Quantified Risks of Gay Male Sex

post by pianoforte611 · 2014-08-18T23:55:11.577Z · score: 35 (39 votes) · LW · GW · Legacy · 40 comments

Contents

  HIV
  Gonorrhea
  Syphilis
  Clamydia
  HPV
  Case Study of HIV transmission; risks and strategies for reducing risk
  Risk reducing strategies
None
40 comments

If you are a gay male then you’ve probably worried at one point about sexually transmitted diseases. Indeed men who have sex with men have some of the highest prevalence of many of these diseases. And if you’re not a gay male, you’ve probably still thought about STDs at one point. But how much should you worry? There are many organizations and resources that will tell you to wear a condom, but very few will tell you the relative risks of wearing a condom vs not. I’d like to provide a concise summary of the risks associated with gay male sex and the extent to which these risks can be reduced. (See Mark Manson’s guide for a similar resources for heterosexual sex.). I will do so by first giving some information about each disease, including its prevalence among gay men. Most of this data will come from the US, but the US actually has an unusually high prevalence for many diseases. Certainly HIV is much less common in many parts of Europe. I will end with a case study of HIV, which will include an analysis of the probabilities of transmission broken down by the nature of sex act and a discussion of risk reduction techniques.

When dealing with risks associated with sex, there are few relevant parameters. The most common is the prevalence – the proportion of people in the population that have the disease. Since you can only get a disease from someone who has it, the prevalence is arguably the most important statistic. There are two more relevant statistics – the per act infectivity (the chance of contracting the disease after having sex once) and the per partner infectivity (the chance of contracting the disease after having sex with one partner for the duration of the relationship). As it turns out the latter two probabilities are very difficult to calculate. I only obtained those values for for HIV. It is especially difficult to determine per act risks for specific types of sex acts since many MSM engage in a variety of acts with multiple partners. Nevertheless estimates do exist and will explored in detail in the HIV case study section.

HIV

Prevalence: Between 13 - 28%. My guess is about 13%.

The most infamous of the STDs. There is no cure but it can be managed with anti-retroviral therapy. A commonly reported statistic is that 19% of MSM (men who have sex with men) in the US are HIV positive (1). For black MSM, this number was 28% and for white MSM this number was 16%. This is likely an overestimate, however, since the sample used was gay men who frequent bars and clubs. My estimate of 13% comes from CDC's total HIV prevalence in gay men of 590,000 (2) and their data suggesting that MSM comprise 2.9% of men in the US (3).

 

Gonorrhea

Prevalence: Between 9% and 15% in the US

This disease affects the throat and the genitals but it is treatable with antibiotics. The CDC estimates 15.5% prevalence (4). However, this is likely an overestimate since the sample used was gay men in health clinics. Another sample (in San Francisco health clinics) had a pharyngeal gonorrhea prevalence of 9% (5).

 

Syphilis

Prevalence: 0.825% in the US

 My estimate was calculated in the same manner as my estimate for HIV. I used the CDC's data (6). Syphilis is transmittable by oral and anal sex (7) and causes genital sores that may look harmless at first (8). Syphilis is curable with penicillin however the presence of sores increases the infectivity of HIV.

 

Herpes (HSV-1 and HSV-2)

Prevalence: HSV-2 - 18.4% (9); HSV-1 - ~75% based on Australian data  (10)

This disease is mostly asymptomatic and can be transmitted through oral or anal sex. Sometimes sores will appear and they will usually go away with time. For the same reason as syphilis, herpes can increase the chance of transmitting HIV. The estimate for HSV-1 is probably too high. Snowball sampling was used and most of the men recruited were heavily involved in organizations for gay men and were sexually active in the past 6 months. Also half of them reported unprotected anal sex in the past six months. The HSV-2 sample came from a random sample of US households (11).

 

Clamydia

Prevalence: Rectal - 0.5% - 2.3% ; Pharyngeal - 3.0 - 10.5% (12)

 Like herpes, it is often asymptomatic - perhaps as low as 10% of infected men report symptoms. It is curable with antibiotics.

 

HPV

Prevalence: 47.2% (13)

 This disease is incurable (though a vaccine exists for men and women) but usually asymptomatic. It is capable of causing cancers of the penis, throat and anus. Oddly there are no common tests for HPV in part because there are many strains (over 100) most of which are relatively harmless. Sometimes it goes away on its own (14). The prevalence rate was oddly difficult to find, the number I cited came from a sample of men from Brazil, Mexico and the US.

