Health officials cautioned them to practice safe sex and use condoms.

At a Wednesday afternoon news conference attended by health officials and doctors from the facility, officials said six people diagnosed with acute hepatitis C in recent months received treatment at the center near Valley Hospital Medical Center. They are believed to have been exposed to the disease when anesthesiologists reused syringes to administer medications.

The Endoscopy Center of Southern Nevada is a high-volume gastrointestinal practice where colonoscopies are frequently performed. Reuse of syringes and vials at the facility was a "common practice" undertaken by everyone from doctors to technicians, health officials said.

The business was investigated for other unsafe practices such as not properly cleaning endoscopic equipment used in colonoscopies and upper gastrointestinal procedures.

The medical facility was open for business Wednesday. It could be subject to sanctions or lose its Medicare contract at a later date, state health officials said.

Dr. Eladio Carrera, a gastroenterologist and internal medicine physician at the center, attended the news conference, but he did not address why he and other staffers did not follow correct medical procedures. In a statement, he expressed concern for patients, then refused to take questions.

Dr. Dipak Desai, the center's administrator, was not at the news event and could not be reached later at the office for comment.

LARGEST SUCH NOTIFICATION

"Las Vegas has the dubious distinction of having the largest patient notification of its kind," one involving the reuse of syringes and consequent spread of disease, said Joseph Perz, an epidemiologist with the federal Centers of Disease Control and Prevention in Atlanta.

Like some Nevada physicians, Perz said, he was stunned by the magnitude of what happened in Las Vegas.

"It certainly is unsettling to think of the scope of this,'' he said. "Let's not forget the impact on people when they receive the notification letter. A lot of people are going to lose sleep.''

Health officials began investigating the endoscopy center in early January after learning of three people who had been diagnosed with hepatitis C, a chronic, potentially lethal blood-borne virus that can cause liver cancer and liver failure.

The three other cases were identified later.

Each of the individuals underwent procedures requiring injected anesthesia at the medical center between June and September 2007. Five underwent the procedures on the same day at the facility, said Brian Labus, the health district's senior epidemiologist.

The health district subsequently notified the Nevada State Board of Licensure and Certification about the hepatitis C cases and the possibility that exposure occurred at the same medical facility.

The board inspects facilities before they accept patients to determine whether they meet construction requirements and health care regulations. The board also evaluates medical facilities to ensure they comply with the law and provide quality patient care.

After a joint investigation by the board and the health district, it was determined that syringes -- not needles -- and the use of vials of anesthesia medication on multiple patients were potential sources of infection.

A syringe would become contaminated by the backflow of blood when patients with a blood-borne disease were injected with medication, health officials said. That syringe, in turn, would be reused to withdraw medication from a different vial. That vial could become contaminated and result in infection.

During the investigation Labus said doctors, nurses and other medical personnel at the facility were asked whether it was the norm to reuse syringes and vials.

"They admitted, 'This is what we were told to do,' " Labus said.

So far there have been no cases of hepatitis B or HIV linked to the endoscopy center that have been reported to the health district.

INCUBANCY MIGHT BE KEY

Dr. Lawrence Sands, director of the health district, said at the news conference that it could be too early in the investigation for reports about HIV to surface, considering the incubation period for symptoms. Depending on an individual's health, symptoms of HIV might not appear for several years.

The incubation period for hepatitis C is six to eight weeks, and only 20 percent to 30 percent of people exposed actually have symptoms, Labus said.

"Hepatitis C is a serious medical condition,'' Sands said.

"As a precaution and in order to take appropriate steps to protect their health, it is important for these people to get tested and for anyone with the illness to seek medical attention.''

Health officials said Wednesday evening they don't believe the hepatitis C cases are the result of colonoscopies or gastroenterology procedures performed at the center, though the state licensing board referenced in its report problems arising from these procedures that could spread infection.

Lisa Jones, chief of the licensure and certification board, said the reuse of syringes and vials of medication were considered more of a public health risk than the fact that endoscopic equipment was not cleaned properly by clinic personnel.

Instead of cleaning one endoscope and then using fresh solution to clean another one, the same dirty solution would be used, the report states. Jones said one batch of cleaning solution should be used for a single endoscope or set of instruments.

