A syndrome resulting from the acquired deficiency of cellular immunity caused by the human immunodeficiency virus (HIV). It is characterized by the reduction of the Helper T-lymphocytes in the peripheral blood and the lymph nodes. Symptoms include generalized lymphadenopathy, fever, weight loss, and chronic diarrhea. Patients with AIDS are especially susceptible to opportunistic infections (usually pneumocystis carinii pneumonia, cytomegalovirus (CMV) infections, tuberculosis, candida infections, and cryptococcosis), and the development of malignant neoplasms (usually non-Hodgkin lymphoma and Kaposi sarcoma). The human immunodeficiency virus is transmitted through sexual contact, sharing of contaminated needles, or transfusion of contaminated blood.