A wave of scary early February headlines about the dangers of oral sex has produced dismay and confusion among gay men and others nationwide. Surprisingly, one of those most dismayed was Frederick Hecht, MD, University of California San Francisco (UCSF) researcher and co-author of the study that generated all those headlines.

"I think our data are pretty similar to other data that has come out," Hecht told PlanetOut News. "We're a little surprised by the amount of attention it drew."

On Feb. 1 a team of researchers from UCSF and the federal Centers for Disease Control and Prevention (CDC) presented data at a San Francisco medical conference indicating that eight of 122 men newly infected with HIV almost certainly got infected via oral sex. Most experts agree with Hecht that this latest report did not significantly change what scientists have long understood: HIV can be transmitted via oral sex, but oral transmission is much more difficult and less common than transmission via anal or vaginal intercourse. And virtually all of the well-documented cases of oral transmission reported in the medical literature have involved ejaculation in the receptive partner's mouth.

But media coverage of the study generally ignored such subtleties. The Associated Press headlined its story, "AIDS Study: Danger of Oral Sex High." And the Los Angeles Times stated flatly, "At least 8 percent of all cases of HIV infection result from oral sex, according to researchers from the U.S. Centers for Disease Control and Prevention."

Beside getting the percentage wrong (eight out of 122 is 6.6 percent), the Times leaped far beyond what the researchers had actually said. While the published study abstract (available at http://www.retroconference.org/2000/abstracts/473.htm) states, "Despite lower transmission risk, oral sex may be an important mode of HIV transmission due to its frequency," the scientists never claimed that the percentages found in their relatively small sample could be generalized to the whole population.

What they did say, Hecht explained, is that gay men may have become a bit too sanguine about the safety of oral sex. "There is some risk," he said. "The basic message should be that if you have enough lower-risk behavior, it can be a more substantial mode through which people are infected. In earlier messages that oral sex is safer, the "er" has been dropped off and people have assumed that oral sex is safe."

While there is abundant evidence that receptive anal sex without a condom is the major route of sexual transmission among gay men, there have been numerous reports in the medical literature of HIV transmission via oral sex. In 1996, for example, researchers from the University of Washington reported that four out of 46 newly-infected patients they studied had no identifiable risk factors other than oral sex.

But it has been hard for researchers to develop a precise estimate of the risk involved. Kenneth Mayer, MD, director of medical research at Fenway Community Health in Boston, noted, "The trouble has been that a lot of people who have anal sex also have oral sex, so it's hard to know what the source of the infection is." Another complicating factor, he added, is that since HIV is fairly difficult to transmit, researchers "have to follow a huge number of people" to develop meaningful data.

The most recent and oft-quoted attempt to determine the risk levels of various sexual acts, a CDC study published last year in the American Journal of Epidemiology, estimated that unprotected receptive oral sex has a per-contact risk of .04 percent, or one in 2,500. This compared to .082, one in 122, for unprotected anal sex.

But that estimate came with a boatload of qualifications and limitations, starting with the fact that it assumed a partner of unknown serostatus. And though the data was based on a sample of 1,583 men followed for just over a year, there were only 49 seroconversions during the study. If just one or two misreported or misremembered their sexual activities or other HIV risks, it might skew the data substantially.

What frustrates many is that media headlines saying "oral sex is risky" give little useful guidance for individuals wanting to decrease their risk. Justin Hayford, a case manager at the AIDS Legal Council of Chicago, complained in a message posted on the Internet newsgroup sci.med.aids, "Is anyone ever going to bother to talk about HOW oral sex is risky and WHEN the risk arises? We need to know HOW and WHEN oral sex is risky, and to whom."

Actually, the existing data, including Hecht's study, does provide some guidance, but that information has often been left out of media coverage of the subject and is sometimes omitted or glossed over in the scientific reports themselves. One thing that is clear is that in the overwhelming majority of reported cases, HIV was passed from the insertive partner to the receptive one (that is, from the person being sucked to the one doing the sucking). There is just a tiny handful of reports of HIV being passed to the insertive partner, and the general consensus is that the risk to the suckee, while probably not zero, is extremely low.

In addition, ejaculation in the mouth appears to be an important factor. Mayer said flatly, "There's no convincing data that anybody's been infected by a partner that didn't ejaculate in their mouth." Still, he noted, "a few anecdotes" of such transmission have appeared as letters in medical journals, so the possibility can't be entirely ruled out.

Unfortunately, the medical literature often isn't as detailed as it might be. For example, the formal presentation by Hecht's group did not mention the issue of ejaculation, but in our interview he stated that seven out of the eight oral seroconverters acknowledged having had their partner ejaculate in their mouth. The 1999 CDC study mentioned above only looked at oral sex that included ejaculation, while some published studies haven't even asked the question.

Another presumed risk factor often unaddressed in the literature is the presence of sores or lesions in the receptive partner's mouth. The Seattle study, for instance, made no mention of this issue. It wasn't mentioned in the new UCSF/CDC report either, but Hecht said that "about half" of the eight seroconverters reported having mouth sores or some other dental condition that might facilitate entry of the virus. He said the researchers were still reviewing the data to confirm that figure.

Scientists face considerable difficulties in accumulating accurate data, starting with the fact that all of it depends on people's ability to remember and willingness to report the details of their sexual behavior. Still, Mayer said, "There are several of us who've said for years that we could have much better data" about oral sex than we do now. Mayer urged the CDC to fund a study looking at gay men who do not have anal sex at all as one way of obtaining clearer information.

In the meantime, the only risk-free option is to avoid unprotected oral sex entirely. Failing that, two precautions seem clearly advisable, most experts agree. First, avoid performing oral sex if you have any cuts or sores in your mouth or gums. Second, and perhaps most critical, is to agree with your partner at the outset that you will not ejaculate in each other's mouths. If that simple message could be given to gay men worldwide, Mayer said, "it would be a great public service."