Update: acquired immunodeficiency syndrome--United States.

Between June 1, 1981, and January 13, 1986, the Centers for Disease Control (CDC) were notified of 16,458 (16,227 adults and 321 children) cases of acquired immunodeficiency syndrome (AIDS) in the US. Of these, 8361 (51% of adults and 59% of the children) have died, including 71% of those diagnosed before July 1984. 90% of adults AIDS cases were 20-49 years old, and 93% were men. Significant changes have occurred over time in the distribution of specific diseases reported. Pneumocystis carinii peneumonia accounts for 43% of opportunistic infections among AIDS victims and its incidence relative to other infections, especially Kaposi's sarcoma, continues to increase. 94% of AIDS patients can be placed in groups that suggest a possible means of disease acquisition. Follow-up investigation has indicated that many of the AIDS patients who could not originally be placed in a high-risk category were from countries where heterosexual transmission may account for many AIDS cases, had histories of gonorrhea or syphilis, or had sexual contact with a female prostitute. 75% of pediatric AIDS patients have come from families where 1 or both parents had AIDS, 14% had received blood or blood products before the onset of illness, and 15% had hemophilia. The number of AIDS cases not classifiable into previously identified risk groups is not increasing proportionately faster than the number of cases in identified risk groups. Moreover, although the number of AIDS cases reported each 6-month period continues to increase, the increase has not been exponential. Currently reported AIDS cases have resulted from human T-lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) exposure up to 7 years before diagnosis. Prospective studies of the incidence and prevalence of HTLV-III/LAV infection should determine whether current reports of patients who meet the CDC case definition for AIDS accurately reflect the distribution of infected persons.