The cumulative epidemiologic data indicates that transmission of AIDS requires direct intimate contact with or intravenous innoculation of blood and blood products, semen or tissues. Although the theoretical possiblity of rare or low risk alternative modes of transmission cannot be totally excluded, these are not documented in the medical literature. The major mode of transmission is sexual. Also important is intravnous transmission by shared needles. AIDS is not transmitted by casual contact, fecal-oral or airborne routes or by contaminated food or drinking water.
People are at risk of AIDs to the extent that they are exposed to blood and certain bodily fluids.
Contact with saliva, tears and sweat has not been shown to result in infection. In general the source of the virus in the body fluids other than blood is lymphocytes. All body fluids that contain lymphocytes can harbor the virus. Sweat does not contain lymphocytes. Fresh blood must encounter an open would in order for infection to be spread during routine exercise.