While women may have achieved a grim parity with men in contracting the AIDS virus worldwide, experts in the United States remain concerned about the disease's rebound among young gay men.

Today's epidemic has not brought the devastation seen in the 1980s and early 1990s, when AIDS cut a swath through the gay community. But health officials and activists say they are alarmed by high rates among gay teen-agers and young adults - some of whom were not alive during the urgent safe-sex campaigns of those days.

"They didn't see the decimation that we did 15 years ago," said John Hylton, a researcher with the Johns Hopkins Bloomberg School of Public Health who has studied AIDS trends among young men.

"They couldn't see guys walking down the street covered with [cancerous] lesions. They didn't see healthy men who dwindled over time."

Experts say a complacency may have settled in since the advent of drug therapies that are keeping many patients alive and healthy enough to work. Also, they say, some older men have grown tired of curbing their sexual practices.

From Baltimore to San Francisco, health officials and AIDS activists are responding to the resurgent problem with renewed warnings of the dangers of unsafe sex - including graphic posters and street outreach.

A study released last year by the U.S. Centers for Disease Control and Prevention showed that 4 percent of gay and bisexual men between the ages of 23 and 29 in six major cities were becoming infected each year. The rate, however, was 14.7 percent among African-Americans.

In Baltimore, one of the cities under study, 15 percent of gay men in that age group were becoming infected. The rate was 27.1 percent among black gays.

The study may have given an inflated picture because researchers recruited men who frequented gay bars at night.

But researchers found that more than three-quarters of those infected with the AIDS virus were unaware of it. This suggests that many were unknowingly transmitting the virus and were not getting treated.

Last week, the United Nations AIDS agency reported that half of the 36 million people infected with HIV globally are women. The figure is driven largely by the epidemic in Africa.

Though women account for an increasing part of the epidemic in this country as well, gay men still account for the largest number of new infections.

In Maryland, drug addicts now account for half of new infections - surpassing gay men.

On Monday, Mayor Martin O'Malley declared a "state of emergency" in Baltimore's battle against AIDS. The declaration came after heavy lobbying by an expert panel, which accused the mayor and health department of exercising poor leadership on the issue.

The panel, convened last year by the City Council, said one serious problem was the large, if undocumented, number of African-American men who identify themselves as heterosexual but have sex with men. Many of the men are infecting their unsuspecting wives or girlfriends.

Dr. William Blattner, chief of AIDS epidemiology at the University of Maryland's Institute of Human Virology, said this group doesn't show up as gay in any of the statistical breakdowns.

"They're being counted somewhere else. They may be called heterosexual," said Blattner, a commission member. "This [trend] has been there for a while - it just hasn't been recognized."

Activist groups are reaching out to gays in various ways.

In Baltimore's Mount Vernon, an organization has dispatched teams of heterosexual, gay and transgender men (men living as women) to counsel gay prostitutes and their customers. Sometimes, they are able to refer the people to a city van that offers free testing.

Bonita Paschall, director of the Baltimore Prevention Coalition, said the customers who do not identify themselves as gay are likely to ignore traditional public health messages.

"The man who does not see himself as gay is not hearing the message," she said.

Dr. Liza Solomon, director of the Maryland AIDS Administration, said she is concerned that the recent epidemic of syphilis among gays in San Francisco and other West Coast cities might soon hit Maryland. Because it is spread by unprotected sex, syphilis is often a harbinger of AIDS.

"Even though we haven't had a resurgence of syphilis, we're getting a sense of behavioral changes" that could give rise to one here, she said.

Steven Gibson, director of Magnet, a gay men's health center set to open in San Francisco next year, said the number of new HIV infections among gay men in that city is thought to have more than doubled, from 500 to more than 1,000, from 1997 to 2001 - even while infections among other groups fell.

"California's epidemic continues really to be among gay men," he said. "I think it does need to be a call to action."

Last spring, a gay men's health project teamed with San Francisco's health department to sponsor a "Spring Cleaning" during which gay men were urged to get tested for HIV and other sexually transmitted diseases. In exchange, they received coupons for discounts from merchants - including a flower shop and a fetish store.

Gibson said that one hurdle in that city's fight against HIV is that about one-third of its gay men already are infected.

"Any time you have that much disease in a community, it takes a lot more effort to bring it back down because it's already so prevalent," he said.

Gibson says there is some truth to the suggestion that a generation of younger gay men simply "never got the message" about unsafe sex and the risks of AIDS, but he points to another problem: complacency.

"Early on in the epidemic, when people were getting infected and dying so quickly, there was a tremendous amount of fear," he said. "And you can't maintain that level of fear over 20 years."

In October, the STOP AIDS Project, a San Francisco nonprofit that focuses on AIDS prevention, launched an ad campaign to counter a perception among HIV-negative men that the disease isn't that devastating anymore or that living with it is easy - especially with all the advances in treatment.

The "HIV is No Picnic" campaign features four stark ads, which have been running in a local gay newspaper and on bus shelters. Each ad highlights a side effect of the disease or the drugs used to treat it.

Shana Krochmal, communications director for the STOP AIDS Project, said that a lot of gay men feel "really burned out" on the safe-sex message and that many don't understand the serious side effects of anti-HIV medications.

"The reality of it is, it's not easy, it's not simple and it's not something you want," she said.