I found a statement at CDC that may be of interest in a 1998 paper with the really hot title Management of Possible Sexual, Injecting-Drug-Use, or Other Nonoccupational Exposure to HIV.

Quote:


Probability of Transmission From One HIV Exposure

HIV can be transmitted efficiently through blood transfusions: an estimated 95% of recipients become infected from transfusion of a single unit of infected whole blood. The per-contact probability of transmission from an HIV-infected source is much lower for injecting-drug-use and sexual exposures. The risk for HIV transmission per episode of intravenous needle or syringe exposure is estimated at 0.67% (5). The risk per episode of percutaneous exposure (e.g., a needlestick) to HIV-infected blood is estimated at 0.4% (upper limit of 95% confidence interval {CI} = 0.8%) (6). The risk for HIV transmission per episode of receptive penile-anal sexual exposure is estimated at 0.1%-3%; the risk per episode of receptive vaginal exposure is estimated at 0.1%-0.2% (7). No published estimates of the risk for transmission from receptive oral exposure exist, but instances of transmission have been reported (8,9).


The author probably isn't thinking of DAP here. Also, these estimates probably assume that the HIV+ partner has stabilized HIV levels and not the highly elevated levels a week or two after infection that Darren probably had. Finally, some meat puppets really are big and may skew things. The odds in the current outbreak are probably higher than what’s show here, but it’s not unreasonable for first-generation contacts to be hopeful.
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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