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Clinical Care

What to Tell Your Patients About Safer Sex and Condom Use

How to Know What Patients Are at Risk, and How to Counsel Them

August 1996

Without a thorough risk assessment, many people at risk for HIV infection will go unrecognized by healthcare providers (1). The process of assessing a particular individual's risk of becoming infected with the human immunodeficiency virus gives both the care provider and the patient an opportunity to work together, to gauge the patient's degree of risk in a setting that is appropriate for this sort of intimate discussion.

If clinicians and other healthcare professionals are going to render accurate assessments of risk, they need accurate information on the risk of HIV transmission associated with various behaviors, sexual and non-sexual. And if those professionals are going to provide adequate and appropriate counseling to at-risk individuals, they need guidelines for that all-important aspect of HIV prevention.

Risks associated with specific sexual behaviors

Penile-anal sex with ejaculation puts the receptive partner, male or female, at the greatest risk of acquiring HIV from an infected partner (2). Estimates of the risk of infection for each such act range from 0.5% to 3% (3). This sexual behavior is considered highly risky even without ejaculation, because HIV is present in pre-ejaculatory fluid -- which your patients may refer to as "pre-cum."

Penile-anal intercourse is not as risky for the insertive partner (4), but there are enough reported cases of HIV infection where the sole risk factor was insertive penile-anal contact with an infected partner that this activity should also be considered highly risky (5).

During penile-vaginal intercourse, HIV can be transmitted from either partner to the other. Transmission from female to male is less efficient than from male to female (6), but menstruation may increase the risk that an HIV-positive female will infect a seronegative male (7). The risk of infection during one episode of unprotected penile-vaginal intercourse ranges from 1 in 500 to 1 in 5,000,000 (8).

Oral-genital intercourse -- more commonly called oral sex -- also poses a risk for HIV transmission (9). The risks associated with these activities vary with the role (insertive or receptive) taken by the individual. The receptive partner in fellatio is generally at higher risk than the one being fellated, but HIV transmission to the insertive partner has been documented. There are also case reports of HIV transmission from the receptive partner to the insertive partner during cunnilingus, but not the reverse. Because of the many variables involved, it is difficult to quantify the risk involved in these behaviors, but it is generally thought that transmission of HIV is at least ten times less likely to occur during oral sex than during penile-vaginal or penile-anal intercourse.

Kissing leads to contact with varying amounts of saliva. Although HIV has been isolated from saliva, the amount of virus present is known to be extremely low (10), and there is no evidence of anyone being infected with HIV through kissing.

Digital-anal, digital-vaginal, manual-anal, and manual-vaginal intercourse do not, as commonly defined, allow the exchange of body fluids needed for HIV transmission. In theory, if the skin of the inserted finger or hand has cuts or abrasions on it, there is a risk of HIV transmission from either partner.

A much more real risk, however, is that such activity will result in trauma of the lining of the vagina or rectum -- trauma that may increase the likelihood of HIV transmission during subsequent sexual activities. In any event, there are no recorded cases of HIV infection attributed to digital or manual intercourse.

Moreover, there is no evidence that the use of an insertive sexual device such as a dildo or butt-plug poses a risk of transmission, unless the device is shared by partners and proper disinfection techniques are ignored. In such instances, fluids from an HIV-infected partner can come into contact with the mucosa of an uninfected partner, and HIV transmission is possible. Here again it should be noted that insertive sexual devices can cause trauma to the vagina or anus, making transmission more likely during future sexual activities.

Although there have been no reported cases of HIV infection through oral-anal intercourse (4), patients should be cautioned that many microbes are transmitted by this route -- and these organisms can lead to life-threatening infections in severely immunocompromised individuals. For this reason, patients should be encouraged to use a latex barrier during oral-anal intercourse.

Mutual masturbation is considered a safe sexual activity. At least in theory, if the body fluid of an infected participant were to come into direct contact with a cut, tear, or other break in the skin of an uninfected participant, transmission could occur. In practice, however, there have been no reported cases of HIV transmission attributed to mutual masturbation.

The ingestion of feces (copraphagy) and drinking of urine also place those who engage in these activities at some theoretical risk of HIV infection, but there are no reported cases of transmission via these routes. Both of these activities can result in transmission of other infectious agents, however -- notably hepatitis A virus and cytomegalovirus -- and these pathogens can be life-threatening to immunocompromised persons. Any sadomasochistic behaviors that involve the use of shared insertive sexual devices, piercing of intact skin, or the drawing of blood also carry some risk, although transmission through these activities has not been documented.