 

Case Study of HIV transmission; risks and strategies for reducing risk

 IMPORTANT: None of the following figures should be generalized to other diseases. Many of these numbers are not even the same order of magnitude as the numbers for other diseases. For example, HIV is especially difficult to transmit via oral sex, but Herpes can very easily be transmitted.

Unprotected Oral Sex per-act risk (with a positive partner or partner of unknown serostatus):

Non-zero but very small. Best guess .03% without condom (15)

 Unprotected Anal sex per-act risk (with positive partner): 

Receptive: 0.82% - 1.4% (16) (17)

                          Insertive Circumcised: 0.11% (18)

         Insertive Uncircumcised: 0.62% (18)

 Protected Anal sex per-act risk (with positive partner):  

  Estimates range from 2 times lower to twenty times lower (16)  (19) and the risk is highly dependent on the slippage and   breakage rate.


Contracting HIV from oral sex is very rare. In one study, 67 men reported performing oral sex on at least one HIV positive partner and none were infected (20). However, transmission is possible (15). Because instances of oral transmission of HIV are so rare, the risk is hard to calculate so should be taken with a grain of salt. The number cited was obtained from a group of individuals that were either HIV positive or high risk for HIV. The per act-risk with a positive partner is therefore probably somewhat higher.

 Note that different HIV positive men have different levels of infectivity hence the wide range of values for per-act probability of transmission. Some men with high viral loads (the amount of HIV in the blood) may have an infectivity of greater than 10% per unprotected anal sex act (17).

 

Risk reducing strategies

 Choosing sex acts that have a lower transmission rate (oral sex, protected insertive anal sex, non-insertive) is one way to reduce risk. Monogamy, testing, antiretroviral therapy, PEP and PrEP are five other ways.

 

Testing Your partner/ Monogamy

 If your partner tests negative then they are very unlikely to have HIV. There is a 0.047% chance of being HIV positive if they tested negative using a blood test and a 0.29% chance of being HIV positive if they tested negative using an oral test. If they did further tests then the chance is even lower. (See the section after the next paragraph for how these numbers were calculated).

 So if your partner tests negative, the real danger is not the test giving an incorrect result. The danger is that your partner was exposed to HIV before the test, but his body had not started to make antibodies yet. Since this can take weeks or months, it is possible for your partner who tested negative to still have HIV even if you are both completely monogamous.

 ____

For tests, the sensitivity - the probability that an HIV positive person will test positive - is 99.68% for blood tests (21), 98.03% with oral tests. The specificity - the probability that an HIV negative person will test negative - is 99.74% for oral tests and 99.91% for blood tests. Hence the probability that a person who tested negative will actually be positive is:

 P(Positive | tested negative) = P(Positive)*(1-sensitivity)/(P(Negative)*specificity + P(Positive)*(1-sensitivity)) = 0.047% for blood test, 0.29% for oral test

 Where P(Positive) = Prevalence of HIV, I estimated this to be 13%.

 However, according to a writer for About.com (22) - a doctor who works with HIV - there are often multiple tests which drive the sensitivity up to 99.997%.

 

Home Testing

Oraquick is an HIV test that you can purchase online and do yourself at home. It costs $39.99 for one kit. The sensitivity is 93.64%, the specificity is 99.87% (23). The probability that someone who tested negative will actually be HIV positive is 0.94%. - assuming a 13% prevalence for HIV. The same danger mentioned above applies - if the infection occurred recently the test would not detect it.

 

 Anti-Retroviral therapy

 Highly active anti-retroviral therapy (HAART), when successful, can reduce the viral load – the amount of HIV in the blood - to low or undetectable levels. Baggaley et. al (17) reports that in heterosexual couples, there have been some models relating viral load to infectivity. She applies these models to MSM and reports that the per-act risk for unprotected anal sex with a positive partner should be 0.061%. However, she notes that different models produce very different results thus this number should be taken with a grain of salt.

 

 Post-Exposure Prophylaxis (PEP)

 A last resort if you think you were exposed to HIV is to undergo post-exposure prophylaxis within 72 hours. Antiretroviral drugs are taken for about a month in the hopes of preventing the HIV from infecting any cells. In one case controlled study some health care workers who were exposed to HIV were given PEP and some were not, (this was not under the control of the experimenters). Workers that contracted HIV were less likely to have been given PEP with an odds ratio of 0.19 (24). I don’t know whether PEP is equally effective at mitigating risk from other sources of exposure.

