What is bovine spongiform encephalopathy?
Bovine spongiform encephalopathy (BSE), like the other transmissible spongiform brain diseases, is caused by prions. These are misfolded proteins that are deposited primarily in nerve cells and thus damage the brain.
The BSE pathogens are considered dangerous, among other things, because they easily cross the so-called species barrier and infect both animals and humans.
How does BSE develop?
The exact mechanism by which bovine spongiform encephalopathy develops is not yet fully understood. Scientists suspect that the main cause is meat and bone meal used in cattle fattening. Meat and bone meal contains components from carcasses, including those of dead sheep.
In Great Britain, the sheep disease “scrapie”, which is also a transmissible spongiform encephalopathy, has been known for over 200 years. It is suspected that some sick sheep were used for the production of meat and bone meal and thus infected the cattle with the BSE pathogens (prions). The disease spread through the export of meat-and-bone meal and cattle to mainland Europe.
Facts and figures
How does BSE manifest itself in cattle?
Cattle suffering from mad cow disease are on average between four and six years old. They show changes in character and behavior and are extremely fearful or aggressive. Many suffer from movement disorders, fall to the ground and react very sensitively to noise, light or touch. The affected animals die after about six months. There is currently no treatment available.
In addition to classic BSE, there is also atypical BSE. The symptoms are the same as in the classic form. In rare cases, atypical BSE occurs spontaneously in older animals (usually from the age of eight).
How does BSE manifest itself in humans?
Infection with the BSE agent triggers the new variant of Creutzfeldt-Jakob disease (vCJD) in humans. People with the disease suffer from rapidly progressing dementia, uncoordinated movements and mental abnormalities such as depression or hallucinations. Sometimes there are disturbances in the sense of balance or vision.
Read more about Creutzfeldt-Jakob disease here.
How do people become infected?
To date, more than 200 people worldwide have died as a result of BSE. Most of them lived in Great Britain. In Germany, Austria and Switzerland, no cases of the disease have been reported to date. The number of new cases and deaths has fallen in recent years.
It is difficult to say exactly how many new cases there will be, as the incubation period of vCJD – i.e. the time from infection to the outbreak of the disease – has not been conclusively clarified.
How people can protect themselves
In addition to the ban on meat and bone meal and the BSE test, further precautionary measures have been taken to prevent the spread of the disease.
In Germany, for example, people who were in the UK for more than six months between 1980 and 1996 are not allowed to donate blood. In addition, diseased animals are killed and their carcasses destroyed. The import of BSE-infected animals into Germany is also prohibited.