A week after 40,000 people from Nevada found out that unsafe medical procedures might have infected them with Hepatitis C or the AIDS virus, five certified nurse anesthetics gave up their licenses today until authorities learn why a surgical center reused syringes and vials for four years, the Las Vegas Sun reports.

The nurses worked at the Endoscopy Center of Southern Nevada, where a scandal usually associated with Third World countries began on February 28.

Six acute cases of Hepatitis C have been confirmed and thousand of patients are urged to be tested for the viruses. The surgical center, as well as five affiliated clinics, has been shut down. The FBI, the Nevada attorney general and Las Vegas authorities are currently investigating them.

"I find it baffling, frankly, that in this day and age anyone would think it was safe to reuse a syringe," said Michael Bell, associate director for infection control at the national Centers for Disease Control and Prevention, according to the Associated Press.

One of the infected persons is Michael Washington, 67, who had received a routine colon exam at the Las Vegas clinic in July. His first symptoms appeared in September, and by January he was diagnosed with hepatitis C.

Hepatitis B and the HIV virus may have also been spread, but scientists mostly fear about the hepatitis C, which is easier to transmit than HIV and shows no symptoms in about 80 percent of infections.

Clinic staff told health investigators they were ordered by administrators, especially by majority owner Dr. Dipak Desai, to reuse supplies and medications, in order to save money.