 

 Pre-Exposure Prophylaxis (PrEP)

 This is a relatively new risk reduction strategy. Instead of taking anti-retroviral drugs after exposure, you take anti-retroviral drugs every day in order to prevent HIV infection. I could not find a per-act risk, but in a randomized controlled trial, MSM who took PrEP were less likely to become infected with HIV than men who did not (relative reduction  - 41%). The average number of sex partners was 18. For men who were more consistent and had a 90% adherence rate, the relative reduction was better - 73%. (25) (26).

1: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5937a2.htm?s_cid=mm5937a2_w

2: http://www.cdc.gov/hiv/statistics/basics/ataglance.html

3: http://www.cdc.gov/nchs/data/ad/ad362.pdf

4: http://www.cdc.gov/std/stats10/msm.htm

5: http://cid.oxfordjournals.org/content/41/1/67.short

6: http://www.cdc.gov/std/syphilis/STDFact-MSM-Syphilis.htm

7: http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5341a2.htm

8: http://www.cdc.gov/std/syphilis/stdfact-syphilis.htm

9: http://journals.lww.com/stdjournal/Abstract/2010/06000/Men_Who_Have_Sex_With_Men_in_the_United_States_.13.aspx

10: http://jid.oxfordjournals.org/content/194/5/561.full

11: http://www.nber.org/nhanes/nhanes-III/docs/nchs/manuals/planop.pdf

12: http://www.cdc.gov/std/chlamydia/STDFact-Chlamydia-detailed.htm

13: http://jid.oxfordjournals.org/content/203/1/49.short

14: http://www.cdc.gov/std/hpv/stdfact-hpv-and-men.htm

15: http://journals.lww.com/aidsonline/pages/articleviewer.aspx?year=1998&issue=16000&article=00004&type=fulltext#P80

16: http://aje.oxfordjournals.org/content/150/3/306.short

17: http://ije.oxfordjournals.org/content/early/2010/04/20/ije.dyq057.full

18: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2852627/

19:

http://journals.lww.com/stdjournal/Fulltext/2002/01000/Reducing_the_Risk_of_Sexual_HIV_Transmission_.7.aspx

20:

http://journals.lww.com/aidsonline/Fulltext/2002/11220/Risk_of_HIV_infection_attributable_to_oral_sex.22.aspx

21: http://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2811%2970368-1/abstract

22:

http://aids.about.com/od/hivpreventionquestions/f/How-Often-Do-False-Positive-And-False-Negative-Hiv-Test-Results-Occur.htm

23: http://www.ncbi.nlm.nih.gov/pubmed/18824617

24: http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD002835.pub3/abstract

25: http://www.nejm.org/doi/full/10.1056/Nejmoa1011205#t=articleResults

26: http://www.cmaj.ca/content/184/10/1153.short

40 comments

Comments sorted by top scores.

comment by Antisuji · 2014-08-19T05:19:01.778Z · score: 25 (25 votes) · LW · GW

While it's probably justified to correct for the sampling bias in prevalence statistics, it's worth pointing out that sexual partners are not sampled uniformly: the prevalence of a given STD will potentially be higher in the population of likely partners than in the general population.

comment by cousin_it · 2014-08-19T07:43:04.558Z · score: 15 (15 votes) · LW · GW

That's a good point, and probably applies to Mark Manson's guide too. It's similar to the well-known point that your friends are probably more popular than you are, because popular people have more friends.

comment by Alexandros · 2014-08-19T14:28:13.707Z · score: 7 (7 votes) · LW · GW

and of course this is another case of 'just because you hired the top 1% of the CVs you got, doesn't mean that those you hired are in the top 1% of programmers'. Less good programmers are more often looking for a job.

Is there a name for this pattern?

comment by James_Miller · 2014-08-19T16:25:30.799Z · score: 11 (11 votes) · LW · GW

Adverse selection.

comment by cousin_it · 2014-08-19T15:17:25.165Z · score: 0 (0 votes) · LW · GW

I think it's called "selection bias", though most people don't realize just how pervasive it is. Maybe we need subcategories. Another example is that the the neighboring lane in a traffic jam often moves faster than the lane you're in, because higher speed => larger gaps between cars => fewer cars => higher chance of finding yourself in the slow lane. (I have no idea if that reasoning is correct, but it sounds fun!)

comment by James_Miller · 2014-08-19T00:43:35.187Z · score: 13 (13 votes) · LW · GW

While teaching a game theory class at Smith College I used an example that made mention of how blood banks didn't want donations from gay men. A student asked me why blood banks would do this and I said it was probably due to not being able to completely tell from screening if a donor has AIDS. My students then actually began debating among themselves whether gay men were more likely to have AIDS than heterosexual men were.

comment by bramflakes · 2014-08-20T13:04:29.398Z · score: 22 (22 votes) · LW · GW

I once debated with myself whether I should donate blood given that I'd had sex with men before, but whom I was sure were HIV-negative. I did a quick Fermi estimate looking at the amount of contaminated blood samples the blood bank could expect nationally, first with only heterosexual donors, and then with heterosexual + homosexual donors, given that each blood sample underwent the most accurate HIV tests. The results were pretty staggering (order of magnitude difference).

