Sexually transmitted infections (STIs) that cause open sores on the
genitals, like herpes, syphilis, or chancroid, can increase HIV
transmission. This is because the open sores make it easier for the HIV
virus to get into the body. Also, when you have an infection your immune
system kicks up a notch, producing disease-fighting cells called
macrophages. The HIV virus can bind to these macrophages in mucus
membranes like the vagina or anus and thus cross these membranes into
the blood stream. If you have an infection in your genital area,
macrophages are especially concentrated there, giving HIV more
opportunities to enter your body.
