Your daily dose of crazy nonsense about HIV

My current research is motivated by the fact that many people don’t realize that serodiscordance – sexual relationships where one partner is HIV-positive and the other is negative – is a possibility. The standard assumption is that transmission is very high-probability, so that discordance is rare; that assumption is false. While the misunderstanding is common worldwide, it has few practical consequences in the US, where people rarely know many folks with HIV. In Malawi, where the virus is common, though, people tend to realize that sometimes people don’t immediately contract the virus.

This has led to the promotion of a number of rumors about HIV transmission that involve certain acts being totally safe or certain people being immune. A really prominent one all over the Southern Region is that people with Type O blood are immune to HIV. Nothing could be further from the truth: ABO blood type has to do with your red blood cells, and HIV spreads through white blood cells. Moreover, the only study I know about HIV and blood type actually shows that people with type O blood are at more risk. This study is pretty badly designed, though. It doesn’t use random sampling, and blood type is correlated with other factors that impact HIV prevalence such as ethnic background. I’d venture that there’s really no relationship, but if anything there may be a small positive effect from type O blood – exactly the opposite of these rumors.

Now, the people who think this aren’t stupid – they’re operating off the information they have available, which doesn’t give them many ways of understanding serodiscordance. My understanding is that typical HIV prevention messages here are a stories about a single poor choice leading inevitably to death. If they’ve heard there are reasons why people don’t get HIV, this can help them sort out the conflict between the idea that HIV is transmitted for sure if you have unprotected sex, and the fact that some couples are discordant. So when I encounter this rumor, I always ask where people heard it. The most common place was through friends. In one case, though, a guy said he learned it in school. From whom? A local health official, there to teach them about HIV. Awesome.

As an added bonus, another man said that he had been taught in school, by a local health official, that HIV was not found in semen or vaginal fluid (and so unprotected sex is safe as long as there’s no bleeding). That is also wildly untrue.

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