Since the big scare of Mad Cow disease in the 90s, the number of cases of people infected with the human form of the disease has been steadily declining. But a new study in Britain, where the disease was first diagnosed, found one in two thousand Britons may still harbor the mutated proteins called prions.

Prions are misfolded proteins which convert healthy proteins into misfolded ones that build up over time. In humans, Mad Cow, known as Bovine spongiform encephalopathy, is variant Creutzfeldt Jakob disease or vCJD. It's passed onto people when they eat infected beef neurological material, such as spinal cord and brain, as well as the spleen and tonsil.

The study tested for presence of specific prions in thirty two thousand donated appendices and sixteen were positive which extrapolates to one in two thousand in the general population. But that doesn't mean all those people will develop the disease because it's possible in some people, the protein may not lead to vCJD.

Prion build up in the brain causes plaques that eventually cause brain damage. Once people begin showing symptoms, most die within eight months. There is no treatment or cure. So far one hundred seventy seven Britons have died from vCJD.

Scientists had believed the incubation period for vCJD was about eight years, but now they think that there are at least three variants of the misfolded prion protein. So, many more people could be unaware they have the disease. Since there is no blood test for vCJD, carriers of it could unwittingly pass on this disease to others when they give blood.

Hopefully, blood tests will be developed to protect against the inadvertent transmission of vCJD. Much has been done on farms to prevent the spread of Mad Cow, but further foolproof approaches are still needed.