Answer: b, c, d Acquired immunodeficiency syndrome (AIDS) is a syndrome caused by the human retrovirus (HIV-1) that infects T lymphocytes and causes severe immunosuppression. Individuals who become infected with HIV are prone to a variety of infections and different types of malignancy. A spectrum exists in which patients regress from asymptomatic infection, to development of AIDS-related complex (ARC) of diseases to AIDS itself. Common infections occurring in patients with AIDS are Pneumocystis carinii pneumonia; CMV pneumonitis; gastritis, hepatitis and meningitis due to Cryptococcus neoformans; and pneumonia and disseminated infection due to atypical mycobacteria. Predisposition to these infections is due, in part, to the lymphotrophic nature of HIV, which markedly reduces the number of helper T cells as well as the absolute number of T cells. HIV detection typically consists of initial ELISA screening, but this test has about a 1–3% false-positive rate, thus mandating all positive tests be confirmed by the western immunoblot analysis. Treatment of ARC and AIDS consists of aggressive antiinfective therapy once a specific infection occurs and the use of AZT. AZT has been shown to prolong survival when administered early in the course of disease and is considered routine therapy