Here's the bottom line:
junkies have for years contracted AIDS because they destroy their immune systems.
The initial cases of AIDS among the gay community were those who killed their immune systems via long work hours, poor diet, specific "recreational" drug use, little sleep and unprotected sex with random partners.
Intially, Karposi Sarcoma was a key indicator of AIDS...this was exactly what happened to junkies. As the years went by, more and more diseases that were among the general population for decades (and non-fatal for the most part) were added (and then later subtracted) as "AIDS indicators".
When HIV was announced as the pre-cursor to AIDS, being typed for HIV anti-bodies was considered an eventual/inevitable AIDS development. However over the years, you've had people who were NOT HIV positive develop aids...people who were HIV positive, stopped or took no medication and NEVER developed AIDS.
The HIV test for Africans is different from that of Europe and North America. Odd, since every other type of virus can be identified with one type of test world wide.