That convinced me that the proscription was there for a very good reason and that I shouldn't violate it.

comment by ShardPhoenix · 2014-08-19T08:45:56.683Z · score: 12 (12 votes) · LW · GW

Yeah, the propaganda on this issue seems to have been quite effective since before reading this I had no idea the problem was (still) so severe.

comment by Letharis · 2014-08-20T01:13:07.107Z · score: 2 (2 votes) · LW · GW

While I recognize the true HIV prevalence is probably higher than most people would guess, what propaganda are you referring to?

comment by ShardPhoenix · 2014-08-20T04:37:17.321Z · score: 8 (8 votes) · LW · GW

I was young in the 80's, but my impression is that HIV/AIDS was considered a pretty gay-specific thing at first. Later there was more media pushing the idea that it can affect anyone - for example, one of my schools had a straight woman with HIV visit to tell us about it. While this was presumably well-meaning and may have even had good effects in terms of encouraging safety, it did lead me to a quite skewed perspective of the relative risks (I was still aware that it was more prevalent in gays, but not by how much).

comment by pianoforte611 · 2014-08-21T00:22:23.401Z · score: 8 (10 votes) · LW · GW

"HIV can affect anyone" is far better than "HIV is a gay thing" along several criteria.*

One: factual - it can indeed affect anyone. And the difference in prevalence varies form country to country. In parts of Southern Africa the prevalence is about the same as the general population.

Two: Instrumental. If those involved in public health used HIV as leverage to get everyone to wear condoms more often, then I applaud them. Many lives were saved, and many infections prevented.

Three: Political. I'd be very curious to know what proportion of people reporting that HIV affect gay men more are doing so out of genuine concern rather than as code for "Those gays are dirty and disgusting and deserve to die/be ridiculed".

  • "Some groups are at higher risk for HIV than others, and the transmission rates depend on the nature of the sex act" is the most correct, but it is unwieldy for a public health effort.
comment by Azathoth123 · 2014-08-22T08:39:13.965Z · score: -4 (8 votes) · LW · GW

it can indeed affect anyone. And the difference in prevalence varies form country to country. In parts of Southern Africa the prevalence is about the same as the general population.

Supposedly. Except, for some reason it doesn't appear to be heterosexually transmitted in western countries. The two most plausible explanations I've seen for this phenomenon are that either "AIDS" is massively over-diagnosed in in Southern Africa or that it is primarily transmitted by uncleaned syringes. Either way the "HIV can affect everyone" lie is leading a major misallocation of resources in Southern Africa that is likely leading to many deaths.

Instrumental. If those involved in public health used HIV as leverage to get everyone to wear condoms more often, then I applaud them. Many lives were saved, and many infections prevented.

Really? This seems more like a misallocation of resources to me.

Political. I'd be very curious to know what proportion of people reporting that HIV affect gay men more are doing so out of genuine concern rather than as code for "Those gays are dirty and disgusting and deserve to die/be ridiculed".

How about looking that the effect of telling the truth versus lying about the subject rather than the supposed motives of people for doing so.

comment by pianoforte611 · 2014-08-22T12:23:47.555Z · score: 6 (6 votes) · LW · GW

it doesn't appear to be heterosexually transmitted in western countries

http://www.sciencedirect.com/science/article/pii/S1473309909700210

comment by Azathoth123 · 2014-08-23T03:19:13.710Z · score: -2 (6 votes) · LW · GW

And yet, as you yourself pointed out, (at least in western countries) its prevalence among heterosexuals is much less than its prevalence among homosexuals.

comment by satt · 2014-08-24T06:16:05.711Z · score: 5 (5 votes) · LW · GW

Which is a consequence of HIV being harder to transmit through heterosexual sex. Which does not automatically imply HIV is impossible to transmit through heterosexual sex.

comment by Azathoth123 · 2014-08-24T06:19:43.740Z · score: -1 (5 votes) · LW · GW

That still doesn't explain how HIV spread as much as it did in Southern Africa given how hard it is to transmit heterosexually.

comment by satt · 2014-08-24T06:35:33.015Z · score: 4 (4 votes) · LW · GW

Epidemiologists currently reckon that's mainly down to Southern Africans having multiple concurrent partnerships and low male circumcision rates. (Other factors have likely played a role as well, like South Africa's recent bout of officially-sanctioned HIV/AIDS denialism, and the potentially higher transmissivity of the HIV-1 subtype prevailing in Southern Africa.)

comment by Azathoth123 · 2014-08-25T02:13:02.702Z · score: -1 (5 votes) · LW · GW

Southern Africans having multiple concurrent partnerships and low male circumcision rates.