Condom use

Due to widespread, alarmist reports on the failure rate of condoms, practitioners have sometimes been reluctant to encourage their seropositive and at-risk patients to use latex condoms during intercourse. In fact, the evidence strongly suggests that condoms are a highly effective barrier to HIV transmission, and health care providers should routinely recommend that their sexually-active patients use condoms whenever they have sexual relations.

Laboratory studies have shown that nonoxynol-9 effectively kills all of the HIV that is present in a condom, and condoms with this spermicide do not leak any viable virus. Moreover, even condoms that have not been treated with nonoxynol-9 do not permit the passage of HIV unless they break (11) -- a failure that occurs less than 1% of the time with proper use. Studies that simulated concentrations of virus at levels 100 million times higher than those found in semen showed that even at those extraordinary levels most condoms block the passage of HIV (12). Significantly, even those condoms that did leak reduced the risk of viral exposure 10,000-fold.

Condoms prevent transmission of HIV

Although condom failure rates are 3% to 12% when used to prevent pregnancy, these same numbers cannot be applied to the use of condoms in HIV prevention. In epidemiological terms, the absolute risk of acquiring HIV from the failure of a condom is much lower than the absolute risk of becoming pregnant through condom failure (12). This is because the likelihood that HIV will be transmitted through a single sexual act is much lower -- ranging from 0.2% for penile-vaginal intercourse to 3% for penile-anal intercourse (3, 8) -- than the risk that a single act of unprotected intercourse will lead to pregnancy.

In a study of heterosexual couples (in which one partner was infected with HIV and one was not), none of the 24 couples who consistently used condoms experienced seroconversion of the uninfected partner, whereas 6 of the 44 women whose regular sexual partners used condoms inconsistently seroconverted during the course of the study (7). A more recent study of condom use among couples found that none of the 124 partners who consistently used condoms seroconverted, compared with 12 infections among 121 partners who did not use condoms (13). This study involved thousands of sexual contacts without a single infection in the group that used condoms consistently.

Condoms are not completely effective in preventing the transmission of HIV infection, but they clearly reduce the risk of transmission for those who are sexually active. Health care providers can -- and should -- promote the use of condoms by making them available in public areas, such as waiting rooms, and more particularly in private areas, such as bathrooms and examination rooms, where patients can have access to condoms without embarrassment. Moreover, by providing condoms in this setting, the health care provider sends the patient a powerful message advocating the use of barrier protection (see the pull out and save feature in this issue, "How to Use Condoms Correctly").

Risks of selected nonsexual behaviors

Universal HIV antibody testing of the national blood supply has virtually eliminated transmission through blood products. Vertical transmission from mother to child is still a major health concern, as more women of childbearing age become infected with HIV. Vertical transmission is the major cause of pediatric HIV infection, with transmission rates varying from 13% to 30% (14). A pivotal ACTG study, completed in 1994, showed that administration of zidovudine to pregnant women reduced transmission rates by 67% (15), leading the C.D.C. to recommend HIV antibody testing for all pregnant women. Comprehensive prenatal care should also include an HIV risk assessment and the opportunity for confidential HIV testing.

Intravenous drug users risk HIV infection via contaminated needles and syringes. Risk reduction in this group begins with the recommendation that any shared injection equipment be cleaned with household bleach prior to use. Undiluted bleach has been shown to be effective in disinfecting needles and syringes against free HIV particles as well as HIV in cell culture (16), and HIV in whole blood is killed within 30 seconds of exposure to undiluted household bleach (17).

Significantly, undiluted bleach is the only household disinfectant that has been shown to kill HIV-infected cells. Ethanol, isopropyl alcohol, diluted bleach, and hydrogen peroxide are not as effective as bleach. In order to inactivate HIV, undiluted bleach must remain in contact with all contaminated parts of the needle and syringe for at least 30 seconds (18).

Several studies have examined the likelihood that HIV can be transmitted through human bites. Estimates of the risk of infection from a bite range from 0.1% to 0.4%. Several cases of transmission following a bite by an HIV-infected person have been reported, but in all but one of these cases other risk factors were present (19-21).

Office-based practitioners may well be asked about the danger of allowing HIV-infected children to attend daycare centers, nurseries, and primary schools. Bites from these children pose a risk to their peers so small that it cannot be calculated, and unwarranted fears about potential transmission of HIV infection through bites should not be used to exclude HIV-positive children from these settings.

Risk communication

Risk communication is an interactive process, a free exchange of information among individuals. It will be helpful if the clinician learns to view success in this arena in terms of how much sound information is made available to the patient -- and not in terms of what sort of decisions the patient ultimately makes. Success does not guarantee that the decisions the patient makes will maximize his health, only that the patient will understand what is known about the available options.

