December 18, 2013
You're in a long-term, committed, monogamous relationship with a loving partner. You are not HIV infected, but your partner is. However, your partner is on stable antiretroviral therapy and has had a fully suppressed HIV viral load for several months.
Should the two of you still take measures (condoms, pre-exposure prophylaxis [PrEP], etc.) to reduce the risk of HIV transmission? Or is unprotected sex "safe enough"?
This is the question faced every day by thousands of couples in the U.S., and many thousands more throughout the world. It was also the issue vigorously debated by two prominent HIV clinician-researchers at a session entitled "Clinical Controversies" at IDWeek 2013. Roy "Trip" Gulick, M.D., took to the podium to argue the "pro" position in favor of continued prevention measures, while Paul Sax, M.D., was the standard-bearer for the "con" position.
"What does suppressed HIV RNA really mean?" Gulick asked rhetorically. "The fact is, it does not mean that there's no virus in the blood." On the contrary, Gulick said, research has shown that HIV is still potentially present in the blood plasma of patients with an "undetectable" viral load (the term typically applied to a viral load below the level of detection in blood using widely available assays, usually less than 50 copies/mL), and that in fact cases of transmission have indeed occurred in this setting.
Further, Gulick added, virus has also been found to potentially be present in the tissue, semen and cervicovaginal fluid of patients with an undetectable plasma viral load, suggesting a very real risk of transmission during activities that traditionally expose an individual to HIV. He cited two examples, in published research, of HIV transmission from an infected partner with an undetectable viral load to a previously uninfected partner. (One was a case report from 2008; the other was a case report from 2012 involving an elite HIV controller.)
It is these sorts of data that feed into an HIV risk calculation model that was published in The Lancet in 2008, which found a small per-sexual-act risk of HIV transmission from females to males (1 in 50,000), males to females (1 in 25,000) and males to males (1 in 2,500) -- risks that appear remote until one takes into account that the average couple engages in sexual intercourse 100 times per year, Gulick said.
In addition, HIV is not the only transmissible pathogen that couples should be concerned about, Gulick noted. Hepatitis C, gonorrhea, herpes simplex (and other herpes viruses), and human papillomavirus are just a few examples of additional, harmful microorganisms that can bring potentially severe consequences to the HIV-infected and uninfected partner alike -- and against which safer sex is the best protection.
Gulick also took a cynical, if realistic, approach on the nature of human fallibility and relationships. Citing results from HPTN 052 and the Partners PrEP studies in which extra-relationship transmission of HIV occurred despite partners saying they were in a "committed" union, Gulick questioned the value of a public health approach based on a trust between partners that was often broken. "Do we really want to advise our HIV positive patients to have unsafe sex?" he asked.
To which Sax responded: Absolutely.
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