In the summer of 1981 the eyes of many U.S. health researchers were focused on Los Angeles, where reports of five rare cases of Pneumocystis carinii pneumonia had turned out to be the beginning of the U.S. AIDS epidemic. This summer, health officials are again casting a worried glance toward Los Angeles and other Western communities, where two new mini epidemics'syphilis and drug-resistant staph infections'are unfolding. And concerns are mounting that the infections, both of which can be passed through unprotected sex, could signal a large-scale shift away from safer sex and possibly even foreshadow rises in HIV infection rates. 'We're very afraid that unprotected sex is returning to a pre-AIDS level,' says Bob Wood, director of the HIV control program for Seattle'King County, where syphilis infections are up dramatically among gay and bisexual men. 'That could be very bad news.' Fueling these worries is data emerging from organizations around the country documenting a rise in unprotected anal sex. San Francisco's Stop AIDS Project reports that its surveys of about 30,000 gay men conducted between 1994 and 2001 show that the incidence of both unprotected anal sex and unprotected anal sex with partners of unknown HIV status roughly doubled during the survey period. Since 1985, HIV antibody test recipients at Seattle clinics have reported a 25% increase in rates of unprotected sex. While taking sexual risks might seem surprising after 20-plus years of HIV prevention campaigns, David Evans, program director for the Stop AIDS Project, believes the behavior is not a new phenomenon. Unprotected sex'and sex with multiple and anonymous partners'has been on the rise since the early 1990s, he says: 'The risk pool was there just waiting for the introduction of something like syphilis to really take hold and spread.' And take hold it has. In Los Angeles County, syphilis rates among men who have sex with men soared 62% from 2001 to 2002. About 80% of all new infections in San Francisco are among gay and bisexual men. Syphilis cases in Oregon have hit a nine-year high, with more than twice the number of new infections in 2002 that there were in 2001. In Seattle'King County, syphilis cases today are being recorded at the same levels seen in the pre-AIDS era, with 95% of new infections occurring among men who have sex with men and 70% in HIV-positive men. As in Seattle, most new infections reported in San Francisco, Los Angeles, and other Western communities are among HIV-positive men. While that might suggest that infected men are putting their sex partners at risk for HIV infection, some health officials say it is more likely something they call 'serosorting''HIV-positive men who engage in unprotected sex only with other infected men. 'A lot of people have been pretty open about having sex with other positive guys, because they felt they weren't putting other people at risk,' Evans says. 'It's pretty much been going on since the beginning of the epidemic.' Serosorting could also be a factor in the recent reports of drug-resistant staph infections spreading particularly among HIV-positive gay and bisexual men, says Edwin Charlebois, an assistant professor of medicine at the University of California, San Francisco, and a member of the infection control team for San Francisco General Hospital. The infections, which typically manifest as painful, boil-like skin eruptions, were first recorded among gay and bisexual men in Los Angeles in the fall of 2002 and then quickly thereafter in San Francisco, Atlanta, Boston, Miami, and Washington, D.C. In some of the outbreaks, half or more of the cases are being identified among HIV-positive men. While staph is one of the most common causes of skin infections in the United States, the bacteria does not always result in painful skin sores, explains Scott Fridkin, a medical epidemiologist at the Centers for Disease Control and Prevention. About 25% to 30% of people at any one time carry the bacteria in colonies on their skin, particularly inside the nose and around the armpits and groin, but most never develop complications. However, there is a growing concern that the drug-resistant staph'technically labeled methicillin resistant Staphylococcus aureus, or MRSA'cropping up in gay communities may be more virulent than other strains of the bacteria and may cause skin infections more easily. People with impaired immune systems also may be more prone to acquiring it, leading to the high percentage of cases reported among HIV-positive men, speculates Nolan Lee, a medical epidemiologist at the Los Angeles County Department of Health Services. Lee is heading up a study on the local outbreak. 'It may just be a nastier bug than we're used to seeing,' adds Charlebois. Staph, unlike syphilis, can be transmitted easily, through shared clothing, shared drug paraphernalia, skin-to-skin contact, and even coming into contact with another person's sweat. But there are fears that sex'particularly having anonymous encounters and multiple partners'could be allowing the infection to move more quickly than expected through gay male circles, Charlebois says. Bathhouses and sex clubs also could be environments where the bacterium is readily spreading. Health experts are concerned too that visitors to cities with large gay populations, such as San Francisco and Los Angeles, or attendees of circuit party events'where drug use, anonymous sex, and seas of sweaty, shirtless men on packed dance floors are commonplace'could be picking up the staph infection and carrying it back to their hometowns. 'The potential is very, very real for widespread problems to develop,' warns Jerry Cheney, STD prevention education coordinator for New Mexico's health department. Ralph Hansen, a physician and infectious disease specialist at Beverly Hills'based Pacific Oaks Medical Group, one of the nation's largest practices devoted to HIV care, believes the real root of the problem with both the staph and syphilis infections is simply that gay men'young and old alike'have adopted a cavalier attitude toward multiple sex partners and unprotected sex. 'Everyone seems to be fucking out there, and people aren't using condoms,' he says. 'It's a level of carelessness that perhaps wasn't noted by me and my colleagues five or six years ago.' There are several possible contributing factors to this rise in condomless sex, explains Tony Mills, a Los Angeles physician with a large number of gay and HIV-positive patients. One is that because young gay men might never have known anyone who died of AIDS complications, they do not have firsthand motivation to practice safer sex. The advent of highly active antiretroviral therapy has also led many to view HIV as a manageable condition, like diabetes, that can be controlled for years, even decades, with medication. And the public face of the AIDS epidemic has changed to one of robust men and women leading healthy lives because of successful drug treatments. 'We don't see the people who are failing therapy and are in hospices or are homebound,' Mills says, 'so we forget.' Whatever the reasons, HIV experts and health care providers are disheartened by rising rates of unprotected sex and are bracing for another surge in the HIV epidemic. 'I'm very discouraged,' says Wood, who has known since 1985 that he is HIV-positive. 'I've been working on AIDS issues for the past 20 years, and I've put a lot of my patients and my friends in their graves. My guess is they're all turning over in the graves right now wondering what is going on. And I wonder, how come people didn't learn?'