Almost 40,000 patients who visited a Las Vegas clinic have been told to get tested for hepatitis B and C, as well as HIV, after health officials say they found that nurses there were reusing syringes and dosing out contaminated medicines.

So far, six new cases of hepatitis C have been traced back to the Endoscopy Center of Southern Nevada, officials announced last week in shutting down the clinic. Five of those patients visited the facility on the same day, Sept. 21.

Anyone who was treated at the facility between March 2004 and Jan. 11 has been advised to get tested. Investigators say that nurses often reused syringes on several patients and shared vials of medicines between patients — practices that can spread disease.

A Nevada man who came forward Thursday suggesting he was the source of the Sept. 21 infections said he has had hepatitis C since 2000 and visited the medical centre on that day for a colonoscopy.

"I know it wasn't my fault rationally, but you can't help but feel guilty," the 58-year-old, who asked to remain anonymous, told the Los Angeles Review-Journal newspaper.

"I was there that day. I was one of the first patients treated. I have hepatitis C. Common sense would tell you, it was me."

Majority owner offers no comment

The clinic's majority owner, Dr. Dipak Desai, an immigrant from India who has practised medicine in Nevada since 1980, has not made any public comments on the case.

He did, however, take out an ad in a local newspaper saying, "Some of our patients may have been exposed to blood-borne diseases at our facility. In cooperation with the Southern Nevada Health District and other agencies and officials, we have carefully reviewed our procedures and implemented changes they recommended."

Local police and the FBI are investigating, and at least two class-action lawsuits were filed earlier this week. A third lawsuit against the clinic's doctors, nurses and other staff was filed Wednesday, alleging medical malpractice, fraud, civil conspiracy and negligence.

Three of the Endoscopy Center's sister facilities in Clark County, Nev., have also had their business licenses suspended.

Hepatitis C is a virus of the liver that spreads through direct contact with an infected person's blood and can lead to liver cirrhosis and cancer, though it is not usually fatal. There is no vaccine.