About BSE and other TSEs
BSE is one of a group of diseases that affect a number of different mammals. These diseases, known as Transmissible Spongiform Encephalopathies (TSEs), or Prion Diseases, result from the build-up of abnormal prion proteins in the brain and nervous system. TSEs get their name from the spongy appearance in the infected brain, and the fact that they are transmissible via infected material.
Bovine Spongiform Encephalopathy (BSE) is a disease that affects adult cattle. BSE affects the central nervous system of the animal, particularly the brain, and eventually causes death.
Often referred to as 'Mad-Cow Disease', BSE has a long incubation period. This means that it usually takes four to six years for cattle infected with BSE show signs of the disease, such as disorientation, clumsiness and, occasionally, aggressive behaviour towards other animals and humans.
A widespread prion disease of sheep and goats is classical scrapie. This disease affects sheep and goats and is found in many different countries, including most European countries.
Classical scrapie has been seen in UK flocks for over 250 years, and while some of the signs of the disease are very similar to BSE – it attacks the nervous system of sheep and goats and causes death – studies have not shown any link between scrapie and human illness.
More recently, scientific tests have identified another TSE disease in sheep and goats, called atypical scrapie.
Where did BSE come from?
BSE was first confirmed in cattle in 1986. Despite much research, however, no one can say with certainty where BSE came from, although several theories exist.
Cattle are grazing animals that do not naturally eat meat. Most experts agree that BSE was most likely spread by cattle eating feed that contained meat-and-bone Meal (MBM), made from BSE-infected tissues. MBM was produced in a process called rendering; this turned otherwise unused animal products into animal feed.
Experiments have shown that cattle can contract BSE if they are fed infected brain tissue. This seems to support the idea that BSE was transmitted to cattle through their animal feed.
The practice of feeding MBM to cattle, and all other farm livestock is now banned.
What danger is BSE to people?
BSE develops in cattle, but it belongs to a family of prion diseases, several of which can affect humans. The most commonly known disease in this group among humans is Creutzfeldt-Jakob Disease (CJD). This is a rare and fatal form of dementia that mainly occurs in individuals between the ages of 40 and 80.
CJD is not a new disease among humans, but in 1996, scientists discovered a new strain of CJD that occurs predominantly in younger people.
More recent evidence has shown that the protein that accumulates in the brains of individuals with this new form of CJD is similar to the protein found in cattle infected with BSE, rather than that found in classical CJD. Because of this difference, the new illness in humans is known as variant CJD or vCJD.
The occurrence of a new form of CJD in the UK, where there was a high incidence of BSE, suggested that there might be a direct link between BSE and vCJD. Some individuals who have developed vCJD are known to have eaten potentially BSE-infected meat products. Researchers concluded that the most likely origin of this new disease was human exposure to the BSE agent.
Like BSE in cattle, vCJD is always fatal in people. As of Nov 2010, 174 probable or definite cases of vCJD had been diagnosed in the UK.
How widespread is BSE?
Since 1989 cases of BSE have been reported in the following countries: Austria, Belgium, Canada, Czech Republic, Denmark, Falkland Islands, Finland, France, Germany, Greece, Ireland, Israel, Italy, Japan, Liechtenstein, Luxembourg, the Netherlands, Oman, Poland, Portugal. Slovakia, Slovenia, Spain, Sweden, Switzerland and the United States.
The epidemic in the UK has been in decline for many years.
With the decline in BSE cases the UK is now, along with other EU Member States, classified in the controlled risk category as determined by the European Union (EU).
Why was BSE so common in the UK before effective controls were introduced?
We still do not know how BSE started in the UK. But extensive use of MBM in cattle feed in this country meant that, once it started, BSE spread rapidly.
Where can I go for more information?
For further information on BSE and to find out about the latest research, please call the Food Standards Agency on 020 7276 8829, or email: helpline@foodstandards.gsi.gov.uk.
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BSE and beef
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BSE Controls Breaches
These reports provide updates on any BSE controls breaches.