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The Second 100,000 Cases of Acquired Immunodeficiency Syndrome -- United States, June 1981-December 1991

The first cases of acquired immunodeficiency syndrome (AIDS) were reported in June 1981 (1). From 1981 through December 1987, 50,000 AIDS cases had been reported to CDC, and by August 1989, 100,000 cases had been reported (2). From September 1989 through November 1991, state and territorial health departments reported 100,000 additional cases. By December 31, 1991, a cumulative total of 206,392 cases had been reported (Figure 1), and the cumulative number of reported deaths associated with AIDS was 133,232. This report presents characteristics of the first and second 100,000 persons with AIDS.

Overall, most reported AIDS cases occurred among homosexual/bisexual men (i.e., men who reported sexual contact with other men) (59%) and injecting-drug users (IDUs) (22%). Of the first 100,000 reported AIDS cases, 61% occurred among homosexual/bisexual men with no history of IDU, and 20%, among female or heterosexual male IDUs. In comparison, of the second 100,000 reported cases, 55% occurred among homosexual/bisexual men with no history of IDU, and 24% occurred among female or heterosexual male IDUs.

The second 100,000 cases reflect an increasing proportion of persons with AIDS who have been reported to have had heterosexual exposure to persons at risk for human immunodeficiency virus (HIV) infection. Of the first 100,000 persons with AIDS, 5% were attributed to heterosexual transmission, compared with 7% among the second 100,000--a 44% increase. Of all AIDS cases among women, 34% were attributed to heterosexual transmission, and women accounted for 61% of all cases attributed to heterosexual transmission. Of the first 100,000 persons with AIDS, 9% were women, compared with 12% of the second 100,000 persons. The first 100,000 persons with AIDS included 1683 children, of whom 81% were born to mothers with or at risk for HIV infection; the second 100,000 persons with AIDS included 1702 children, of whom 87% were born to mothers with or at risk for HIV infection.

A disproportionate number of AIDS cases continue to be reported among blacks and Hispanics. Of the first 100,000 reported cases, 27% occurred among blacks and 15% among Hispanics; of the second 100,000 reported cases, these proportions increased to 31% and 17% for blacks and Hispanics, respectively.

The proportion of AIDS cases related to transfusions as a mode of exposure declined in both adults (2.5% to 1.9%) and children (11% to 5.6%) from the first to the second 100,000 cases. Reported by: Surveillance Br, Div of HIV/AIDS, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The cumulative total of more than 200,000 reported AIDS cases emphasizes the rapidly increasing magnitude of the HIV epidemic in the United States. The first 100,000 cases were reported during an 8-year period, whereas the second 100,000 cases were reported during a 2-year period.

The number and proportion of AIDS cases associated with heterosexual transmission of HIV has been increasing steadily. Factors associated with an increased risk for heterosexual transmission include multiple sex partners and the presence of other sexually transmitted diseases. In the United States, men and women who have unprotected sexual contact, particularly with partners known to have risks for HIV infection, are at increased risk for HIV infection. A recent analysis of expected trends in AIDS cases in the United States suggests that by 1995, the infection rate among nondrug-using heterosexual men and women may be associated with a doubling of AIDS cases acquired through heterosexual transmission (3).

Of the estimated 1 million HIV-infected persons in the United States, approximately 20% have developed AIDS. Approximately half of all persons who have been diagnosed with HIV infection and who have evidence of severe immunosuppression (i.e., CD4+ counts less than 200 cells/uL) meet the current AIDS surveillance case definition (4). Approximately 125,000 persons who do not have an AIDS-defining illness are estimated to have a CD4+ lymphocyte count less than 200 cells/uL (CDC, unpublished data). CDC has proposed expanding the AIDS surveillance case definition to facilitate more complete reporting of all persons with severe HIV-related immunosuppression and who are at the highest risk for developing serious illnesses or death* (5).


  1. CDC. Pneumocystis pneumonia--Los Angeles. MMWR 1981;30:250-2.

  2. CDC. First 100,000 cases of acquired immunodeficiency syndrome--United States. MMWR 1989;38:561-3.

  3. Brookmeyer R. Reconstruction and future trends of the AIDS epidemic in the United States. Science 1991;253:37-42.

  4. Farizo KM, Buehler JW, Berkelman RL. Leading non-AIDS defining systemic infections in HIV-infected persons (Abstract). In: Program and abstracts of the 119th annual meeting of the American Public Health Association. Washington, DC: American Public Health Association, 1991:107.

  5. CDC. Extension of public comment period for revision of HIV infection classification system and expansion of AIDS surveillance case definition. MMWR 1991;40:891.

    • The draft document is available for review from the National AIDS

    Clearinghouse, P.O. Box 6003, Rockville, MD 20849-6003; telephone (800) 458-5231. Written comments on this draft document should be sent to the same address by February 14, 1992.

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