Among diseases, HIV has a unique relationship with its risk factors. While pretty much any illness has a set of circumstances that make it more likely for a given individual to contract it—some diseases and individuals much more than others—HIV spent much of its named existence as something "of" certain populations. Inevitably then, risk factors comingled with identity, and stigma bloomed.
No doubt there are those remaining, even in 2014, whose whole fucked-up worldview gets a boost from HIV remaining the scourge of gay African-American men and intravenous drug users; for typical far-right narratives, those are two highly-encodable demographics. HIV's relationship to the world is changing, however, and quickly. Years of intensive outreach within high-risk populations is paying off, and the relative silence about HIV outside of those groups is having quite the opposite effect, while, at the same time, HIV itself is finding hetero-transmission help from its pal herpes.
In a study released on Friday, researchers at New York University's Center for Drug Use and HIV Research describe HIV infection rates among IV drug users in New York City falling to an epidemic-low of 10 percent, down from '90s highs approaching 50 percent. In the same time period, HIV rates among heterosexual, non-IV drug users, historically considered to be one of lowest risk pools (but still above not-at-all drug users, for a number of reasons), doubled, from 7 to 14 percent. According to researchers, what's behind the increase, in part, is the spread of HIV's viral ally, human herpesvirus 2 (genital herpes, HSV-2).
HIV transmission from heterosexual (vaginal) sex is, generally, less likely than other, more-discussed vectors. In fact, the likelihood of transmission from a positive male to a negative female partner is just eight in 10,000, while female to male transmission should occur in four out of 10,000 risk events. For receptive anal intercourse, that jumps to 138 transmissions out of 10,000, and needle sharing should yield 63 infections per 10,000 positive-to-negative shares. The thing about herpes, however, is that it makes transmission much, much more likely, and infection rates for HSV-2 in the United States sit at around one fifth of all adults, with the hardest-hit demographic being African-American women, with a near 50 percent infection rate.
"Heterosexual intercourse is usually not very efficient for transmitting HIV, but the efficiency of heterosexual transmission nearly triples in the presence of herpes simplex virus type 2," said Don Des Jarlais, the study's lead author, in a statement from NYU. There are a couple of reasons for the boost, according to the NIH. For one, genital herpes in outbreak mode causes lesions, open sores through which an HIV virus might find easy passge into a new recruit. Second, even if those lesions are healed and the herpes infection is considered latent, the CD4+ T cells that HIV needs to bind with and infect are known to hang around the sites of healed lesions, offering an alternative passage into the host.
Part of the answer, according to Jarlais and a growing chorus of public health experts, is what's known as "treatment as prevention." That is, we know well enough that antiretroviral therapy and the corresponding drop in viral load can torpedo the likelihood of HIV transmission. So if more HIV patients are getting proper treatment, then they're far less likely to spread the disease. What's more, administering antiretroviral therapy to uninfected individuals boosts those individuals' resistance to infection as well. Obviously that's not the most general solution, but it makes sense in known high-risk populations. Jarlais concludes optimistically: "If we can implement these programs on a large scale, we should be able to control sexual transmission of HIV in the city, and achieve the goal of an "End to the AIDS Epidemic."