"The numbers are harrowing," Mike Shriver, Mayor Willie Brown's official adviser on AIDS and HIV policy, said Wednesday. "We aren't just getting one snapshot of one group of high risk people in one place. We have a constellation of data sets now all converging at higher incidence estimates."
The current rate of new infections with HIV, the virus that causes AIDS, among San Francisco gay men is 2.2 percent, up from 1.04 percent in 1997, according new estimates reached by city researchers and health experts. That translates into roughly 748 new infections projected for this year.
San Francisco's 2.2 percent incidence rate means that in any given year, 22 of every 1,000 gay men will contract HIV. A quarter of the city's estimated 46,800 gay men are HIV-positive. About 80 percent of HIV infections in the city are among gay men, an estimate based on several studies.
The infection rate for gay men who also inject intravenous drugs was estimated to have more than doubled to 4.6 percent, compared with 1.9 in 1997.
The estimates, based on four new studies, are both higher than preliminary figures San Francisco released last year and confirm fears that a new wave of the AIDS epidemic could be gaining steam.
Public health experts say the San Francisco data was a clear sign that after years of relative stability thanks to aggressive prevention programs, safer-sex publicity and new drug treatments, the gay community was dropping its guard against the HIV virus.
"Nobody likes to have to negotiate sex, and nobody likes to have to use condoms. People are going to drop those if they think they can," said Dr. Thomas Coates, director of the AIDS Research Institute at the University of California-San Francisco.
Coates said that, paradoxically, the successful new AIDS drug treatments were now believed to be one reason for the rising level of new infections.
The antiviral drugs are keeping HIV-positive individuals alive longer, making it possible for them to spread the virus to more people. In addition, the drugs first released in the mid-1990s have eased the horror of watching loved ones die a slow, agonizing death.
"There are people out there who have never seen anyone waste away from HIV," said James Columbo, a University of California, San Francisco counselor who works with men newly diagnosed with HIV. "That played a really huge role in motivating people to stay HIV-negative."
The trend may not be unique to San Francisco. Federal health officials say similar findings are beginning to surface in Seattle, Los Angeles, Miami and Chicago.
"This is a signal we should take very seriously. This is going to happen anywhere where chemical methods are introduced to control the virus hat are not perfect," Coates said.
San Francisco's initial projections of rising AIDS infection rates last year was the first to illustrate a direct link between new HIV infections and an increase in risky behavior among gay men that experts have tracked over the past five years.
San Francisco, known around the world as a gay capital, became one of the first centers of the AIDS epidemic in the early 1980s, when as many as half the gay men in the city were believed to be infected with HIV. Since 1981, more than 18,000 San Franciscans have died of AIDS.
Quick action by the city's gay community and public health officials also made San Francisco a model for the fight against AIDS, pushing new HIV infections down from an estimated high of 6,000 in 1982 to a fairly steady 500 per year throughout most of the 1990s.
Coates said San Francisco's role as a leading indicator of the next phase of the AIDS crisis would likely prove true this time around as well, noting that similar studies had started to track rising gay AIDS infection rates in Vancouver and Sydney, as well as rising rates of sexually transmitted diseases among gay men in London, Los Angeles and Seattle.