HIV Epidemiology and Something Even Many Smart Medical Students Don't Know

June 4, 2011

Paul E. Sax, M.D.

Paul E. Sax, M.D., is director of the HIV Program and Division of Infectious Diseases at Brigham and Women's Hospital in Boston.

Periodically I like to give an informal quiz to the medical students about HIV epidemiology. It's a multiple choice question that goes something like this:

Based on the recent epidemiology of HIV in the United States, in what group are new cases of HIV infection rising the fastest?

  1. Men who have sex with men (MSM)
  2. Injection drug users (IDUs)
  3. Heterosexual women
  4. Some other group

(Correct answer: #1.)

HIV Epidemiology and Something Even Many Smart Medical Students Don't Know

Now these are smart kids. Many of them have done impressive things before starting med school, including a bunch who have even worked in the HIV field (especially global HIV). Yet despite these brains and experience, you'd be amazed how often they choose the wrong answer, most commonly choosing #3 (a group in whom incidence is essentially flat or declining) or #2 (injection drug use HIV in the USA is, thankfully, disappearing).

On the 30th Anniversary of the first report of what is now known as AIDS, the MMWR has released its latest HIV Surveillance report. And, as in pretty much every year for more than a decade, here are the facts:

Surveillance data show that the proportion of HIV diagnoses occurring in MSM continues to grow. HIV incidence among MSM has increased steadily since the early 1990s. In 2009, MSM accounted for 57% of all persons and 75% of men with a diagnosis of HIV infection... Syphilis and gonorrhea are endemic among MSM; outbreaks or hyperendemic sexually transmitted infections have been reported from many communities where HIV infection also is prevalent, further increasing the risk for acquiring and transmitting HIV.

I'm not sure why this isn't more widely known (certainly we HIV/ID specialists know it), but I have a theory. Sometimes a story has media "tickiness", and once it's out there, it's hard to get rid of it. When AIDS first hit, it was overwhelmingly a disease of MSM and IDUs; quickly it became apparent, however, that it was a sexually transmitted infection so that women were at risk too. This was a big media story -- famous Life Magazine cover shown above -- and somehow this has never disappeared.

It's kind of like, "tuberculosis is making a comeback in the USA" when, in fact, TB rates are historically low. The TB Comeback is just too sticky. Same thing with the generalized HIV epidemic in this country which, if you take a look at this incredibly cool map, has never happened.

Take home message: HIV prevention and testing efforts should be maximally deployed where the epidemic is still raging. Here in the USA, that means MSM and/or communities of color.

Paul Sax is Clinical Director of Infectious Diseases at Brigham and Women's Hospital. His blog HIV and ID Observations is part of Journal Watch, where he is Editor-in-Chief of Journal Watch AIDS Clinical Care.

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This article was provided by NEJM Journal Watch. NEJM Journal Watch is a publication of the Massachusetts Medical Society.

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