ATLANTA - Emory University Hospital has not adopted the most rigorous type of sterilization on surgical instruments after learning Sept. 15 that a brain surgery patient may have spread a fatal mad cow-like disease to more than 500 patients, a federal health official said Friday.

The best medical sterilization measures call for using a chemical Emory is not using and more intense heating, said Dr. Ermias Belay, an epidemiologist with the U.S. Centers for Disease Control and Prevention in Atlanta. Belay helped write the sterilization guidelines.

Emory also waited two weeks after the initial patient's probable diagnosis of Creutzfeldt-Jakob disease before informing other patients they were possibly exposed, subjecting dozens of people to brain or spine surgery without their knowledge of the risk.

"I think we had every right to be informed," said Susan Nabulsi, whose husband Mike Nabulsi had neck surgery on Monday, long after Emory knew of the concern. "We were not given an informed choice." In all, 516 patients are facing an uncertain future, knowing that years from now they could develop a fatal disease that has no treatment, even though the risk is small.

The sterilization issue involves three tiers of cleaning methods aimed at ridding instruments of disease. Nearly all hospitals use a basic level for routine care, as Emory did. Emory is now using an enhanced level in response to the Creutzfeldt-Jakob situation. Some health officials call for what they say is an even higher level when dealing with the disease.

Emory officials say their current, stepped-up sterilization techniques, adopted Sept. 15, have been approved by health authorities and exceed those performed at many hospitals under similar circumstances.

Since the measures are thought to nearly eliminate the risk of spreading the disease, and nothing can be done to prevent or treat the condition, there was no rush to tell former or upcoming surgery patients, Emory officials said.

"It made no sense to inform people scheduled (for surgery) on, say, the 18th," said Dr. William Bornstein, who is in charge of quality control at the hospital. "We didn't believe they were at increased risk." Yet on Thursday, 15 days after the risk was known, Emory began calling and sending letters to 98 patients who had neurosurgery Sept. 10-27 to inform them that they might be at risk. The hospital also notified 418 other patients who had other types of surgery at the hospital during that period.

Both groups face a "remote" chance of infection, though the neurosurgical patients have a slightly higher risk, Emory officials said.

The initial patient is believed to have sporadic Creutzfeldt-Jakob disease, which is related to variant Creutzfeldt-Jakob disease, known as human mad cow disease. Both are caused by prions, misshapen proteins that can stick to surgical instruments and are hard to destroy.

The condition -- which cannot be spread through casual contact -- causes dementia, poor balance, muscle jerks and eventually death. It can take a few years or even decades before symptoms arise. Once they do, patients die within a year.

Only four cases are known to have been transmitted through neurosurgical instruments worldwide, in Europe before 1976.

Routine sterilization measures used in most hospitals today greatly reduce the risk, said the CDC's Belay. But when a suspected or confirmed Creutzfeldt-Jakob case is linked to surgical instruments, hospitals are instructed to enhance sterilization.

The most stringent technique involves immersing the instruments in sodium hydroxide and heating them in an autoclave at 273 degrees or higher for 18 minutes, or 250 degrees for an hour, Belay said. The procedure is recommended by the CDC and the World Health Organization.

Emory uses an enzyme solution that doesn't include sodium hydroxide and autoclaves at 270 degrees for 18 minutes, Bornstein said. While the Emory method is approved by the health agencies as an alternative, it is not as good, Belay said.

"The most important thing is the combination of sodium hydroxide with some form of autoclaving," he said.

An alert issued in 2001 by the Joint Commission on the Accreditation of Healthcare Organizations also recommended sodium hydroxide, which can dissolve brain tissue remaining on instruments. The notice followed situations similar to Emory's at hospitals in Denver and New Orleans, which involved a total of 14 patients notified of possible exposure.

The hospital accreditation agency's alert also discussed other steps to reduce risk: quarantining instruments until a definitive diagnosis is made, discarding them or using ones that are disposable.

Emory is not using sodium hydroxide because it is corrosive and can destroy instruments, Bornstein said. He said disposable instruments often aren't sturdy enough.

Until the recent incident, the hospital's policies called for quarantining instruments -- removing them from circulation until the disease is confirmed or ruled out. But Bornstein said that approach can be dangerous, because the instruments can be put back into play based on poor information.

Quarantines are instituted when surgeons think a patient may have Creutzfeldt-Jakob or when a biopsy suggests the disease. But doctors can't identify every case and biopsies can be wrong. An Australian hospital notified more than 1,000 patients of possible exposure last month after a surgery patient whose biopsy was negative died and an autopsy found the disease.

"We think the right approach is assuming every brain biopsy could come in contact with" Creutzfeldt-Jakob, Bornstein said. Emory has started using its newly adopted sterilization on equipment from all brain biopsies.

The initial patient, who is still alive, did not have rapidly progressive dementia, poor coordination or muscle ticks, so doctors didn't think she had Creutzfeldt-Jakob, said Dr. Allan Levey, chairman of Emory's neurology department. He said brain scans and brain wave tests on the patient showed no signs of the disease.

Definitive test results on the unidentified patient may not come for several weeks. Emory said it sent tissue samples to the National Prion Disease Pathology Surveillance Center at Case Western Reserve University in Cleveland.

Pathologists there perform gene sequencing and protein typing tests to confirm the disease, said Carrie Harris, manager of the center. It received samples from 280 possible cases last year, with 60 percent testing positive.

Sporadic Creutzfeldt-Jakob, for which a source is rarely found, strikes about 300 Americans a year.

Bornstein said that if any of the 516 patients Emory has alerted ever develop memory loss or other symptoms of neurological disease, they are much more likely to have a common disease like Alzheimer's than Creutzfeldt-Jakob.

That is little comfort to the Nabulsis, who are planning to retire to Aruba next year. Mike, 64, is an electrician whose neck surgery was performed to treat progressive nerve disease. Susan, 53, is a former travel agent.

They returned home from the hospital Thursday and two hours later got the call from Emory about possible exposure to the disease. They realize the risk is small, but Susan Nabulsi said the worry will always linger, even on the sunny Caribbean island of their dreams.

David Wahlberg writes for The Atlanta Journal-Constitution. E-mail: dwahlberg@ajc.com Editor Notes:Story Filed By Cox Newspapers For Use By Clients of the New York Times News Service

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