Europe has an even lower circumcision rate.

the potentially higher transmissivity of the HIV-1 subtype prevailing in Southern Africa.

When I first herd this theory ~15 years ago it was accompanied by a prediction that the HIV-1 subtype would break into the western heterosexual population real soon now. Since that has failed to happen, I'm dubious about this theory.

comment by satt · 2014-08-25T13:04:44.187Z · score: 4 (4 votes) · LW · GW

Southern Africans having multiple concurrent partnerships and low male circumcision rates.

Europe has an even lower circumcision rate.

Pay attention to the word "and" in what you quoted, it is actually quite important. The Southern African Journal of HIV Medicine article I linked explicitly addressed Europe's lower circumcision rate:

The now conclusive body of epidemiological and biological evidence confirming the strong association between lack of male circumcision and HIV10-15 is increasingly understood to explain much of the roughly fivefold difference in HIV rates between southern and western Africa7,16 [...] However, this key driver does not explain why HIV has spread so much more extensively in southern Africa than in India or in Europe, where circumcision is similarly uncommon. Although sexual cultures do vary from region to region,20 these differences have not been studied in sufficient depth and their significance is not so obvious. [...]

Of increasing interest to epidemiologists is the observation that in Africa men and women often have more than one – typically two or perhaps three – concurrent partnerships that can overlap for months or years. [...] This pattern of concurrent partnerships differs markedly from that of the pattern of serial monogamy more common in the West – i.e. the tendency to have one relatively long-term (a few months or longer) partner after another – or the more ‘one-off’ casual and commercial sexual encounters that occur everywhere.

It is the conjunction of low male circumcision rates and multiple concurrent partnerships which explains HIV's strong showing in Southern Africa.

the potentially higher transmissivity of the HIV-1 subtype prevailing in Southern Africa.

When I first herd this theory ~15 years ago it was accompanied by a prediction that the HIV-1 subtype would break into the western heterosexual population real soon now. Since that has failed to happen, I'm dubious about this theory.

I don't give that point any more weight than the last time you raised it (which I can't link because the relevant post got deleted). Now, as then, you haven't cited any specific person or authority who's supposed to have made this prediction, and I still don't see why the failure of that prediction would be strong evidence against the hypothesis that HIV-1 group M subtype C likely has a higher transmissivity than HIV-1 group M subtype B. Non-zero evidence? Yes. Decisive evidence? No.

comment by Azathoth123 · 2014-08-26T01:06:46.490Z · score: -1 (5 votes) · LW · GW

I don't give that point any more weight than the last time you raised it (which I can't link because the relevant post got deleted). Now, as then, you haven't cited any specific person or authority who's supposed to have made this prediction, and I still don't see why the failure of that prediction would be strong evidence against the hypothesis that HIV-1 group M subtype C likely has a higher transmissivity than HIV-1 group M subtype B.

So why hasn't HIV-1 group M subtype C spread out of Southern Africa?

comment by satt · 2014-08-27T22:37:07.673Z · score: 3 (3 votes) · LW · GW

So why hasn't HIV-1 group M subtype C spread out of Southern Africa?

That question assumes a false premise. HIV-1 group M subtype C has spread out of Southern Africa.

Perhaps what you were trying to ask was why subtype C hasn't spread as aggressively as you personally expect beyond Southern Africa, though the information I gave two comments ago suffices to answer that question. Still, I will build on that information to spell this out.

The transmissibility of an HIV subtype is not the only factor determining how, and how far, that subtype spreads; behavioural differences between populations also matter. Southern African populations more often engage in non-circumcision and multiple concurrent partnerships than people elsewhere, and that combination of behaviours is the most likely reason why subtype C hasn't run riot among heterosexuals outside of Southern Africa (and Ethiopia & India).

If I leave things there, I suspect, I can look forward to a follow-up attempt at a dubious gotcha question along the lines of "So why bring up the transmissibility differences in the first place?". Because the fact remains that relative transmissibility is probably a factor in explaining why subtypes B & C have different spatial distributions. I had thought it clear that I was invoking relative transmissibility as merely a probable secondary factor, since I mentioned it parenthetically and wrote it "likely played a role", not that it was a sufficient, primary explanation in its own right.

comment by Azathoth123 · 2014-08-29T02:17:56.374Z · score: -1 (3 votes) · LW · GW

Southern African populations more often engage in non-circumcision and multiple concurrent partnerships than people elsewhere, and that combination of behaviours is the most likely reason why subtype C hasn't run riot among heterosexuals outside of Southern Africa (and Ethiopia & India).

