AIDS among persons aged > or = 50 years--United States, 1991-1996.

Early in the human immunodeficiency virus (HIV) epidemic, infection occurred disproportionately among older persons as a result of transmission through receipt of contaminated blood or blood products. Through 1989, receipt of contaminated blood or blood products accounted for only 1% of cases among persons aged 13-49 years; in comparison, this risk factor accounted for 6%, 28%, and 64% of cases among persons aged 50-59 years, 60-69 years, and > or =70 years, respectively. Because of implementation of voluntary donor deferral and routine screening of blood donations in 1985, the number and proportion of acquired immunodeficiency syndrome (AIDS) cases associated with this risk factor decreased among persons aged > or =50 years. However, among persons aged > or =50 years, the number and proportion with AIDS associated with other modes of exposure increased. This report describes the characteristics of persons aged > or =50 years with AIDS reported during 1996 and presents trends in the incidence of AIDS-opportunistic illnesses (AIDS-OIs) diagnosed during 1991-1996 by mode of HIV exposure for persons aged > or =50 years. The findings indicate that, even though the incidence of AIDS-OIs during 1996 was higher among persons aged 13-49 years (89%), the proportion of AIDS-OIs accounted for by those aged > or =50 years (11%) was substantial.