INHIBITORY FACTOR IN SALIVA
An article in the Journal of the American Dental Association (Vol. 118, June 1989) concludes that "saliva from healthy men, women, and children contained a factor that inhibits HIV-1 infection of lymphocytes [white blood cells]. This finding is consistent with the documented low risk of oral transmission of this virus and the infrequent isolation of HIV-1 from human oral fluids."
In their study, researchers took samples of saliva from uninfected people - nine women, nine men, and seven children - and from nine HIV-positive men. Each sample of saliva was incubated with concentrated HIV-1 for one hour, after which time lymphocytes were added to the saliva-virus mixture for another hour. The researchers then tested the mixtures three times, starting on the eighth day, looking for signs that the virus was replicating.
The saliva from all the women and children and from the majority of men completely protected the lymphocytes against infection with the virus. Three uninfected and two HIV-positive men had "substantial, partial inhibitory activity." Even when the saliva was diluted by a factor of 20 to 1, 50% of its inhibitory activity remained.
Among the authors' conclusions is a statement that has major implications for therapy: "The inhibitory activity displays an important characteristic of a pharmacological agent." This suggests that the as-yet unknown protective factor - probably a large protein molecule - may offer an important clue to the identification of a "natural, nontoxic [antiviral] product."
If identified, such a molecule could form the basis of an agent capable of protecting cells against HIV, and it would offer some insight into the mechanism by which the virus is neutralized, says Dr. Phillip Fox, chief of the clinical investigative section that conducted the research. To that end, four studies have been funded to continue the work.
"Based on what we've seen and the number of years of experience, there is enough background to see that [oral activity] isn't a route of transmission," Fox says. "To my mind it makes sense that this fluid - saliva - which definately contains the virus, is not transmitting it."
Because semen, saliva, and breast milk have all been shown to contain inconsistent, low levels of HIV, it seems sensible to look at the more clear-cut instance of uninfected babies being nursed by HIV-positive mothers, where the only risk factor was the baby's nursing.
Pediatric immunologist James Oleske of Newark, N.J., who was one of the first to identify AIDS in children, has criticized the CDC's recommentation that HIV-positive women not breast-feed their infants. "This is a typical overresponse," he says. "Yes, factors in saliva seem to inhibit HIV, which is just one more bit of evidence that you don't get AIDS through oral exposure very frequently."
Oleske knows of two European cases in which babies who became infected by transfusion after birth and were being breast-fed have infected their mothers. In both instances the children were teething and the mothers' nipples were cracked, creating a blood-blood rather than simply oral route of transmission.
DEFINING WHAT IS "LOW RISK"
On the basis of scientific evidence such as that presented above, some social-service organizations are now issuing guidelines that place oral sex in a low-risk category. One of these groups is the AIDS Commision of Toronto, Canada. Ed Johnson, director of education for the commission, says, "Because different organizations are saying different things - and there is often great discrepancy between them - we took every study available into consideration and, through the Canadian AIDS Social Coalition, came out with a statement that anal and oral sex cannot be considered of equal risk." Johnson's group then developed three catetories of risk, placing oral sex in the "minimal/theoretical" risk category. Unprotected anal or vaginal sex is in the high risk category; abstinence is listed as no risk.
Wayne Blankenship of the Tuscon AIDS Project, which is following Canada's lead, says that in the United States "We're so invested in having to see transmission in either black or white terms that we've painted ourselves into a corner. A real issue is that there is nothing positive said officially about any form of sex between men. This is a disservice to those trying to make rational choices."
While admitting that "no one would say that there's a 100% guarantee that oral sex won't transmit the virus," Blankenship says critics have sensationalized his group's guidelines as "advocating that people should be having oral sex without a condom. But that's not what our information is about. It's about the relative risk."
According to Kevin Armington, coordinatior of medical information for Gay Men's Health Crisis (GMHC) in New York City, the group's "safer sex" guidelines emphasize "safe, creative sexual activities." GMHC educational materials recommend either using a condom during oral sex or; if no condom is used, refraining from ejaculating in a partner's mouth. The group's concern over possible transmission through oral sex is based on several letters in the mid 1980s in the British medical journal The Lancet, which reported that a few people who claimed that they had participated in no other sexual activities than oral sex nonetheless became infected. Several I.V. drug-using lesbians have reportedly passed the virus to their partners through oral sex. This, GMHC argues, indicates that oral sex is not in a no-risk category.
Marcus Conant, a physician in San Francisco who sees a large population of AIDS patients, emphasizes, "You have to ask what is meant by 'low risk' - which does not mean 'no risk'. If you mean low, you have to decide what risks you are willing to take." Conant draws on the analogy of risks that people take every day: "On a California freeway you have a 1-in-4,000 chance of being killed; in a lightning storm, a 1-in-12,000 chance of being struck. A pregnant woman has about a 1-in-8,000 chance that her baby will have a severe birth defect. The risk of getting HIV from oral sex is clearly lower than 1 in 4,000 but whether it's lower than 1 in 12,000, I don't know.
"People are caught back in a 1983 frame of mind and haven't [stopped to think], Now anyone can get tested," Conant continues. "I wouldn't [advise people] to have rectal sex with anyone without a condom, but they might engage in something that has a low risk - if both were negative and being tested periodically."
PLAYING THE ODDS
In science, it's impossible to prove that something never happens. While Conant and other researchers suggest that the likelihood of becoming infected through oral sex is extremely small, there are no guarantees. It seems reasonable for people who are concerned about this to make sure that they and/or their partners are protected.
Toronto's Johnson says his group has been criticized for not pointing out that those who are already HIV-positive may risk contracting additional infections during unprotected oral sex. Conant, however, says this is farfetched. "They ride the subways and come in contact with people with a variety of infections every day," he says. "I'm not sure this is a valid issue."
GMHC educators express concern about possible unnoticed breaks in the mouth, such as bleeding gums, that would increase the risk during unprotected oral sex. But others point to the small number of AIDS cases that can be traced to oral contact and the emerging evidence of saliva's protective role.
It comes down to a gamble. If you decide to play the odds with becoming infected, you should remember that however long the odds may be, unprotected oral sex does sometimes transmit HIV.
Here's one result... I've put the relevant part in red:
