Royston, after a quarter of a century, there has surely been ample time for HIV to cross over to the straight community.
What is your evidence?
This from BMJ, 2005. "Although the number of people becoming infected with HIV through heterosexual intercourse in the United Kingdom is rising steadily, most of the overall rise in HIV diagnoses among heterosexuals is among people who originate from and were infected abroad, mainly in Africa.1 "
http://www.bmj.com/cgi/content/full/330/7503/1303