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Oct 31, 2007

Dr. Frascino, I am writing in the hopes that you can clarify what I consider to be a massive misunderstanding taking place not only in the HIV at-risk community but in the health sector: What is the transmission rates in heterosexual contact, and what is the liklihood of HIV transmission in hetero sexual contact? In a recent post you seemed upset that people seemed to believe that hetero sex is low risk, yet CDC figures place the chance of transmission at .5 per 10,000 encounters for female to male. But yet another CDC report, the one linked here on this site, states that 15% of new HIV diagnosis in 2005 were from hetero sexual contact. That seems unreasonably high considering the low transmission rate. I work for a health district, and several of our employees feel that hetero sex is not much of a risk factor (if at all). I don't want to give the wrong information to my clients, but even I'm stymied by this apparent contradiction. The way I see it, there are a few explanations for the incongruence between estimated incidence and prevalence: 1. The .5 in 10,000 transmission possiblity rate is wrong 2. The 15% new infection statistic is wrong, or too generous. The data appears to be derived from partner elicitation and as such, people may simply not be reporting MSM or IDU behavior. 3. Both are correct, and people are having so much hetero sex that HIV is getting transmitted despite the low chance of acquiring HIV from a hetero encounter in a single exposure.

Please, there is a great deal of confusion regarding this matter. Set the record straight definitively.

-Stevie in Washington

Response from Dr. Frascino

Hello Stevie in Washington,

The "massive misunderstanding" is indeed frustrating and unfortunate. It stems from a basic lack of understanding about statistics and epidemiology. The take-home message that everyone should be expounding is: "The major route of HIV transmission worldwide is heterosexual sex." Period! This fact is undeniable and universally accepted by everyone the World Health Organization (WHO), CDC (Centers for Disease Control), UNAIDS (The Joint United Nations Programme on HIV/AIDS), etc. There should be absolutely no confusion or misunderstanding of this very basic fact. If we all could get that very basic message out to the at-risk population, HIV awareness and prevention efforts would take a quantum leap forward in dispelling the myth that "hetero sex is not much of a risk factor (if at all)!" Approximately two thirds of the over 40,000,000 HIV-infected people worldwide contracted the virus through heterosexual sex. How people could deny that fact is incomprehensible to me.

The confusion, I believe, stems from the fact that risk factors vary within and across populations. In many parts of the world, men who have sex with men, injection drug users and sex workers account for significant proportions of HIV infections. These variations have given some shortsighted folks a false sense of security, allowing them to foster the belief that HIV/AIDS is someone else's problem. That it's at best a distant threat and certainly not a clear and present danger. Nothing could be further from the truth. I find it sad and disconcerting that over 25 years into the pandemic and with over 25 million lives prematurely snuffed out by this scourge, so many people can still hold to such dangerous beliefs! It also reflects on what an abysmal failure our HIV/AIDS awareness and prevention efforts have been to date. (Thank you Dubya and your immoral abstinence-only science-phobic policies on sex education and STD prevention!)

My advice to you and others in the field is not be "stymied by apparent contradictions" in epidemiological statistics. When one really comprehends mathematical modeling and epidemiological statistics, the numbers really do all make sense. However, trying to educate the public at large about the differences between population surveys, incidence, prevalence and confounding variables is an unrealistic goal. We need to keep the message simple, clear, concise and consistent. For example, is unprotected heterosexual sex a risk? Yes, absolutely. It's by far the most common way people worldwide become HIV infected. What's the riskiest sexual activity? Unprotected anal sex (either hetero or MSM). This is due to many factors, including the fact there is more potential trauma to delicate rectal mucous membranes compared to vaginal mucous membranes during penetration.

If we can keep our messages at this level, I feel we'll indeed ultimately "sex the record straight" about sex (particularly about "straight sex").

Finally, for those shortsighted, self-centered individuals who only want to know about their heterosexual sex risk in their own very limited universe, I'll give you the facts for the percentage of adult AIDS cases by transmission category for California (by five-year intervals). (Note these are documented AIDS cases not estimated HIV infections.) Heterosexual sex accounted for 2% of AIDS cases in 1987. By 1992 it was 4%. By 1997 it increased to 9%. By 2002 it was 11%. And for 2005 the percentage had increased to 17%! The cumulative number for the entire epidemic (adult heterosexual transmission in California) is 20%. So the next time your coworkers spout off about low to no risk of hetero-sex, you should now be well prepared to knock some common sense reality into them!

Good luck.

Dr. Bob

Hepatitis B Vaccine and Hiv Antibodies. Donated $50.

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