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
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.
At an (unrealistically?) independent 0.5% chance per act, a 50% chance of transmission would require 139 sex acts — hardly “years and years”.
(ETA: yes, unrealistically, according to this abstractfound by Perplexed: “However, in comparison with nonparametric estimates, the model assuming constant infectivity appears to seriously underestimate the risk after very few contacts and to seriously overestimate the risk associated with a large number of contacts. Our results suggest that the association between the number of unprotected sexual contacts and the probability of infection is weak and highly inconsistent with constant per-contact infectivity.”)
So in my mind this makes it technically impossible for HIV to be an STD.
At best, this can show that pandemic AIDS can’t primarily result from sexual transmission of HIV, which is evidence that AIDS has causes other than HIV, but also that pandemic AIDS spreads through other means (as suggested here, e.g.).
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.
If you’re thinking of rates in the modern developed world, STDs are unsurprisingly more common when and where treatment is less available:
...in New York City, serologic testing in 1901 indicated that 5%-19% of all men had syphilitic infections. (source)
Studies of pregnant women in Africa have found rates for gonorrhea ranging from 0.02% in Gabon to 3.1% in Central African Republic and 7.8% in South Africa.… [syphilis] rates of 17.4% in Cameroon, 8.4% in South Africa, 6.7% in Central African Republic and 2.5% in Burkina Faso.… (source)
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
At an (unrealistically?) independent 0.5% chance per act, a 50% chance of transmission would require 139 sex acts — hardly “years and years”.
That is for the highest transmission activity—receptive A, so be careful not to cherry pick. Yes − 139 unprotected sex acts. It would take 1390 unprotected insertive A sex acts to reach a 50% chance of transmission.
So with some assumptions, mainly—gay bathouses and no condom use—yes the virus could spread horizontally, in theory. Although that population would necessarily first acquire every other STD known to man, more or less.
But in the general heterosexual population, not a chance. If you compare to the odds of pregnancy from unprotected sex, the insane requisite amounts of unprotected sex with strangers would result in a massive baby epidemic and far more vertical transmissions long before it could ever spread horizontally in the hetero population.
I don’t know why you mention “modern developed-world rates” and then have a link to 1901 NY and Africa . . .
So in my mind this makes it technically impossible for HIV to be an STD.
At best, this can show that pandemic AIDS can’t primarily result from sexual transmission of HIV, which is evidence that AIDS has causes other than HIV, but also that pandemic AIDS spreads through other means (as suggested here.
You don’t need the “at best” qualifier, but yes I agree that is what this shows. Showing that however opens a crack in the entire facade. Perhaps not a critical failure, but a significant doubt nonetheless.
If the orthodox position had updated on the evidence, and instead changed their claim to “HIV is a borderline infectious disease that spreads primarily through the prenatal and blood-borne routes”, then I would give them more creedence. Of course, for political reasons alone they could never admit that.
Funny to think of pregnancy as curable, but yes of course that’s true. However, it doesn’t really change the numbers much.
Also, from what I have read about the early 80′s bathouse scene, it is possible that many of those guys did acquire every STD known to man, so at least in that case the sexual transmission route could work even with such terribly low efficiency.
Regardless, it seems strange to label it as a STD from an evolutionary perspective, it doesn’t fit that profile, and it seems incredibly unlikely it could have evolved as such.
Essentially the government committed to a public awareness campaign that HIV was ‘rapidly growing’ in the heterosexual community, and this became part of the dogma. It is politically motivated—it’s anti-sex message appeases religious conservatives while also shifting attention away from the gay bathouse scene, so it sort of benefits everyone politically, regardless of whether it’s actually true.
At an (unrealistically?) independent 0.5% chance per act, a 50% chance of transmission would require 139 sex acts — hardly “years and years”.
I don’t see why epidemiology should care about the 50% threshold. The relevant number is the expected number of transmissions per year. Thus independence is irrelevant.[1] At 200 anal tops per year per infected person, incidence should double yearly. And every top requires a bottom, so that’s 400 anal sex acts per year for just doubling. It seemed to spread more quickly than that, but maybe 800 and 4x per year works. It seems just barely plausible with this transmission rate. I’m not sure of the details of bathhouses, but I thought that there was a lot of non-anal sex, too.