What about western groups that have many sexual partners, e.g., the swinger and polyamory communities?

comment by satt · 2014-08-30T15:32:28.759Z · score: 2 (4 votes) · LW · GW

What about western groups that have many sexual partners, e.g., the swinger and polyamory communities?

Your question blurs the distinction between promiscuity and multiple concurrent partnerships — I assume that was an accident.

Which precise question are you asking? Are you asking why Western groups with MCPs and low circumcision rates don't have (much) subtype C? If so, I'd like some specific evidence that they don't — it's a good idea to establish a phenomenon occurs before trying to explain it, and I'm having trouble finding systematic evidence on the HIV subtypes found among Western polyamorous people & swingers. If your question is about something subtly different (e.g. if you're asking about HIV in general among those groups, not subtype C in particular), please clarify.

comment by Azathoth123 · 2014-08-30T17:26:18.971Z · score: -1 (3 votes) · LW · GW

Your question blurs the distinction between promiscuity and multiple concurrent partnerships

Which are?

If your question is about something subtly different (e.g. if you're asking about HIV in general among those groups, not subtype C in particular), please clarify.

Your theory predicts that promiscuous heterosexual westerners should be getting HIV at rates similar to Southern Africa. Near as I can tell this is not the case.

comment by satt · 2014-08-30T18:23:23.952Z · score: 3 (5 votes) · LW · GW

Which are?

Which is that one can have many sexual partners over some time period (promiscuity) without having multiple sexual partners simultaneously (concurrency), and one can have multiple sexual partners over some time period (concurrency) without having many (promiscuity).

Suppose Person A abstains from sex through the even months of each year, but in every other month (i.e. January, March, and so on) they have sex with one (& only one) new person. (So for example in January 2006 they have sex with a first person; in February 2006 they have no sex; in March 2006 they have sex with a second person; in April 2006, no sex; in May 2006, sex with a third person, and so on.) In the course of 50 sexually active years, then, they have 300 different sexual partners.

Suppose person B has weekly sex with 2 other people for 5 years, then weekly sex with 2 completely different people for the next 5 years, then weekly sex with 2 more completely different people for the 5 years after that, and so on. In the course of 50 sexually active years, they have only 20 different sexual partners.

Person B is liable to be a more efficacious transmitter of HIV than person A, despite person A being far more promiscuous.

Your theory predicts that promiscuous heterosexual westerners should be getting HIV at rates similar to Southern Africa. Near as I can tell this is not the case.

One, you are still conflating promiscuity and MCPs.

Two, do uncircumcized (if male) Western heterosexuals with MCPs get HIV at rates substantially below Southern Africa? Taking the 2011 statistics on Southern Africans living with HIV from Wikipedia's table, summing them, and dividing by the total population of those countries, I get 8.7%. This is high by general Western standards, but it's not obvious to me that HIV prevalence is lower among the unusual subset of Western heterosexuals we're talking about.

I've tried looking for hard numbers on HIV prevalence among swingers and the polyamorous and not found much. (A 2010 article in Sexually Transmitted Infections reports on a convenience sample of swingers, 4%-10% of whom had various STIs, though the paper didn't report on HIV specifically. Another article, in Sexologies, reports results from interviews with Montreal swingers, but HIV prevalence doesn't seem to have been assessed. These are the kinds of paper I'm finding.) Do you have hard numbers on how many swingers and polyamorous people in the West have HIV?

Three, my(!) theory explains why Southern Africa is distinct from similarly broad aggregates of humanity like heterosexuals in the rest of Africa, or heterosexuals in Europe (since those were the levels of aggregation under discussion earlier). You're now trying to apply the theory to a finer-grained population, specifically uncircumcized (if male) Western heterosexuals with MCPs, and when you zero in on an unrepresentative subpopulation like that, the relevant causes of differences in HIV rates will likely change, however applicable the theory is to the wider population. So your alleged falsification is not as clear-cut as you imply.

comment by Azathoth123 · 2014-08-31T20:59:54.995Z · score: -1 (3 votes) · LW · GW

Do you have hard numbers on how many swingers and polyamorous people in the West have HIV?

