Thanks Gen, that's very complete.

You might add a "Further Reading" footnote to your paper pointing to the CDC HIV/AIDS area at http://www.cdc.gov/hiv/dhap.htm since there's a lot of garbage on the web about this.
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"If they can't picture me with a knife, forcing them to strip in an alley, I don't want any part of it. It's humiliating." - windsock