Candid, nonjudgmental communication of the risks inherent in various sexual and nonsexual activities can help the patient reduce those risks in gradual and appropriate ways -- producing behavior changes that can often be sustained, as opposed to abrupt behavior shifts that are too often abandoned.

HIV prevention activities can be incorporated into routine health screening in ways that add little additional time to the screening process (see "Screening Questions Used to Determine HIV Risk"). To facilitate this process, key screening questions can be included in the printed questionnaire that patients fill out on their first office or clinic visit. This form can be updated at each visit, and risk factors can be reassessed at that time.

For most patients, screening will consist of questions regarding sexual behaviors and drug use. These simple questions will often reveal if a patient is at risk for HIV infection. If any answer indicates that a patient may be at risk, that particular response should provoke further discussion -- and, where necessary, referral to an appropriate outside resource, advocacy group, or counseling service.


  1. Centers for Disease Control and Prevention. HIV prevention practices of primary-care physicians -- United States, 1992. MMWR 1994; 42: 988-92.

  2. Lifson A, O'Malley P, Hessol N, et al. HIV seroconversion in two homosexual men after receptive oral intercourse with ejaculation: implications for counseling concerning safe sexual practices. Am J Public Health 1990; 80: 1509-11.

  3. Caceres C, van Griensven G. Male homosexual transmission of HIV-1. AIDS 1994; 8: 1051-61.

  4. Palacio H. Safer sex. The AIDS Knowledge Base. Cohen PT, Sande M, Volberding P, eds. (New York: Little, Brown and Co., 1994), 10.6-1-10.6-12.

  5. Canadian AIDS Society. Safer sex guidelines: healthy sexuality and HIV, 1994.

  6. O'Brien T, Busch M, Donegan E, et al. Heterosexual transmission of human immunodeficiency virus type I from transfusion recipients to their sex partners. JAIDS 1994; 7: 705-10.

  7. European Study Group on Heterosexual Transmission of HIV. Comparison of female to male and male to female transmission of HIV in 563 couples. Br Med J 1992; 304: 809-13.

  8. Hearst N, Hulley S. Preventing the heterosexual spread of AIDS. JAIDS 1988; 16: 2428-32.

  9. Lane HC, Holmberg S, Jaffe H. Letter: HIV seroconversion and oral intercourse. Am J Public Health 1991; 81: 658.

  10. Levy J, Greenspan D. Letter: HIV in saliva. Lancet 1988; 2: 1248.

  11. Rietmeijer C, Krebs J, Feorino P, Judson F. Condoms as physical and chemical barriers against human immunodeficiency virus. JAMA 1988; 259; 1851-3.

  12. Novello A, Peterson H, Arrowsmith-Lowe JT, et al. From the Surgeon General, U.S. Public Health Service. JAMA 1993; 269: 2840.

  13. De Vincenzi I. A longitudinal study of human immunodeficiency virus transmission by heterosexual partners. N Engl J Med 1994; 331: 341-6.

  14. Panther L. A review of the 10th International Conference on AIDS. HIV and women: maternal-fetal transmission of HIV. Seattle Treatment Exchange Project Perspective, Fall 1994, 7-8.

  15. Conner E, Sperling R, Gerber R, et al. Reduction of maternal-infant transmission of human immunodeficiency virus type 1 with zidovudine treatment. N Engl J Med 1994; 331: 1173-80.

  16. Flynn N, Jain S, Keddie E, et al. In vitro activity of readily available household materials against HIV-1: Is bleach enough? JAIDS 1994; 7: 747-53.

  17. Shapshak P, McCoy C, Shah S, et al. Preliminary laboratory studies of inactivation of HIV-1 in needles and syringes containing infected blood using undiluted household bleach. JAIDS 1994; 7: 754-9.

  18. Shapshak P, McCoy C, Rivers J, et al. Letter: Inactivation of human immunodeficiency virus-1 at short time intervals using undiluted bleach. JAIDS 1993; 6: 218-9.

  19. Wahn V, Kramer H, Voit T, et al. Letter: Horizontal transmission of HIV infection between two siblings. Lancet 1986; 2: 694.

  20. Anonymous. Transmission of HIV by human bite. Lancet 1987; 2: 522.

  21. Vidmar L, Poljak M, Tomazic J, Seme K, Klavs I. Letter: Transmission of HIV-1 by human bite. Lancet 1996; 347: 1762-3.

Joshua Schechtel, M.D., is from the Center for AIDS Prevention Studies, San Francisco, CA.

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This article was provided by San Francisco General Hospital. It is a part of the publication HIV Newsline.
See Also
Quiz: Are You at Risk for HIV?
10 Common Fears About HIV Transmission
More Safer Sex Guides and Information