Most HIV-1 infections worldwide are acquired sexually after exposure to semen. Research shows that co-infection with ulcer-causing sexually transmitted diseases, such as syphilis and herpes, increases the chance of HIV-1 transmission between sexual partners. Studies have also associated urethritis (inflammation of the urethra) with high levels of HIV in semen. Gonorrhea or chlamydia frequently cause urethritis in men, but recent studies suggest another sexually transmitted infection, Mycoplasma genitalium, is a cause of urethritis. Dr. Thomas Lampinen is investigating the association of Mycoplasma genitalium with urethritis and accumulation of HIV-1 in semen of young gay and bisexual men in BC. The study could identify Mycoplasma genitalium as a potentially treatable co-infection linked to the spread of HIV-1. The research has special urgency given recent recommendations to delay antiretroviral therapy, which will likely cause an increase in infectiousness among men with HIV-1.