Unprotected gay sex is one of the easiest ways to pass on HIV (needles is most likely number 1 if you want to rank them). However, semen is the most efficient way to cause an infection (semen is high in iron which is essential for making the virion extremely infectious). BUT, the vast majority of HIV infections in the world (roughly 95%) are passed on during unprotected heterosexual sex. In the US, the hetero number drops to 60% or so.
There is a stigma with men, especially in Africa, attached to wearing condoms. Dumbasses. There is also astigma with prostitutes in Africa about not telling anyone you are HIV + and making men wear condoms. I don't know about the Indian subcontinent and SE asia, but I imagine it is quite the same there too.
HIV knows no racial, political, or geographic boundaries. It is an STD, and like it's name says, it will NEVER be eliminated. It may be controlled someday through vaccines, etc, but there will be many millions of people throughout the world who die of it.
What really pisses me off aren't the idiot homos, drugs, hetero having unprotected sex, needles, etc--you are paying for your careless lifestyle with your life. I feel bad for the kids who get infected and grow up with AIDS--the ones who have no choice.
Like I said, HIV is an STD, and until people can control the urges, brush aside the stigma of condoms, and become educated about transmission, it will propagate very well across the planet like syphillis, gonorhea, etc.