Do you have any hard numbers about how many partners typical Southern Africans have? As for polyamorous, there are a lot of them on LW. None have reported having to deal with AIDS in the community.

comment by satt · 2014-09-02T04:07:46.894Z · score: 6 (8 votes) · LW · GW

Do you have any hard numbers about how many partners typical Southern Africans have?

For the nth time, I'm not talking about the number of partners as such, but the number of concurrent partners. And yes, I do have hard numbers on those, some of which you'd have seen had you flicked through the SA J. HIV Med. article I've already linked and quoted. See figures 2 & 3 if you're having trouble finding them; figure 2's blurrier than I'd like but you can find numbers from the same data set plotted more clearly in this Lancet article, which is reference 23 in that SA J. HIV Med. article.

As for polyamorous, there are a lot of them on LW. None have reported having to deal with AIDS in the community.

Unless there's reason to think polyamorous LWers are broadly representative of polyamorous people in the West generally, this doesn't mean much. And I see no reason to think there is any reason, because you haven't given any, and LWers in general are hilariously unrepresentative of the West in general. As a concrete example (albeit one based on self-reported data), our mean IQ is allegedly 138. (And yes, the mean remains unrepresentatively high among polyamorous respondents. Looking at the data myself, the mean IQ is 144 for survey takers claiming to have multiple current partners.)

Also, even if we assume polyamorous LWers are representative of all polyamorous Westerners, there's another matter of numbers. While many people on our survey said they prefer polyamorous relationships (Yvain's summary says 234), there are far fewer LWers who report actually having multiple partners and being heterosexual and living in the West and actually posting on LW. Taking Yvain's public-use data for the 2013 survey, I count 86 people who said they had multiple partners, 43 of whom report being heterosexual, of whom 39 are left when I subtract out those in Brazil, Greece & Slovenia. How these people used LW seems to be a missing variable in the public data, but Yvain's summary says 49% of survey replies were from lurkers. If the same rate applies to our sub-sub-sub-sample, that'd leave only 20 relevant LWers, at which point it'd be much less surprising that the relevant group hadn't reported any AIDS concerns.

Stepping back and looking at this conversation as a whole, I'm going to walk away from it, because it just isn't productive. You're not showing any sign of changing your beliefs in the face of contrary evidence & argument, you're leaving me to take up almost all of the argumentative burden, and by all appearances you're either unable or unwilling to reason about this properly.

  • When I pointed out you made a fallacious inference, you didn't acknowledge that — not even to dispute it, oddly.

  • You repeatedly conflate two ideas which, although presumably correlated, are nonetheless distinct, and you're not respecting that distinction even though it matters greatly to the theory you wish to refute.

  • You show no sign of having even glanced at the sources I've referenced. Nor do you seem to be reading my replies carefully.

  • You don't refer to specific sources for your own claims. I still have no idea where you "herd" "~15 years ago" that subtype C was going to "break into the western heterosexual population real soon now".

  • When I explicitly ask whether you have specific HIV prevalence numbers, you dodge the question by demanding numbers you could've found by reading my sources yourself.

  • At least one of your questions, as stated, assumed a false premise. When I pointed that out, you didn't acknowledge it (again, not even to disagree).

  • You mostly argue by posing would-be killer objections to the orthodox model, one at a time and without substantiation, and when one objection gets knocked flat you don't acknowledge that but just move on to your next. I match that pattern of arguing to conspiracy theorists and others engaging in motivated cognition to defend a bizarre hypothesis; at no time is a semi-coherent alternative theory laid out by the arguer, just a procession of loosely linked anomalies presented as Devastating Critiques which turn out, on closer examination, to be irrelevancies, non-anomalies, or just really piss-weak evidence against the orthodox theory.

  • Speaking of bizarre hypotheses, the idea that a virus can be transmitted by anal sex but not at all by penis-in-vagina sex is quite an odd one, and you act as if utterly unaware of this. You argue like the idea's almost self-evidently true and everybody else is being inexplicably thick in disregarding it, even though it's an a priori unlikely hypothesis. (And even though you can't have applied much effort to understand why the relevant experts disregard it, because you raise objections they've tackled years ago in Googleable papers.)

The most parsimonious explanation of these facts is that, at least on this topic, you can't or won't think straight. Whichever is the case, you're wasting my time, so I'm done here.

comment by [deleted] · 2014-09-01T12:22:42.613Z · score: 4 (4 votes) · LW · GW

I'd guess that condom usage is way more widespread among LWers than among the general population of southern Africa.

comment by coffeespoons · 2014-08-20T16:10:16.155Z · score: 3 (3 votes) · LW · GW

I'm female, but I had no idea until after I'd had sex with bisexual men that the HIV risk was much higher than from sleeping with straight men. I used condoms anyway, but I was pretty shocked to learn about it. I still date bi men*, but I'm much stricter about making sure they've had STI tests than I used to be.

