"How do you know what you know?".
D002170:Canada / Q000453:epidemiology; D015658:HIV Infections / Q000453:epidemiology / Q000517:prevention & control* / Q000635:transmission; D006266:Health Education / Q000379:methods*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D040241:Social Marketing; D047568:Unsafe Sex