There is probably no more horrific and frightening incurable disease than Creutzfeldt-Jakob disease (CJD). Also known as the human form of mad cow disease, this degenerative, always fatal brain disorder strikes about one person in every million worldwide each year, according to the National Institute of Neurological Disorders and Stroke (NINDS). CJD results in the brain literally being turned into sponge-like, hole-filled tissue (the reason the disease is also known as  spongiform encephalopathy). It usually runs a rapid course, causing failing memory, hallucinations, lack of coordination and visual disturbances followed by total mental deterioration, involuntary movements, blindness and coma.

Although some cases are known to be caused by eating meat containing mad cow disease-causing infectious prions, by far the most common form of the illness is known as sporadic CJD. The NINDS says sporadic CJD accounts for at least 85 percent of the cases. Supposedly, sporadic CJD just strikes out of the blue for no particular reason. But Spanish scientists say they’ve found compelling and disturbing evidence that people are infected with the disease during operations.

“Based on the monitoring records of spongiform encephalopathy in two Nordic countries, we studied the possibility of transmission of the sporadic form of CJD through general surgery,” Jesus de Pedro, main author of the study and head of prion monitoring in patients at the National Epidemiology Center of the Carlos III Health Institute in Madrid, said in a statement to the press.

The research team’s study, just published in the Journal of Neurology, Neurosurgery and Psychiatry, came to this startling conclusion: the sporadic form of CJD strikes after a person has surgery — usually at least 20 years after an operation. The data suggests, Dr. DePedro stated, the disease enters and spreads much more quickly within the central or peripheral nervous system due to surgical procedures.