[1] independence is relevant if 70s gays were systematically different from the people in the study; and they probably were, eg, they probably had higher rates of STDs
And every top requires a bottom, so that’s 400 anal sex acts per year for just doubling. It seemed to spread more quickly than that, but maybe 800 and 4x per year works.
It took 8 years (until August 1989) for the first 100,000 cases to be reported; the second 100,000 were reported in just 2 years (by November 1991). The half million total was passed in October of 1995.
This seems to indicate a doubling time of about 2 years.
ETA: Also according to that page, the patient with the first confirmed HIV infection died of AIDS in 1968, so the growth rate of AIDS before 1989 was at most 1.73x per year.
OK, maybe doubling works. But it’s important to distinguish different populations. You should expect it to spread faster through the bathhouse scene than through the rest of the gay community than through the straight community. So it should slow down once it exhausted the bathhouse regulars (something like weekly visits) or when AIDS shut down that scene. If that happened around 1985 and there’s a 10 year incubation period, then the 1995 numbers still include bathhouse effects. Diagnoses were increasing at 3x or 4x in the early 80s: 100 in fall ’81 to 250 in mid ‘82 to 1000 in early ‘83 to 3000 by the end of the year. From ‘83 to ’89 it was merely doubling and it slowed after that. Of course, there are problems with diagnosis numbers early in an epidemic, but death followed quickly, in weird ways, so these numbers are probably good enough. Yes, there were people with AIDS in 60s, but that 1.73x includes time to get to the bathhouse scene.
One problem with this simplified model is assuming every sexual act is with a new partner, which would only be true in the very early stages.
I think your analysis is on the right track though, and it seems barely plausible with this transmission rate, assuming negligible condom use and an intense bathhouse scene. However, in standard theory HIV progresses to AIDS in about 10 years, so this sets a timer which starts removing vectors from the population.
Thus the exact exponent matters considerably. If incidence can only double every year, then after 10 years you get 2^10 ~ 1000 cases.
If incidence doubles every 6 months (quadruples every year), then you get a million cases after ten years.
If you consider that all other STD’s would infect this population before HIV, then one has to wonder how that would effect condom use, and how that changes the model.
So do you find the transmission rate and make the model before you decide that HIV was an STD which spread this way, or after?
One problem with this simplified model is assuming every sexual act is with a new partner, which would only be true in the very early stages.
It assumes that every sexual act is with an uninfected partner. Perhaps that’s what you meant, but then I wouldn’t have used “very.”
If you consider that all other STD’s would infect this population before HIV, then one has to wonder how that would effect condom use, and how that changes the model.
I think this is pretty well documented. STDs were routine and not a big deal (treatable!) in the 70s gay scene. Thus they did not cause condom use.
At an (unrealistically?) independent 0.5% chance per act, a 50% chance of transmission would require 139 sex acts — hardly “years and years”.
(ETA: yes, unrealistically, according to this abstract found by Perplexed: “However, in comparison with nonparametric estimates, the model assuming constant infectivity appears to seriously underestimate the risk after very few contacts and to seriously overestimate the risk associated with a large number of contacts. Our results suggest that the association between the number of unprotected sexual contacts and the probability of infection is weak and highly inconsistent with constant per-contact infectivity.”)
At best, this can show that pandemic AIDS can’t primarily result from sexual transmission of HIV, which is evidence that AIDS has causes other than HIV, but also that pandemic AIDS spreads through other means (as suggested here, e.g.).
If you’re thinking of rates in the modern developed world, STDs are unsurprisingly more common when and where treatment is less available:
That is for the highest transmission activity—receptive A, so be careful not to cherry pick. Yes − 139 unprotected sex acts. It would take 1390 unprotected insertive A sex acts to reach a 50% chance of transmission.
So with some assumptions, mainly—gay bathouses and no condom use—yes the virus could spread horizontally, in theory. Although that population would necessarily first acquire every other STD known to man, more or less.
But in the general heterosexual population, not a chance. If you compare to the odds of pregnancy from unprotected sex, the insane requisite amounts of unprotected sex with strangers would result in a massive baby epidemic and far more vertical transmissions long before it could ever spread horizontally in the hetero population.
I don’t know why you mention “modern developed-world rates” and then have a link to 1901 NY and Africa . . .
