I'm not even going to try to sound like an authority regarding this, because I most definitely am not- but I think this thread has drifted from the topic.
"Bug Chasing" is NOT about someone who is HIV+ going around and infecting others. Its about someone who is HIV NEGATIVE who seeks out positive partners. From what I gathered from a discussion we had about it in college (as well as the article) is that the negative person is "chasing the bug" just so that they no longer have to worry about becoming infected; they see it almost as an inevitable event, that someday they will most certainly become HIV+, so they want to get it done and out of the way so that they can continue to have sex without wondering "will I get it this time?" Its like some sort of safety blanket- knowing that they are already infected means that they can have all the unprotected sex they want and not have to worry any longer. Once they have "caught the bug", most seek out other positive partners (and not get off on infecting others) and have unprotected sex from that point forward.
Someone please correct me if I'm wrong. Thanks!