Back when my condom broke with this chick, I began to research STDs and their transmission rates. Bacterial, curable STDs (such as chlamydia and gonorrhea) have a very high rate of transmission. STDs like HIV have a very LOW rate of transmission. The rate for male to female transmission is 8 people in every 10,000 exposures. This is only for vaginal sex, oral sex transmission rate is so low that it is reported to be negligible. The HIV virus is very fragile and needs a specific environment to transfer hosts (according to the research paper)
Gay men have the worst odds, something around 130 per 10,000 exposures.
The reason for these transmission rates is that the virus has a hard time permeating the mucous membrane (urethra, vaginal cavity), but it has an easier time permeating the membrane of the areas gay men use (pause

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With transmission rates like these, chances are that if you hit raw on a regular basis, its likely that you could have had sex with an HIV positive partner multiple times and missed the bullet.
I do completely agree that no one is worth the risk though.
Stay educated folks