Global Leadership in Education and Research

BSE - Bovine Spongiform Encephalopathy
"Mad Cow Disease"

BSE: bovine TSE

• Bovine Spongiform Encephalopathy (BSE) is a fatal disease that affects the brain of cattle
• BSE is one of several diseases catagorized as Transmissible Spongiform Encephalopathies (TSEs)
• The disease is believed to be caused by a "self-replicating" protein (a prion; PrP^Sc) rather than a bacterium or virus
  
• Meat, blood and milk have not been shown to carry the infective agent
  
• Measures have been taken to exclude tissues that carry the infective agent (i.e. brain & nervous tissue) from the food supply
• No cases of BSE have been reported in the United States

CJD: human TSE

• Creutzfeldt-Jakob Disease (CJD) is a prion disease in humans
• Almost all cases of CJD are spontaneous, inherited or iatrogenic
• A small number of variant CJD (vCJD) cases have been linked to BSE exposure
• Daniel C. Gajdusek discovered the first form of human TSE in the 1950's, called Kuru
• Daniel C. Gajdusek was awarded a Nobel Prize for his work in 1976
• Stanley B. Prusiner was awarded a Nobel Prize in 1997 for his work on prions
• No cases of vCJD have been reported in the United States

BSE was first observed in Great Britain in April, 1984, and was specifically diagnosed in 1986. By June, 1990, there were some 14,000 confirmed cases out of an estimated population of 10 million cattle in Great Britain. Since 1986, nearly 200,000 cases of BSE in cattle have been identified in the United Kingdom. The epidemic peaked in 1992-93 at almost 1,000 cases per week. Control measures have reduced incidence and currently, less than 100 cases are being reported per week.

As June 2001, the disease has been reported in domestic cattle of several European countries including:

• Ireland
• Portugal
• Switzerland
• France
• Germany
• Spain
• Belgium
• Netherlands
• Denmark
• Italy
• Liechtenstein
• Luxembourg
• Greece
• Czech Republic
• and in cattle exported from England to Oman, the Falkland Islands and Canada.

The U.S. Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) has banned importation of live cattle or meat products from BSE-infected countries since 1989 and is conducting surveillance for BSE to ensure that it does not become established in the United States. In 1997, the FDA has also been put in place a ruminant to ruminant feed ban similar to that in Great Britain as an additional safeguard.