A syndrome of the immune system characterized by opportunistic diseases, including candidiasis (both oropharyngeal and vulvovaginal), pneumocystis carinii pneumonia, oral hairy leukoplakia, herpes zoster, idiopathic thrombocytopenic purpura, cervical dysplasia and cervical carcinoma, Kaposi’s sarcoma, pelvic inflammatory disease, toxoplasmosis, isosporiasis, cryptococcosis, non-Hodgkins lymphoma, and peripheral neuropathy. Tuberculosis may also be considered to be an opportunistic infection. The syndrome is caused by the human immunodeficiency virus (HIV-1, HIV-2), which is transmitted by exchange of body fluids (notably blood and semen) through sexual contact, sharing of contaminated needles (by IV drug abusers), accidental needle sticks, contact with contaminated blood, or transfusion of contaminated blood/blood products. Hallmark of the immunodeficiency is depletion of T4+ helper/inducer lymphocytes, primarily the result of selective tropism of the virus for the lymphocytes. Persistent generalized lymphadenopathy, fever, weight loss, and diarrhea of long duration (lasting more than 1 month) are associated with early stages of the disease. Syn: acquired immunodeficiency syndrome.
As of 1994, the Centers for Disease Control put the number of HIV-infected people in the U.S. at 1 million, and those with full-blown AIDS at 339,250. Some 10 million people are estimated to be infected worldwide, with the highest suspected incidence in some Central and East African countries, where as much as a third of the adult population may be HIV-positive. Although in the U.S. the rise in new AIDS cases appears to have peaked among men, perhaps in part because of public education efforts, the number of new cases continues to rise rapidly among women and children (especially teens). Whereas female AIDS patients represented only 7% of total cases before 1985, they now account for an estimated 13%. Those groups showing the greatest rate of increase were Latino and black women who used IV drugs or had a partner who did. AIDS is the leading cause of death among men 25 to 44, and the fourth leading cause among women in the same age group. The speed with which researchers have identified and characterized the presumed causative agent of AIDS, the HIV virus, may be unparalleled in the history of medicine. However, therapies for halting or reversing the virally mediated collapse of immune function have yet to be devised, and work on vaccines has been stymied by the ability of HIV to mutate rapidly. See HIV.