When found early, many STDs are treatable or conveniently treatable. HIV (human immunodeficiency virus) is an infection that assaults the body's immune system, ruining the CD4 cells (also called T cells). It is primarily spread out by having rectal or genital sex or sharing shot medicine equipment with a person that has HIV. Over time, HIV weakens the body's capability to fight off infections and also illness. Herpes is a typical viral infection that is brought on by the herpes simplex virus (HSV).