Froedtert Hospital in Wauwatosa is also notifying about 100 patients who had surgery there this week of the possibility that the disease could be spread by surgical instruments, The Milwaukee Journal Sentinel reported.

Creutzfeldt-Jakob disease, like mad cow disease, is a rare and devastating brain disorder caused by prions, primitive bits of protein. The disease is incurable.

Preliminary tests for the disease were positive in a 79-year-old woman who was in surgery on Monday. But doctors say that false positives are more common and a sample of her brain tissue has been sent to a lab for a conclusive test.

Doctors say it is unlikely that anyone else would be infected even if the disease is confirmed. But they said that ordinary sterilization procedures do not necessarily remove prions.