VARIANT CJD - the human form of mad cow disease - may never disappear from the UK due to the risks from blood transfusions and surgical equipment, a leading expert in the disease has warned.
Professor James Ironside, of the National CJD Surveillance Unit at Edinburgh University, said that unless a rapid screening test for vCJD is developed soon, the fatal infection could become endemic in the UK.
Prof Ironside will issue the warning at a major conference in Edinburgh this week on vCJD.
Concerns have been raised that the disease - caused by humans eating meat infected with the cattle disease BSE in the 1980s and 1990s - could be lying dormant in thousands of people.
While many will never develop the disease, they could pass it on to others by donating blood or through contaminated surgical instruments if they have an operation.
Prof Ironside said the National Blood Transfusion Service had already gone to great lengths to protect the blood supply, screening and filtering donations to try to reduce the risks from vCJD.
Also, after the first case of vCJD through blood transfusion was identified, people who had previously received blood were banned from donating.
But he said that the nature of the infection, which is not destroyed by heat treatment or decontamination of surgical equipment, meant it continued to be a significant issue.
"If you make certain assumptions about the number of people who might be infected with vCJD, because we know that with BSE many of us were exposed, and what the incubation periods might be, it is possible to arrive at a scenario where vCJD will never completely disappear.
"It will remain at a low level, an endemic level, maintained by secondary transmission. That is something that is very undesirable and should be avoided."
Graham Steel, co-founder of the CJD Alliance and the information resource manager of the CJD International Support Alliance, said: "We are closer than ever before to actually implementing new screening technologies to prevent further secondary infection of these diseases. The latest published research that I am aware of clearly demonstrates this.
"The time has almost come for screening to become a reality."
Marc Turner, of the Scottish National Blood Transfusion Service, said:
"We believe that the risk of transmission of vCJD by blood transfusion is low but that a highly precautionary approach is justified."
SPREAD OF THE DISEASE
VARIANT Creutzfeldt-Jakob Disease (vCJD) was first identified in 1996.
Patients with vCJD develop brain damage which eventually leads to death.
It was passed to humans through the food chain in meat infected with BSE. The disease spreads to the brain in tiny proteins called prions, which are extremely difficult to destroy using normal methods.
So far, 166 cases of vCJD have been diagnosed in the UK, but it is impossible to know how many more people could be affected but are not showing symptoms.
Scotland and the north of England have been worst hit by the disease.
Scotland has seen 4.12 cases per million people, compared with 2.03 in Wales and 2.8 cases per million in the south-east of England.