE)

Mad cow disease or bovine spongiform encephalopathy (BSE), is a disease was first found in cattle. It's related to a disease in humans called variant Creutzfeldt-Jakob disease (vCJD). Both disorders are universally fatal brain diseases caused by a prion. This is a protein particle that lacks DNA (nucleic acid). It's believed to be the cause of various infectious diseases of the nervous system. Eating infected cattle products, including beef, can cause a human to develop mad cow disease.

What is mad cow disease?

Mad cow disease is a progressive, fatal neurological disorder of cattle resulting from infection by a prion. It appears to be caused by contaminated feed that contains the prion agent. Most mad cow disease has occurred in cattle in the United Kingdom, a few cases were found in cattle in the United States between 2003 and 2006. Feed regulations were subsequently tightened.


In addition to the cases of mad cow reported in the United Kingdom (78% of all cases were reported there) and the U.S., cases have also been reported in other countries, including France, Spain, Netherlands, Portugal, Ireland, Italy, Japan, Saudi Arabia, and Canada. Public health control measures have been implemented in many of the countries to prevent potentially infected tissues from entering the human food chain. These preventative measures appear to have been effective. For instance, Canada believes its prevention measures will eradicate the disease from its cattle population by 2017.

What is variant Creutzfeldt-Jakob Disease (vCJD)?

Creutzfeldt-Jakob Disease (CJD) is a rare, fatal brain disorder that causes a rapid, progressive dementia (deterioration of mental functions), as well as associated neuromuscular disturbances. The disease, which in some ways resembles mad cow disease, traditionally has affected men and women between the ages of 50 and 75. The variant form, however, affects younger people (the median age of onset is 28) and has atypical clinical features as compared with CJD. About 230 people with vCJD have been identified since 1996. Most are from the United Kingdom and other countries in Europe. It is extremely rare in the United States, with only 4 reported cases since 1996.


Currently this risk appears to be very small, perhaps fewer than one case per 10 billion servings--if the risk exists at all. Travelers to Europe who are concerned about reducing any risk of exposure can avoid beef and beef products altogether, or can select beef or beef products, such as solid pieces of muscle meat, as opposed to ground beef and sausages. The solid pieces of beef have a reduced opportunity for contamination with tissues that may harbor the mad cow agent. Milk and milk products are not believed to transmit the mad cow agent. You cannot acquire vCJD or CJD by direct contact with a person who has the disease. Three cases acquired during transfusion of blood from an infected donor have been reported in the United Kingdom. Most human Creutzfeldt-Jakob disease is not VCJD and is not related to beef consumption but is also likely due to prion proteins. Consult your doctor for more information.

Medical Reviewers:

  • MMI board-certified, academically affiliated clinician
  • Turley, Ray, BSN, MSN