A rare, highly virulent and drug-resistant strain of the HIV virus that leads to AIDS has been detected in a New York City man, sparking renewed warnings to the gay community to practise safe sex.

In a statement released Friday, the city’s health department said the new strain, known as 3-DCR HIV , does not respond to three classes of anti-retroviral medication, and also greatly shortens the interval between infection and the onset of full-blown AIDS.

The first case was diagnosed last week in a man in his late 40s who reported multiple male sex partners and unprotected anal intercourse, often while using the highly potent narcotic crystal methamphetamine.

“This case is a wake-up call,” said Health Commissioner Thomas Frieden. “First, it’s a wake-up call to men who have sex with men, particularly those who may use crystal methamphetamine.”

Detection of the new HIV strain came shortly after two New York men were diagnosed with a rare form of the sexually transmitted disease chlamydia, and Frieden said both cases should send alarm bells ringing in the gay community.

“This community successfully reduced its risk of HIV in the 1980s, and it must do so again to stop the devastation of HIV/AIDS and the spread of drug-resistant strains,” he said.

“Now we’ve identified this strain of HIV that is difficult or impossible to treat and which appears to progress rapidly to AIDS,” he added.

The onset of AIDS usually occurs more than 10 years after initial infection with the human immunodeficiency virus (HIV). But in the case diagnosed last week, the time lag appeared to be just two to three months.

More than 88,000 New Yorkers are known to be living with HIV/AIDS, and an estimated 20,000 are believed to be infected without knowing it.