[King Prout]

well, yes. decent epidemiological explanation, but...
oversimplified.
1. AIDS spreads fastest and hardest among certain demographics, and seems rather handicapped among others. The "easy-prey" demographics can be expected to be wiped out, or reduced in number from their present glut population. Once that happens, the population and range of the deadly pathogen will also decline.
2. long term, infectious diseases tend to mutate into less-efficient pathogens. Too efficient, and they kill their hosts off faster than their hosts can replace. AIDS/HIV is none-too-efficient, but it is still lethal in 10+/-5 years... ie: less than the average generation.
3. If (unlikely) it ever got bad enough - and you know this - draconian measures such as mandatory testing, publication of positive lists, and hard medical isolation would be imposed. We can do things today that were not dreampt of back in the plague years.

[NetValue]

Well then try this:

http://www.usaid.gov/press/releases/2002/pr020708.html