A few interesting items have recently come up in the news and in the scientific literature about various methods for preventing the transmission of HIV.
First up is a study (1) published in PLoS Medicine this week that demonstrated the effectiveness of a combination of antiretroviral drugs in preventing viral transmission in a monkey model of HIV. The researchers demonstrated that taking the antiretroviral drug emtricitabine (FTC) orally could reduce the chance that a macaque would become infected. Adding tenofovir-disoproxil fumarate (TDF) increased protection, and injecting both drugs (instead of giving them orally) gave full protection (at least within the small population used in the study). This pre-exposure prophylaxis (PrEP) could offer a promising additional method to protect individuals against acquiring HIV, although–at least in the foreseeable future–it wouldn’t be particularly practical on a large scale. Another study (2) published last month in PLoS Medicine presented a mouse model for studying HIV transmission and also demonstrated the effectiveness of pre-exposure prophylaxis in these mice. Although macaques are genetically much more similar to humans, mice are much easier to work with under controlled conditions, so such a model is still very useful for studying pre-exposure prophylaxis.
Next, I was a little annoyed by a story in yesterday’s New York Times reporting that male circumcision may not be effective at preventing the transmission of HIV from males to females:
A number of studies showing that circumcision among men reduces their risk of infection from the AIDS virus has raised the hope that the procedure would also benefit their female sexual partners.
But the expectations were challenged Sunday by a new study showing that male circumcision conferred no indirect benefit to the female partners and, indeed, increased the risk if the couples resumed sex before the circumcision wound was fully healed, usually in about a month.
Fair enough, but the one-sentence description of the article that appeared in the daily headlines email was “Expectations that circumcision among men would reduce the risk of their female sexual partners becoming infected were refuted by a new study that proved it could immediately increase the risk” (emphasis added). I found this quite misleading, since it must be stressed that any temporary increase in HIV transmission was due to people having sex before the circumcision wounds had healed, against doctors’ orders. There’s nothing intrinsic about being circumcised that increases HIV transmission, and that’s not stressed at all in this article (particularly the point that this increase in transmission is totally irrelevant in regards to infant circumcision).
Issue number two with this press coverage was that, as the story even pointed out, “the findings did not reach statistical significance,” so one certainly can’t read much into these findings. In addition, the study (as far as I know) has not been published anywhere, which is another strike against it.
In the end, it remains to be rigorously demonstrated whether male circumcision affects disease transmission to females, although this study provides evidence that it doesn’t. Regardless, it is still well documented that male circumcision reduces the transmission of a whole host of diseases (including HIV) to males. In the grand scheme of things, I would imagine that cutting down on disease transmission in any one direction should decrease overall disease prevalence.
And, finally, at the very least we can all still agree that one of the most effective methods of preventing the spread of HIV is the use of condoms. Right? Well, not quite. In observance of Super Tuesday, here’s a gem from Republican frontrunner John McCain. From 17 March 2007:
Not that HIV/AIDS is an important issue or anything… but it appears that Republican presidential hopeful John McCain hasn’t been thinking much–or at all–about HIV prevention. The New York Times blog The Caucus reports that when asked about the subject at a recent campaign rally in Iowa, McCain looked completely stumped:
Did he support the distribution of taxpayer-subsidized condoms in Africa to fight the transmission of H.I.V.?
What followed was a long series of awkward pauses, glances up to the ceiling and the image of one of Mr. McCain’s aides, standing off to the back, urgently motioning his press secretary to come to Mr. McCain’s side.
The upshot was that Mr. McCain said he did not know this subject well, did not know his position on it, and relied on the advice of Senator Tom Coburn, a physician and Republican from Oklahoma.
His press secretary, Brian Jones, later reported that Mr. McCain had a record of voting against using government money to finance the distribution of condoms.
Happy voting, everyone!
- Garcia-Lerma, J.G., Otten, R.A., Qari, S.H., Jackson, E., Cong, M., Masciotra, S., Luo, W., Kim, C., Adams, D.R., Monsour, M., Lipscomb, J., Johnson, J.A., Delinsky, D., Schinazi, R.F., Janssen, R., Folks, T.M., Heneine, W. (2008). Prevention of Rectal SHIV Transmission in Macaques by Daily or Intermittent Prophylaxis with Emtricitabine and Tenofovir . PLoS Medicine, 5(2), e28. DOI: 10.1371/journal.pmed.0050028
- Denton, P.W., Estes, J.D., Sun, Z., Othieno, F.A., Wei, B.L., Wege, A.K., Powell, D.A., Payne, D., Haase, A.T., Garcia, J.V. (2008). Antiretroviral Pre-exposure Prophylaxis Prevents Vaginal Transmission of HIV-1 in Humanized BLT Mice. PLoS Medicine, 5(1), e16. DOI: 10.1371/journal.pmed.0050016