Mr. U, 22 years old and gay, had a maculopapular rash on his palms and soles. Eight weeks earlier, he had had a flulike illness that included fever to 102°F, sore throat, and muscle aches. His physician, who saw Mr. U a month before for a physical, diagnosed influenza. Three months ago, Mr. U engaged in unprotected receptive anal intercourse with a partner he was “sure” was HIV-negative. Mr. U’s rapid plasma reagin (RPR) test was positive at 1:128, and a rapid HIV test was reactive. Mr. U, who had tested negative for HIV six months earlier, cannot believe the results.

Despite widespread knowledge of HIV transmission routes, the incidence of new infections in the United States has remained steady at about 40,000 per year. The CDC estimates that more than 1 million Americans are now living with HIV or AIDS, but about 25% of those are unaware they’re infected.

The statistics are daunting, yet some significant successes have slowed the HIV epidemic. The blood supply is much safer than it once was, and mother-to-child transmission has fallen sharply with antiretroviral use during pregnancy and delivery.

The basic facts about HIV transmission have not changed, but new data have shed some light on this sensitive topic. Earlier this year at the Conference on Retroviruses and Opportunistic Infections (CROI) in Los Angeles, several pertinent studies on transmission were presented. Here’s what you should know to help curb transmission among your patients.

Abstinence-only approaches don’t work. In a session on the status of the U.S. HIV/AIDS epidemic, Harold Jaffe, MD, a former head of the CDC, discussed a not-yet-published review of behavioral modification studies employing abstinence-only approaches. None of the eight randomized studies demonstrated that encouraging abstinence alone caused a decrease in self-reported risk behaviors or incidence of pregnancy or sexually transmitted infections (STIs). Abstinence counseling definitely has a place in a comprehensive prevention education program, but it should not be used as a stand-alone strategy.

Condoms can help. Consistently and properly used, latex condoms profoundly decrease the risk of HIV transmission. However, condoms do not reliably prevent other STIs, e.g., those of herpes simplex virus (HSV) and human papillomavirus, or syphilis, all of which can be transmitted by skin-to-skin contact. Moreover, the presence of STIs like HSV and syphilis, even when subclinical, facilitates HIV transmission.

What about treating HSV-2? Two randomized, controlled trials discussed at CROI showed that treating HSV-2 with acyclovir lowered HIV viral load in serum and cervicovaginal fluid in women co-infected with HIV and HSV. Participants were not on highly active antiretroviral therapy. A third study showed that co-infected pregnant women who were shedding HSV-2 DNA in cervicovaginal fluid at the time of delivery transmitted HIV to their infants at a rate of 28.6% vs. 8.5% of women who were not shedding at the time of delivery.

Circumcision is helpful. We now have clear evidence that male circumcision decreases acquisition of HIV.1 These findings have prompted New York City to consider promoting circumcision as an HIV prevention strategy. One CDC survey hinted that circumcision (which would by no means eliminate the possibility of female-to-male transmission of HIV) would be acceptable to more than half of uncircumcised men if it would definitely decrease the chances of acquiring HIV.

Topical microbicides get a close look. Tenofovir, a nucleotide analog approved to treat HIV infection, is being studied as a topical microbicide. In one study of a gel containing tenofovir, researchers were able to protect six of nine rhesus macaques from rectal challenge with simian immunodeficiency virus2 (a frequent animal model for HIV). In contrast, four of four untreated controls and three of four macaques who received placebo gel seroconverted after the same exposure.

Further investigation is likely, and a multicenter study using single-dose tenofovir as pre-exposure prophylaxis is under way.3 One human study of cellulose sulfate, a topical spermicide, was terminated when it failed to prevent HIV transmission.

Post-exposure prophylaxis (PEP) reduces infection rate. PEP with antiretroviral drugs after occupational exposure has been shown to reduce the rate of infection by 81%. PEP is widely used following sexual exposure to HIV, although studies have not proven its efficacy to date.

Communication is key. We must continue to counsel patients on ways to avoid infection. Ask what your patients are doing sexually and whether they are using drugs in a way that exposes them to the blood of others. Sexually active patients should be screened for HSV infection and treated if necessary.

Also, primary HIV infection deserves a place on the differential list when patients present with flulike illnesses. Following infection, a majority of patients (50%-90%) experience a flulike illness characterized by, in decreasing frequency, fever, pharyngitis, maculopapular rash, arthralgias, myalgias, and headache. Symptoms usually occur within the first four to six weeks following infection. A polymerase chain reaction assay for HIV RNA is the best diagnostic test for acute HIV infection, since antibody tests may be negative at this stage.

Finally, don’t overlook as a tool the ability to diagnose those with unknown chronic HIV infection. Awareness of one’s HIV status is a powerful motivator to change behavior. The CDC now recommends that all patients aged 13-64 be tested routinely for HIV infection in all care settings, including primary care, using an “opt-out” model in which patients are informed that they will be tested unless they decline.

A variety of “rapid tests” that give results in 20-40 minutes are available for use with saliva or finger-stick blood tests. These tests have sensitivities approaching 100% but need a confirmatory Western blot assay. Patients are more likely to get their results when they are available on the same day.

Dr. Armington is an internist in New York City who specializes in caring for patients with HIV and AIDS.

References

1. Gray R, Kigozi G, Serwadda D, et al. Randomized trial of male circumcision for HIV prevention in Rakai, Uganda. Paper presented at: 14th Conference on Retroviruses and Opportunistic Infections; February 25-28, 2007; Los Angeles, Calif.

2. Cranage M, Sharpe S, Cope A, et al. Pre-exposure prophylaxis in macaques against rectal SIV challenge by mucosally applied PMPA: potential for complementation of microbicide and vaccination strategies. Paper presented at: 14th Conference on Retroviruses and Opportunistic Infections; February 25-28, 2007; Los Angeles, Calif.

3. Cardo DM, Culver DH, Ciesielski CA, et al. A case-control study of HIV seroconversion in health care workers after percutaneous exposure. N Engl J Med. 1997; 337:1485-1490.