Immunology
HΓV cripples the body’s immunologic system, making an infected individual vulnerable to other disease-causing agents in the environment. The most common of these opportunistic infections in AIDS patients has been pneumocystis pneumonia, an infection previously seen principally among patients receiving immunosuppressive drugs.
In addition to pneumocystis, AIDS patients are prone to other infectious agents such as cytomegalovirus (CMV), Candida albicans (a yeastlike fungus), and Toxoplasma gondii (a protozoan parasite). There is also evidence that infection with HIV makes individuals more vulnerable to infection with tuberculosis. A resurgence of tuberculosis has been reported in nations with a high incidence of AIDS.Immunologic damage occurs by depletion of a specific type of immune cell, a white blood cell known as a helper T4 lymphocyte. Destruction of these cells accounts for the vulnerability to many normally harmless infectious agents. In some cases, infection of the central nervous system with HΓV may cause damage to the brain and spinal column, resulting in severe cognitive and motor dysfunction. In its late manifestations, AIDS causes severe wasting. Death may occur from infection, functional failure of the central nervous system, or starvation.