RichardKennaway comments on Open Thread, September, 2010-- part 2 - Less Wrong
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In my last post on Health Optimization, one commenter inadverntently brought up a topic which I find interesting, although it is highly contraversial - which is HIV/AIDS skepticism and rationality in science.
The particular part of that which I am interested in is proper levels of uncertainty and rationality errors in medical science.
I have some skepticism for the HIV/AIDS theory, perhaps on the level of say 20-30%. More concretely, I would roughly say I am only about 70% confident that HIV is the sole cause of AIDS, or 70% confident that the mainstream theory of HIV/AIDS is solid.
Most of that doubt comes from one particular flaw I in the current mainstream theory which I find particularly damning.
It is claimed that HIV is a sexually transmitted disease. However, the typical estimates of transmission rate are extremely low: 0.05% / 0.1% per insertive/receptive P/V sex act 0.065% / 0.5% per insertive/receptive P/A sex act
This data is from wikipedia - it lists a single paper as a source, but from what I recall this matches the official statistics from the CDC and what not.
For comparison, from the wikipedia entry on Gonorrhea, a conventional STD:
So it would appear that HIV is roughly 100-500 times less sexually transmittable than a conventional STD like gonorrhea.
So in my mind this makes it technically impossible for HIV to be an STD. These transmission rates are so astronomically low that for it to spread from one infected person to an uninfected partner would take years and years of unprotected sex.
If you plug that it to a simulation, it just never can spread - even if everyone was having unprotected sex with a random stranger every single day, it would still require an unrealistic initial foothold in the population by other means before it could ever spread sexually.
And of course, if you plug in actual realistic data about frequency of unprotected sexual intercourse with strangers, it's just completely impossible. Bogus. It doesn't work. It can not be an STD.
As gonorrhea (and I presume other STDs) are hundreds of times more transmissable than HIV, their low rates in the population place bounds on HIV's sexual transmission.
Finally, these rates of transmission are so low that one should question the uncertainty and issues with false positives - how accurate are these numbers really?
To say that this makes it not an STD is to misunderstand what an STD is.
An STD is not a disease whose transmission method is specialised to the act of copulation. It is merely a disease which is so difficult to transmit at all that only the most intimate of contact has any substantial chance of doing so. What is important about the sexual contact is not the sex, but the blood contact.
In HIV we have something that is so difficult to transmit that even conventional heterosexual intercourse has difficulty. Closer blood contact is required for a high chance of transmission, such as in anal intercourse (the intestinal lining is fragile and not adapted to contact with foreign bodies) or injection from infected needles. This has been known practically since the start from the epidemiology, before any pathogen was identified.
I'm not in quite agreement with both of your points. Yes of course HIV is transmissable only through blood, but I don't agree with that being a good criteria for use of the term "sexually transmitted", especially when other STD's such as gonorrhea are actually effective - they are measurably hundreds of times more sexually transmissable than HIV. This is probably due to both evolved mechanisms that those STDs have (such as ulceration formation) and overall low virality and transmissability of HIV.
So it is ingenous I think to change the categorization. HIV is clearly at an extremum, and perhaps would be better classified as a weakly transmissable blood borne disease, not an STD.
The evolutionary relevance is important here. How did this evolve?