People with AIDS eventually die of infections or other ailments because their failing immune system cannot mount a resistance against disease. At present, there is no cure for AIDS, but drugs are available that greatly reduce the amount of virus in the body and delay the progression of infection. Many of the infections and other diseases that result from HIV infection can also be treated effectively. An infected woman can pass the virus to her baby during pregnancy or breast-feeding. HIV infection can also result from the transfusion of blood contaminated with the virus, although now all blood donors are tested, and blood from infected donors is disposed of or used for laboratory research only.
Infection requires fairly large amounts of the virus and direct exchange of body fluids.
People who have their blood or other fluids drawn for medical purposes using disposable needles are at no risk of infection. After entering the body, HIV inserts its genes into the genetic material of cells and uses the cell's machinery to make new copies of the virus. HIV may live in the body for many years without causing obvious damage, but gradually it destroys the infected cells. Its primary targets are immune cells known as helper T cells, or CD4 cells, which are an important part of the body's immune system. Definition of AIDS As the number of CD4 cells in the blood drops, the immune system deteriorates.