Abnormal proteins involved in the brain-destroying Creutzfeldt-Jakob disease (CJD), a human form of "mad cow" disease, are detectable in the skin, according to researchers, raising new concerns about transmission.
It is highly unlikely that the fast-moving and fatal disease could be spread by casual contact, since the prions in the skin are at levels 1,000-100,000 times lower than in the brain, said the report in the journal Science Translational Medicine.
Rather, researchers said the discovery means CJD could be spread through common surgeries that do not involve the brain, said the report.
Only biopsies, spinal taps or autopsies can tell for sure if a patient is stricken with the rare, degenerative brain disorder which affects one in a million people per year worldwide.
Patients develop tiny sponge-like holes in their brains, and experience sudden memory and vision problems, behavioral changes and poor coordination.
There is no cure for CJD and most people who are diagnosed rapidly deteriorate, and die within a year.
The study was based on skin samples from 38 patients who died from the disease.
Prion levels were measured using a new, highly sensitive test.
Research using lab mice showed that these skin prions are indeed infectious, and capable of causing disease.
But more research is needed to better understand the risks.
The findings may also assist in diagnosing the condition less invasively, whether before or after death.