*My main social group are the UK bi/poly community, so two out of three of the men I've dated in the last few years have been bi.

comment by ShardPhoenix · 2014-08-19T08:44:17.181Z · score: 11 (11 votes) · LW · GW

HIV

Prevalence: Between 13 - 28%. My guess is about 13%.

Wow. That's at least an order of magnitude higher than I would have guessed. I even thought you might have accidentally omitted a decimal point at first.

comment by V_V · 2014-08-19T20:34:29.682Z · score: 9 (9 votes) · LW · GW

I had the same thought.

Indeed the prevalence in the general US population is 50x smaller: http://www.cdc.gov/hiv/statistics/basics/
I knew that MSM were a high risk group, but I didn't realize the risk was that high.

comment by sediment · 2014-08-19T21:16:28.472Z · score: 6 (6 votes) · LW · GW

As a heterosexual I'm not your target audience, but I voted this up for being a well-compiled and useful (to its audience) bit of research.

comment by ChristianKl · 2014-08-19T14:56:51.489Z · score: 5 (5 votes) · LW · GW

Whenever you speak of the prevalence I think it would you got to speak about the exact demographic it comes from. The US might have slightly different values than Europe.

comment by pianoforte611 · 2014-08-19T20:59:16.392Z · score: 6 (6 votes) · LW · GW

Not just slightly, the HIV prevalence in the UK among MSM is less than 5% using demographic data here and here. And the total HIV prevalence in the UK is relatively high for Europe see here.

I should probably mention this in the OP. I live in the US, and I couldn't exactly obtain a prevalence rate for every single country and every disease. But the US is an outlier with respect to many diseases.

comment by pianoforte611 · 2014-08-19T00:42:44.312Z · score: 4 (4 votes) · LW · GW

Quick thanks to Omid who came up with the idea for this post and gave me several suggestions about the content of the post.

comment by RyanCarey · 2014-08-24T07:01:05.229Z · score: 2 (4 votes) · LW · GW

This is great data. Now, it would be great to add some interpretation, either in a conclusion paragraph, or in a comment.

My interpretation is: "The prevalence of STDs in MSM is high, including 13% for HIV, especially considering their substantial impact on quality of life. If you're having anal intercourse, even if you're using a condom consistently, the associated risk is orders of magnitude higher than the risk from unprotected oral sex. Choice of sex act and testing your partner seem like relatively reliable ways to reduce risk"

comment by [deleted] · 2015-08-27T07:20:45.492Z · score: 1 (1 votes) · LW · GW

I want to have sex with this girl I just started dating without a condom, and pleasure her orally. I haven't done either of those things before, but I have a plan... However Mansons guide doesn't seem very helpful for me cause I think she'd be a virgin or pretty inexperienced.

The risk of aquiring HIV from sexual intercourse is actually super low. It's effectively a non-issue, particularly if you are having hetereosexual sex that's not regularly with a seropositive partner. Effectively, you're safe, even if you bang hookers like me :) It's good to get checked up, and you don't even need to give your real name: When I attended my cities sexual health clinic I used the anglicisation of my first name and only the first name of my last name, as my full name. They are happy for people to do this.

a key factor in the spread of the disease is the viral load. During the chronic infection stage, the load is low enough that it requires several contacts between two individuals over a short period of time for the infection to spread.

But what of the acute stage of the disease when the viral load is greater and the chances of infection much higher? Again Rocha and co say the disease cannot spread through the network, even if the infection rate is 100 per cent.

The reason is the time between sexual contacts. Rocha and co say there is an epidemic threshold in which the disease spreads if it is infectious for more than about a month. However, the acute stage of HIV appears to last for only for a couple of weeks. This just isn’t long enough to spread given the rate of contact that occurs in this network.

Fairly sure it's confounding by drug use with poverty, being a man who does anal, or high risk personality that explains sex workers having high rates of HIV, rather than their occupation.

comment by coffeespoons · 2014-08-20T11:58:39.343Z · score: 1 (1 votes) · LW · GW

Regarding HIV, what about Truveda?

comment by pianoforte611 · 2014-08-21T00:02:08.203Z · score: 1 (1 votes) · LW · GW

Its the same as pre exposure prophylaxis.

comment by coffeespoons · 2014-08-21T14:55:20.823Z · score: 1 (1 votes) · LW · GW

Ah, sorry, I must have missed that due to reading too quickly.