One in 2,000 people in Britain carry mad cow disease proteins – twice the previous estimates and across a wider age group.
Researchers have compiled the most accurate measure of variant CJD proteins and although the disease is rare, “infection” may be relatively common.
To date there have been 177 cases of Variant Creutzfeldt-Jakob disease , which emerged in the late 1980s and early 1990s through contaminated meat.
Uncertainty remains about how many of the 30,000 people carrying the protein will get the disease and it is not clear what risk carriers pose through blood transfusions or surgery.
Researchers examined more than 32,000 anonymous samples from people who had their appendix removed. Of these, 16 were positive.
But the protein’s presence did not differ significantly in ages, sexes or geographical areas.
Roland Salmon, a retired epidemiologist, said the UK “is well placed” to answer questions on the brain disease.