But that issue was not raised at the news conference.

"I didn't want to go into too much detail (about the endoscopic equipment) because of time," Jones said in a telephone interview Wednesday evening. "We felt it was significant enough to cite (in the report) as a deficiency."

District Attorney David Roger said his office "will look at all the facts and circumstances of the Health District investigation" before deciding whether criminal charges are warranted.

When asked who would pay the costs of patients getting tested and treated for diseases spawned because of diagnostic procedures, health officials didn't have any immediate answers.

"That hasn't been worked out yet,'' Sands said. "We hope to get that worked out over the weeks that come.''

Dr. Cheryl Hug-English, associate dean of admissions and student affairs for the University of Nevada School of Medicine, said students are taught from their first year of medical school that what transpired at the Endoscopy Center of Southern Nevada "is not an acceptable practice."

"Certainly the standard of care for many years is not to reuse syringes," Hug-English said. "The proper practice is repeated and ingrained that syringes cannot be reused. ... We take this very seriously.''

In residencies, medical students are monitored by program directors on proper practice, she said.

Carrera, accompanied by Drs. Sanjay Nayyar and Clifford Carrol, said in the statement that the center wants "to express our deep concern about this incident to the many patients who have put their trust in us over the years.''

"As always, our patients remain our primary responsibility and we have already corrected the situation.''

Carrera went on to say that the investigation marked the first time "anything like this" has happened at the facility.

He said the center was "officially notified" of the hepatitis C outbreaks Feb. 6 and submitted a detailed plan of correction to the licensing board on Feb. 15.

Jones said the agency conducted an investigation at the facility from Jan. 9 to Jan. 17.

"This is beyond unfortunate,'' Larry Matheis, executive director of the Nevada State Medical Association, said after learning of the possible exposures. "Even in the early days of the HIV epidemic when I was the administrator of the Nevada State Health Division, I don't think we ever had a situation like this. ... I'm sure that's why the red flags went out. It's unusual to have an outbreak of hepatitis C.''

FOLLOW-UP WILL BE NEEDED

Matheis and other Nevada health officials said they couldn't recall such an event involving so many people occurring in the state.

Dr. Don Havins, chief executive officer and special counsel for the Clark County Medical Society, said he was alerted by the health district of the hepatitis C cases but wasn't made aware that five of the six people probably were exposed at the same facility on the same day.

He said that is a major concern because others treated that particular day will need to get tested.

"That's the most important thing right now, getting to those people,'' he said.

Matheis said the issue definitely requires follow up and intensive review.

He said the medical association will send information to all Nevada physicians to alert them about such mistakes. He said there might be a need to review Nevada laws to ensure that measures are in place to prevent future similar incidents.

"The Board of Medical Examiners also should be looking at this as well,'' Matheis said. "This is why we have systems in place, to make sure that patient safety is built-in and redundant practices don't occur.''

Evelyn McKnight, co-founder of Hepatitis Outbreak National Organization for Reform, a national advocacy group, said in an e-mail Wednesday that her heart dropped when she heard that 40,000 Nevadans were being notified they might be exposed to hepatitis C and B and HIV.

McKnight was one of 99 cancer patients infected with hepatitis C while undergoing cancer treatment at a Nebraska oncology center.

"Once again, we have an outbreak that involves two common elements -- an outpatient clinic and the reuse of medical equipment that is intended to be used only once,'' she said. "When we hold our restaurants to higher standards than our doctors' offices, that's a tragedy."

On Wednesday, Angelo Dominic, 76, sat in the medical building that houses the Endoscopy Center of Southern Nevada and shook his head in disbelief. Dominic, now being treated for prostate and heart problems, said he had a colonoscopy at the facility within the last year.

He couldn't believe medical personnel would have reused syringes.

"I was a medic in Korea, and I knew you could never do that," he said.

"I've had to deal with prostate cancer and now I have to worry about hepatitis and HIV. Why can't these people care about other people? Where do they come from?"

Review-Journal writer Carri Geer Thevenot contributed to this report. Contact reporter Annette Wells at awells@reviewjournal.com or (702) 383-0283.