The wording in the article is a bit off IMHO. A virus by itself is not an epidemic, and certainly not if the virus is undetected for decades by virtue of being relatively scarce. An epidemic is when a harmful virus starts to spread at an unexpected, high rate, causing a lot of unexpected damage in the process. Obviously we'll never know precisely how HIV/AIDS started in humans and when, but the epidemic itself began in bathhouses in New York City, San Francisco and Los Angeles. All of this is very well-documented in this book:
http://www.amazon.com/Band-Played-Politics-Epidemic-20th-Anniversary/dp/0312374631/ref=sr_1_1?ie=UTF8&qid=1330448101&sr=8-1If you don't want HIV/AIDS, use condoms and don't share needles, and you'll probably be fine. In particular, it's highly advisable not to engage in receptive anal sex (at least outside of a committed relationship). That's one tidbit they don't always share in sex ed classes these days, for whatever reason(s).
It's mind-boggling that the rate of HIV infection is on the rise again.
