The following three conditions must be met for HIV to be transmitted (SFAF, n.d.):
Infection can happen only if at least one of the people involved (eg, a sexual partner, blood or organ donor, or user of injection drugs) is infected with HIV. Certain behaviors alone, such as anal sex, do not cause HIV infection.
The amount or concentration of HIV in the infected body fluid partly determines whether infection happens. The greater the concentration of HIV in the body fluid, the greater the chance that a person exposed to the body fluid will become HIV-infected. HIV is found in very low concentration—or is absent—in saliva, sweat, tears, and urine. It is found in medium concentration in anal secretions, and in high concentration in blood, semen, vaginal secretions, and breast milk. Thus, only a small amount of infected blood, semen, vaginal fluids, or breast milk is enough to infect someone, whereas much larger amounts of anal secretions are needed for HIV transmission. To date, there are no known cases of HIV transmission through saliva, tears, sweat, or urine.
Different people also have different concentrations of HIV, depending, in part, on their stage of HIV disease. In the first, primary stage of infection, people have much higher concentrations of HIV in their blood than they do in the middle, asymptomatic stage of infection. Concentrations of HIV rise during the late stage and full-blown AIDS (Hare, 2004; Lawn, Butera, & Folks, 2001). It is therefore more likely that a person with HIV will transmit HIV to an uninfected sexual or injecting partner during the primary stages of infection and when the infection has progressed to advanced HIV disease (AIDS) than during the middle, asymptomatic stage, which can last several years.
It is not enough just to touch HIV-infected fluid to become infected. Healthy, unbroken skin is an excellent barrier that prevents HIV from getting into the body. HIV can only enter through an open cut or sore, or through contact with the mucous membranes of the anus, rectum, genitals, mouth, or eyes.
Discussion question: Describe the three conditions that must be present for HIV to be transmitted.
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