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.
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.