You don’t need the “at best” qualifier, but yes I agree that is what this shows. Showing that however opens a crack in the entire facade. Perhaps not a critical failure, but a significant doubt nonetheless.
If the orthodox position had updated on the evidence, and instead changed their claim to “HIV is a borderline infectious disease that spreads primarily through the prenatal and blood-borne routes”, then I would give them more creedence. Of course, for political reasons alone they could never admit that.
Many non-AIDS STIs, and pregnancy, are curable.
Funny to think of pregnancy as curable, but yes of course that’s true. However, it doesn’t really change the numbers much.
Also, from what I have read about the early 80′s bathouse scene, it is possible that many of those guys did acquire every STD known to man, so at least in that case the sexual transmission route could work even with such terribly low efficiency.
Regardless, it seems strange to label it as a STD from an evolutionary perspective, it doesn’t fit that profile, and it seems incredibly unlikely it could have evolved as such.
It’s also funny to call babies an epidemic.
Life is a disease. It is transmitted by sex and ends deadly always.
touche!
What are the political reasons? Staying on-message and retaining funding, or something more specific?
Essentially the government committed to a public awareness campaign that HIV was ‘rapidly growing’ in the heterosexual community, and this became part of the dogma. It is politically motivated—it’s anti-sex message appeases religious conservatives while also shifting attention away from the gay bathouse scene, so it sort of benefits everyone politically, regardless of whether it’s actually true.
I meant “rates are higher outside the modern developed world”. Rephrased for clarity.
I don’t see why epidemiology should care about the 50% threshold. The relevant number is the expected number of transmissions per year. Thus independence is irrelevant.[1] At 200 anal tops per year per infected person, incidence should double yearly. And every top requires a bottom, so that’s 400 anal sex acts per year for just doubling. It seemed to spread more quickly than that, but maybe 800 and 4x per year works. It seems just barely plausible with this transmission rate. I’m not sure of the details of bathhouses, but I thought that there was a lot of non-anal sex, too.
[1] independence is relevant if 70s gays were systematically different from the people in the study; and they probably were, eg, they probably had higher rates of STDs
Why “more quickly than that”? From Epidemiology of HIV/AIDS in the United States:
This seems to indicate a doubling time of about 2 years.
ETA: Also according to that page, the patient with the first confirmed HIV infection died of AIDS in 1968, so the growth rate of AIDS before 1989 was at most 1.73x per year.
OK, maybe doubling works.
But it’s important to distinguish different populations. You should expect it to spread faster through the bathhouse scene than through the rest of the gay community than through the straight community. So it should slow down once it exhausted the bathhouse regulars (something like weekly visits) or when AIDS shut down that scene. If that happened around 1985 and there’s a 10 year incubation period, then the 1995 numbers still include bathhouse effects. Diagnoses were increasing at 3x or 4x in the early 80s: 100 in fall ’81 to 250 in mid ‘82 to 1000 in early ‘83 to 3000 by the end of the year. From ‘83 to ’89 it was merely doubling and it slowed after that. Of course, there are problems with diagnosis numbers early in an epidemic, but death followed quickly, in weird ways, so these numbers are probably good enough. Yes, there were people with AIDS in 60s, but that 1.73x includes time to get to the bathhouse scene.
One problem with this simplified model is assuming every sexual act is with a new partner, which would only be true in the very early stages.
I think your analysis is on the right track though, and it seems barely plausible with this transmission rate, assuming negligible condom use and an intense bathhouse scene. However, in standard theory HIV progresses to AIDS in about 10 years, so this sets a timer which starts removing vectors from the population.
Thus the exact exponent matters considerably. If incidence can only double every year, then after 10 years you get 2^10 ~ 1000 cases.
If incidence doubles every 6 months (quadruples every year), then you get a million cases after ten years.
If you consider that all other STD’s would infect this population before HIV, then one has to wonder how that would effect condom use, and how that changes the model.
So do you find the transmission rate and make the model before you decide that HIV was an STD which spread this way, or after?
It assumes that every sexual act is with an uninfected partner. Perhaps that’s what you meant, but then I wouldn’t have used “very.”
I think this is pretty well documented. STDs were routine and not a big deal (treatable!) in the 70s gay scene. Thus they did not cause condom use.