Katzenstein was one of the first American doctors to focus his efforts on saving HIV-positive Africans.
Taking six shots a year, as opposed to 365 pills, yielded huge advantages among women in a recent trial.
Nations that don't penalize same-sex activity have lower rates of HIV among men who have sex with men.
The finding is further proof HIV crossed over to humans decades before it turned into a pandemic.
The two international organizations say service disruptions could cause massive suffering.
Attacked by a mob, gay, HIV activist Edafe Okporo fled Nigeria. Listen as he talks about being gay in a country where it is illegal and HIV stigma is huge.
This early ancestor is to blame for passing the bothersome virus onto modern humans.