Acquired Immunodeficiency Syndrome -- United States, 1992

During 1992, state and territorial health departments reported 47,095 cases of acquired immunodeficiency syndrome (AIDS) to CDC, an increase of 3.5% over the 45,499 cases reported in 1991. As in previous years, most (50.8%) cases were attributable to transmission of human immunodeficiency virus (HIV) among homosexual/bisexual men (Table 1). This report summarizes the characteristics of persons reported with AIDS in 1992, compares them with data from 1991 (Table 1), and describes selected trends since 1988. *

From 1991 through 1992, larger proportionate increases in reported cases occurred among women (9.8%) than among men (2.5%). For women, rates were higher for non-Hispanic blacks and Hispanics (31.3 and 14.6 per 100,000 population, respectively) than for non-Hispanic whites (1.8). Ten metropolitan statistical areas ** accounted for more than half (51.5%) of reported cases among women (Table 2).

The number of reported cases among homosexual/bisexual men decreased during 1992, sustaining a trend noted first in 1991 (1); the number of cases attributable to injecting-drug use (IDU) increased slightly, representing nearly one fourth of reported cases. Heterosexual contact accounted for the largest proportionate increase (17.1%) in reported cases. The proportionate increase in cases attributed to heterosexual contact was greater for men (26.3%) than for women (11.5%); however, women accounted for most persons infected through heterosexual contact (59.4%). The second largest proportionate increase was in perinatal transmission (13.4%).

Because cases reported in a year may have been diagnosed in earlier years, long-term trends in the occurrence of AIDS are reflected more accurately by analyses based on year of diagnosis with adjustment for reporting delays (2). From 1988 through 1991, the number of cases diagnosed among women infected through IDU exceeded those among women infected through heterosexual contact. However, in 1992, the number of AIDS cases among women infected through heterosexual contact exceeded those infected through IDU for the first time (Figure 1). This pattern varied by region: IDU was the predominant mode of transmission among women in the Northeast ***; however, heterosexual transmission equaled or surpassed IDU among women in the South ****, the Midwest *****, the West ******, and the U.S. territories. Among those cases attributed to heterosexual transmission, most (56.8%) involved sex with an injecting-drug user.

Heterosexual transmission accounted for a greater proportion of AIDS cases among women aged 20-29 years than among women aged greater than or equal to 30 years (60.0% and 46.5%, respectively). The annual number of cases diagnosed among all persons aged 20-29 years increased by 15.5% since 1988; however, the annual number of women aged 20-29 years with heterosexually acquired AIDS increased by 96.7% since 1988. This trend primarily reflects a larger increase among non-Hispanic black women than among non-Hispanic whites and Hispanic women (Figure 2). In addition, the greatest increase among women aged 20-29 years with heterosexually acquired AIDS was in the South (165.5% since 1988).

Reported by: Local, state, and territorial health depts. Div of HIV/AIDS, National Center for Infectious Diseases, CDC.

Editorial Note

Editorial Note: The findings in this report reflect the evolving nature of the HIV epidemic in the United States, which is a composite of multiple epidemics in different regions and among different population subgroups. During 1992, the rate of increase in AIDS cases was again higher for women than for men, and heterosexual contact became the predominant mode of HIV exposure among women in whom AIDS was diagnosed; most heterosexual transmission occurred among women who were sex partners of injecting-drug users. The increase in AIDS among women is reflected by an increase in cases among infants and children aged 0-4 years, most (95.8%) of whom were infected perinatally.

The increase in cases among women aged 20-29 years primarily reflects persons who were infected as adolescents. Many adolescents, like adults, practice behaviors that increase their risk for HIV infection (3). However, even though adolescents have adequate levels of knowledge about AIDS (4), they may be particularly resistant to behavior change because of feelings of invulnerability that are characteristic of adolescence. Developing and implementing educational programs specific to adolescents should remain a high priority.

Because race and ethnicity are likely risk markers and not risk factors for HIV infection, these markers may assist in identifying groups at highest risk for HIV infection and targeting prevention efforts. The higher incidence of AIDS among non-Hispanic blacks and Hispanics than among non-Hispanic whites probably reflects a combination of such risk factors, including socioeconomic status and access to medical care.

Because of the hierarchical classification of risk (5), and because risk information may not always be complete or verified, AIDS surveillance probably approximates the actual frequency of heterosexual transmission. During 1992, 10.2% of men and 23.5% of women who reported IDU also reported heterosexual contact with a person at risk. Therefore, some of these persons may have acquired HIV through heterosexual contact. Conversely, some persons with AIDS attributed to heterosexual contact may have other unreported or undetermined risk factors (6).

The steady increase in heterosexually acquired AIDS cases among men and women underscores the need to improve understanding of factors that influence the adoption of safer sexual practices among heterosexuals and how these factors vary in different population subgroups. Although some surveys have documented reduced number of sex partners among high school students and persons who attend sexually transmitted diseases clinics (7,8), a survey of the general heterosexual population (9) found low rates of condom use for persons with multiple partners and for persons with partners at risk for HIV infection, indicating that behavioral changes sufficient to decrease HIV transmission may not yet have occurred.

The findings in this report indicate that the number of AIDS cases attributed to male-to-male sexual transmission has decreased slightly, and the proportionate increase in cases attributed to IDU was less than that in cases attributed to heterosexual contact. However, because injecting-drug users and men who have sex with men continue to account for 80.3% of AIDS cases, prevention efforts that target these populations must remain a high priority while interventions targeted at persons at increased risk for heterosexual transmission are strengthened.

References

1. CDC. Update: acquired immunodeficiency syndrome -- United States, 1991. MMWR 1992;41:463-8.

2. Karon JM, Devine OJ, Morgan WM. Predicting AIDS incidence by extrapolating from recent trends. In: Castielo-Chavez C, ed. Mathematical and statistical approaches to AIDS epidemiology: lecture notes in biomathematics. Vol 83. Berlin: Springer-Verlag, 1989.

3. CDC. Selected behaviors that increase risk for HIV infection, other sexually transmitted diseases, and unintended pregnancy among high school students -- United States, 1991. MMWR 1992;41:945-50.

4. Diclemente RJ, Lanier MM, Horan PF, Lodico M. Comparison of AIDS attitudes and behaviors among incarcerated adolescents and a public school sample in San Francisco. Am J Public Health 1991;81:628-30.

5. CDC. HIV/AIDS surveillance report. Atlanta: US Department of Health and Human Services, Public Health Service, May 1993:18-9.

6. Nwanyanwu OC, Conti L, Ciesielski CA, et al. Increasing frequency of heterosexually transmitted AIDS in southern Florida: artifact or reality? Am J Public Health 1993;83:571-3.

7. CDC. HIV instruction and selected HIV-risk behaviors among high school students -- United States, 1989-1991. MMWR 1992;41:866-8.

8. CDC. Sexual risk behaviors of STD clinic patients before and after Earvin "Magic" Johnson's HIV-infection announcement -- Maryland, 1991-1992. MMWR 1993;42:45-8.

9. Catania JA, Coates TJ, Stall R, et al. Prevalence of AIDS-related risk factors and condom use in the United States. Science 1992;258:1101-6.

* Single copies of this report will be available free until July 23, 1994, from the CDC National AIDS Clearinghouse, P.O. Box 6003, Rockville, MD 20849-6003; telephone (800) 458-5231. 

** Metropolitan statistical areas typically include the main city as well as the surrounding urban and suburban areas. 

*** New England and Middle Atlantic regions. 

**** South Atlantic, East South Central, and West South Central regions. 

***** East North Central and West North Central regions. 

****** Mountain and Pacific regions.

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