Surgery carries a small risk

The prion proteins that cause the brain disease can stick to instruments and be passed on to others who subsequently undergo surgery.

Cleansing chemicals have proved to be ineffective, or harmful, to the equipment and the environment.

However, the Health Protection Agency in Porton Down has developed an enzyme-based treatment that safely digests the rogue proteins.

When prions are exposed to the solution at a temperature of 60C, they become almost a million times less infectious.

The active component comes from bacteria found in volcanic pools.

Researcher Dr Neil Raven said: "We have developed a safe and inexpensive, but highly sensitive, method that enables us to detect tiny amounts of these prion proteins.

"This method has been tested on the surface of stainless steel therefore simulating surgical instruments."

Small risk

The risk of contracting CJD from surgery is tiny. The greatest risk is posed by neurosurgery.

However, it is thought that some other organs, such as the tonsils and the appendix, may also harbour prions.

Surgical instruments used on people who are known to have CJD are quarantineed after use, and then destroyed.

However, some people may undergo surgery without doctors knowing that they pose a risk.

Sporadic CJD occurs spontaneously in the general population with no known cause or triggering event.

vCJD is a simlar neuro-degenerative disease, but generally occurs in younger people.

Scientists believe vCJD is caused by eating meat infected with BSE.

There are about 35 to 70 cases of CJD each year in the UK. Most are of the sporadic form. In total, 136 people in the UK have died from vCJD.