Scientists have found prions — abnormal proteins widely believed to cause a rare, brain-destroying disease — in the skin of 23 patients who had died from it, according to a study published on Wednesday.

The discovery suggests that skin samples might be used to improve detection of the disorder, Creutzfeldt-Jakob disease, which now is usually diagnosed with much more difficult procedures, like brain biopsies or autopsies.

But the presence of prions in the skin also raises unsettling questions about whether medical instruments could become contaminated even during surgery that does not involve the brain and then spread the disease to other patients. The prions stick to stainless steel and are notoriously hard to destroy.

Creutzfeldt-Jakob disease affects one person in a million worldwide, with about 300 cases a year in the United States, according to the National Institutes of Health. People are typically about age 60 when it starts. It is cruel and rapidly fatal: Most patients die within a year of becoming ill.