It has been known for more than a decade that prevalent herpes simplex virus type 2 (HSV-2) increases risk for HIV acquisition. Now, a new meta-analysis published in The Lancet Infectious Diseases and funded by the World Health Organization quantifies for the first time the effects of exposure to HSV-2 on HIV acquisition.
Researchers from the United States, United Kingdom, and Switzerland reviewed 57 studies published between January 1, 2003, and May 25, 2017, that examined risk for HIV after exposure to HSV-2. The study authors examined the association between both prevalent and incident HSV-2 and risk for HIV acquisition. They also looked at the HIV acquisition risk among general populations vs risk among higher-risk populations — female sex workers, men who have sex with men, couples where one is infected with HIV, and attendees of sexually transmitted infection clinics.
The results of their analysis reconfirmed that HSV-2 infection strongly increases risk for HIV. In the general population, the adjusted relative risk for acquiring HIV in the presence of prevalent HSV-2 infection is 2.7 (95% CI, 2.2 to 3.4). In the high-risk population, the adjusted relative risk for acquiring HIV is 1.7 (95% CI, 1.4 to 2.1).
The risk for acquiring HIV is highest in the general population once infected with HSV-2. Genital ulcer severity, viral shedding, and inflammation are highest in new HSV-2 infection, and this finding strongly indicates that there is a direct biologic effect of HSV-2 infection on HIV.
These findings have important implications for management of patients with HSV-2, particularly those who are newly diagnosed, to prevent HIV infection, the researchers noted. New interventions that target HSV-2, such as vaccines or microbicides, could potentially help in the battle against HIV.
Looker KJ, Elmes JAR, Gottlieb SL, et al. Effect of HSV-2 infection on subsequent HIV acquisition: an updated systemic review and meta-analysis [published online August 23, 2017]. Lancet Infect Dis. X doi:10.1016/S1473-3099(17)30405-X