A few years ago, someone gave a presentation to a semi-official body on transgendered people and sex work. Most were doing sex work to pay for gender reassignment surgery.
However she said that around 70-80% of MTF sex workers were HIV+ and gave several reasons for this, including being more vulnerable to taking more money to have (anal) sex without a condom.
She also opined that there was a very high rate of HIV infection in MTF people generally (much higher than the about one in sex or seven for gay men in London).
Now, it may just be the people I know, but this sounds extremely high to me. Had I been at the meeting, I'd have been asking 'Where's the evidence for that?'
Not least because as I understand it most of the surgeons who do gender reassignment won't take HIV+ patients.