A person with an untreated Sexually Transmitted Infection (STI), is at higher risk for HIV.
When a person is infected with an STI (for example, chlamydia, gonorrhea, syphilis or herpes), the immune system tries to fight off the STI by sending white blood cells to the site of the infection (typically the rectum, penis, throat or vagina). HIV targets these white blood cells. Because the site is inflamed (sometimes including open sores), and there are lots of white blood cells present, HIV can be picked up from a partner more easily.
If a person who already has HIV gets another STI, this will cause inflammation at the site of infection, and draw HIV-infected white blood cells to the site. This makes it easier for them to pass on HIV to their sexual partner(s).
For more information call the AIDS and Sexual Health InfoLine at 1-800-668-2437 (English and multilingual line) or 1-800-267-7432 (French line) or check out the Resources section of this site.