Health officials said Friday a man has been diagnosed with a rare strain of highly drug-resistant HIV that quickly progressed to AIDS (search).

"We are not aware of another case like this in the United States, or elsewhere," said Dr. Ron Valdiserri, deputy director of the Centers for Disease Control and Prevention's (search) National Center for HIV, STD, and TB Prevention.

The case was found in a man in his mid-40s who had unprotected sex with other men, often while using crystal methamphetamine (search), an addictive stimulant.

Health Commissioner Dr. Thomas Frieden said the rare HIV strain is "difficult or impossible to treat." City health officials are working with the CDC to find other possible cases.

The man — who had not previously undergone antiviral drug treatment — was diagnosed with the rare strain in December 2004. He apparently had been infected recently after years of having unprotected anal intercourse.

The onset of AIDS appears to have occurred within two to three months, and at most 20 months, after infection.

Drug resistance is increasingly common among HIV-positive people, including some who had never been treated before, but not with such a fast progression to AIDS, Valdiserri said. HIV can take as many as 10 years to develop into AIDS, Frieden noted.

The man's HIV did not respond to three of four types of antiviral drugs most commonly prescribed; he is now receiving a fourth regimen, health officials said.