#1: Herpes Simplex Virus 2 and HIV—What's the Connection?
Although international health organizations often focus on the nearly 37 million people worldwide who live with HIV, another sexually transmitted disease—herpes simplex 2 (HSV-2), the main cause of genital herpes, is a far more common condition. According to the World Health Organization, as of 2012, there were 417 million people globally between the ages of 15 and 49 with HSV-2, many of them, like most with HIV, reside in sub-Saharan Africa. And while HSV-2 on its own is not fatal, having the condition makes an individual more likely to contract HIV, just as having HIV raises a person’s risk of HSV-2.
This symbiosis and what it means for a vulnerable population was behind a British team’s effort to document the risk of HIV acquisition in people infected with HSV-2. Scientists at the University of Bristol and Imperial College London delved into multiple studies conducted up to 2017, mostly in Africa, that examined the connection between these 2 chronic infections. They found that individuals with HSV-2 had a decidedly higher risk of acquiring HIV than those without HSV-2. This risk was nearly tripled among the general population and doubled for people in high-risk categories, such as women engaged in sex work, men who frequent sex workers, and men who have sex with men. And when the data was analyzed to separate out individuals who had acquired HSV-2 after the study began versus those who had been infected with it earlier, the team found that the risk of contracting HIV was 5 times greater in the general population.
“The greater cofactor effect for incident HSV-2 infection than for prevalent HSV-2 infection might be because newly acquired HSV-2 infection is associated with an increased frequency and severity of genital ulceration, viral shedding, and inflammation in the genital tract, symptoms and manifestations that decrease with time after infection,” the authors wrote in the discussion section of their report. An HSV-2 infection that is active and symptomatic generates CD4-positive T cells. HIV targets these cells, and genital ulceration and viral shedding can enable HIV to break through the mucosal barrier in the genital area. Once infected with HIV, an individual with HSV-2 is likely to experience increased viral shedding that makes his or her infection more transmissible to others.
Read more about HSV-2 and HIV here
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