This just in: Kissing can spread the virus that causes Kaposi's sarcoma. But is the news' bark worse than its bite?

Love may be a contact sport, but in the age of AIDS at least one of its basic plays -- kissing -- is mostly a case of "no harm, no foul." Or so we thought. But late last year University of Washington (UW) researchers reported that human herpes virus 8 (HHV-8), the cause of Kaposi's sarcoma (KS), can be spread via saliva. The risk comes, predictably enough, when there's a significant swap of spit -- a la "French," or "deep," kissing. Discovered in 1995 to be the cause of KS, a common HIV-related cancer, HHV-8 was long-suspected to be transmitted sexually -- but exactly how it was spread remained unclear. In 50 gay men (a mix of HIV positive and negative) who tested positive for HHV-8 and had not developed KS, the UW scientists found the virus in 30 percent of saliva samples but only one percent of genital or anal samples. The average HHV-8 viral load was two and a half times higher in saliva than it was in semen. In a separate study of 92 men who were HIV free, two factors -- a history of sex with a partner who had KS and deep kissing with an HIV-positive partner -- each increased the risk of HHV-8 infection.

HHV-8 may swim harmlessly in the blood of immune-healthy folks, as do so many of the other bugs that are responsible for AIDS' opportunistic infections. But estimates are that from one-third to one-half of all HIVers with HHV-8 will eventually develop KS, with its telltale purple lesions. So, despite dramatic reductions in KS during the HAART era (when the combos restored HIVers' immune function), HHV-8 transmission could spell danger down the road. This KS-causing herpes strain has been detected in between 10 and 20 percent of HIV-negative men, and between 30 and 55 percent of HIV-positive men. For couples, a major advance would be a test to show whether either partner has HHV-8, but researchers worry that current tests are not sensitive enough -- and could finger some HHV-8ers as negative.

Despite scientists' cautions that more research was needed, the media could not resist the hype: Pauk & co.'s December New England Journal of Medicine article, "Mucosal Shedding of Human Herpesvirus 8 in Men" had metamorphosed into alarmist "Kiss of Death"-type headlines (see "Mouth Off"). Parsing the paranoia, UW senior researcher John Pauk, MD, says, "We don't know the absolute risk. I think it's very likely our findings that HHV-8 can be transmitted through kissing will be confirmed, but we need to establish the actual risk. It may be difficult to transmit, and it may not." He adds that it would be a grave disservice if the sudden newsy focus on the KS-kissing connection distracts people from the need to practice safer sex, as a way to protect themselves against HIV, HHV-8 and other STDs. Pauk hopes that future studies will track serodiscordant HHV-8 partners to provide real-life answers to the many theoretical questions posed by this troubling study. Meanwhile, he says, "I can tell you that there's a potential risk from kissing, but I can't tell you how high it is."