bloodstream
HIV spreads through contact between an infected persons body fluids and another person's bloodstream or mucus membranes, which are found in the mouth, nose, and genital areas. Body fluids that may contain HIV are blood, semen, vaginal fluid, and breast milk. The virus can spread through sexual contact or shared drug needles. It can also spread from an infected mother to her baby during childbirth or breastfeeding. Saliva can carry the HIV virus, but it won't spread it, unless the saliva gets into the bloodstream. Other body fluids such as urine and sweat do not contain the virus. HIV does not spread in any fluid in which the host cells cannot survive.