In addition to the risky partners mentioned above, other risk groups would include recipients of transplants or transfusions. Like hemophiliacs these people are at risk of being infected by untested or poorly tested blood products used for their transfusions. This retrovirus reproduces at a very high rate and ultimately overcomes the ability of the immune system to respond. AIDS results when the immune system is significantly weakened and opportunistic infections begin. Direct exchange of bodily fluids is needed for the AIDS virus to be passed on from one person to another.
Direct exchange takes place through sexual relations or through the sharing of needles.
Blood transfusion or injury may also expose one to the blood of an infected person. Infected mothers may transmit the virus to their unborn child or at birth and through breast feeding. HIV is not an airborne virus and cannot be transmitted by casual contacts. By the year 2000, the number of people infected is expected to reach 40 million. In the United States, AIDS is presently the number one killer for individuals between the ages of 25 and 44.