DENVER (AP) — Two patients have died at a Colorado hospital this year from Creutzfeldt-Jakob Disease, an illness similar to the mad-cow disease, and there is concern other patients may have been exposed, a hospital spokeswoman said Friday. The patients, both over 60, died in January and February at Exempla St. Joseph Hospital, said Steve Krizman, a spokesman for Kaiser-Permanente, the health maintenance organization that cared for them. Hospital spokeswoman Kathleen Ferguson said at least six other patients may have been exposed to Creutzfeldt-Jakob through surgical instruments used while treating one of the two who died. The instruments were sterilized after each use, but no studies have been done to show whether sterilization procedures are effective against the proteins that cause the disease, said Dr. Cathy van Blerkom, chair of the hospital's Department of Pathology and Infection Control. "There are a lot of unknowns in this disease," she said. Creutzfeldt-Jakob Disease, or CJD, attacks the brain, killing cells and creating gaps in tissue. The brain takes on a sponge-like appearance. Early symptoms include memory problems, mood changes and lack of coordination. The disease progresses to shakiness and dementia. Victims are eventually unable to move or speak. A separate form of the disease has been linked directly to eating meat from cattle infected with bovine spongiform encephalopathy, or mad-cow disease. Nearly 100 people in Europe have died of the disease since 1995. About two cases of CJD are reported in Colorado every year, said Cindy Parmenter of the Colorado Department of Public Health and Environment. "We had four in 2000 and two or three in years before that," Parmenter said. "It usually happens in people 60 and older. It's not totally unusual." Copyright 2001 Associated Press.