May incubate mad cow disease in humans

BSE in animals and variant of Creutzfeldt-Jakob Disease in humans

Bovine spongiform encephalopathy (BSE) affects cattle. It is one of the prion diseases which are summarized under the collective term Transmissible Spongiform Encephalopathies (TSE). BSE can be transmitted to humans and is therefore a zoonosis. The most common human form of TSE is Creutzfeldt-Jacob Disease (CJD).

Animal disease

BSE (also called mad cow disease) has a long incubation period and is always fatal. There are no vaccinations or treatment options.

As the disease progresses, abnormally twisted prions accumulate in certain areas of the brain. They lead to a progressive destruction of the nerve cells. The nerve tissue takes on a spongy (= spongiform) appearance. Prions are proteins that occur naturally in every brain in their normal form.

BSE breaks out an average of four to six years after a cattle is infected. Symptoms are increased jumpiness, fear of crossing the manure ditch, of passages, of the smallest obstacles. Further signs are aggressiveness, frequent licking of the nose, grinding of teeth, increasingly stiff gait and hypersensitivity to any external influences. In the final stage, the cattle can no longer get up. In many cases, however, the symptoms are only very weak or not recognizable at all.

Contagion and spread

Cattle can become infected with BSE if they eat insufficiently heated carcass meal that has been infected with prions.

BSE was first discovered in Great Britain in 1986. The first BSE case was diagnosed in Switzerland in November 1990. The database of animal diseases in Switzerland provides an overview of the epidemic situation in Switzerland. For international data see “Further information> Links> OIE”.

Combat in Switzerland

A few weeks after the first BSE case was discovered, Switzerland took key measures:

  • In order to contain the spread of the disease in cattle, the feeding of animal meal to ruminants was banned.

  • In order to protect humans, risk materials such as the brain and spinal cord of cattle have been excluded from the food chain. They still have to be cremated today.

  • Since then, several accompanying measures have been taken, such as a ban on meat and bone meal that applies to all livestock in 2001.
     

In May 2015, 25 years after the first BSE epidemic occurred, the World Organization for Animal Health (OIE) awarded Switzerland the safest country category (country with negligible risk) for BSE (see "Further information> Publications").

What to do?

  • Feeding animal meal to farm animals is prohibited.

  • Animals suffering from BSE must be killed and their meat destroyed in order to prevent infection of other animals or humans.
     

BSE is an animal disease that needs to be eradicated and is therefore notifiable. Anyone who keeps or looks after animals must report suspected cases to the herd veterinarian.

BSE-freedom continues to be actively monitored by taking samples of the brain and spinal cord of cattle in slaughterhouses and analyzing them in the laboratory.

The disease in humans: vCJD

BSE can spread to humans as a zoonosis and occurs in humans as a variant of Creutzfeldt-Jakob Disease (vCJD). The time from infection to outbreak can take anywhere from a few months to 30 years. The symptoms of vCJD are primarily psychological changes, including depression and anxiety. A rapidly progressing decline in mental abilities (dementia), disorders in the coordination of movement sequences (ataxias), muscle twitching and other involuntary movements can also be observed.

It is believed that eating highly infectious bovine material (brain, marrow) is the cause of vCJD. VCJD has not been identified in Switzerland.

See also "Further information> Links> BAG: Creutzfeldt-Jakob disease (CJD)".