Determinants of Per-Coital-Act HIV-1 Infectivity Among African HIV-1–Serodiscordant Couples

Determinants of Per-Coital-Act HIV-1 Infectivity Among African HIV-1–Serodiscordant Couples

Determinants of Per-Coital-Act HIV-1 Infectivity Among African HIV-1–Serodiscordant Couples
To the Editor—Here, we discuss the residual risk of human immunodeficiency virus (HIV) transmission due to intermittent HIV shedding in semen during sustained long-term suppression of plasma viremia by antiretroviral therapy (ART) and the implications for serodiscordant heterosexual couples planning to conceive a child. In humans, these barriers are most commonly encountered at mucosal surfaces. Health-care providers have a unique opportunity to provide education and counseling to their patients (5,6). We searched PubMed and Embase databases for studies that established a relationship between VL and transmission risk, or primary infection and transmission risk, in serodiscordant couples. We assessed transmissions for linkage within the study partnership, based on HIV-1 sequencing. For most of these diseases, treatment of the patient’s sexual partner(s) is indicated. Studies consistently found that larger VLs lead to higher HIV transmission rates, but assumptions about the shape of this increase varied from exponential increase to saturation.

Of 3297 couples experiencing 86 linked HIV-1 transmissions, the unadjusted per-act risks of unprotected male-to-female (MTF) and female-to-male (FTM) transmission were 0.0019 (95% confidence interval [CI], .0010–.0037) and 0.0010 (95% CI, .00060–.0017), respectively. We recently demonstrated that high-level seminal CMV shedding is also associated with seminal shedding of HIV in MSM receiving ART [12]. The effects of semen on sexually transmitted infections (STIs) are complex and include characteristics that enhance and that block transmission. Patients seeking treatment or screening for a particular STD should be evaluated for all common STDs. How much primary infection contributes to overall transmission is a matter of debate [1], and estimates of the proportion of HIV transmission during the primary phase range from 2% to 90% [2]. Modifiable risk factors for HIV-1 transmission were plasma HIV-1 RNA level and condom use, and, in HIV-1–uninfected partners, herpes simplex virus 2 infection, genital ulcers, Trichomonas vaginalis, vaginitis or cervicitis, and male circumcision.

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