Objective: To assess recent developments in the HIV epidemic in injecting drug users (IDUs) in New York City. With >50,000 cases of AIDS in IDUs, New York has experienced the largest HIV/AIDS epidemic in IDUs of any city in the world.
Methods: Serial cross-sectional surveys conducted continuously from 1990 to 2001 of IDUs entering the Beth Israel Medical Center (BIMC) drug detoxification program in New York City. HIV serostatus, use of prevention services, and risk behaviors were measured. Individuals were permitted to participate multiple times in the surveys but not more than once in any year.
Results: Two thousand eight hundred eighty-seven individuals contributed 3100 observations from 1990 to 2001. There was a substantial and consistent decline in the prevalence of HIV infection among IDUs entering the BIMC detoxification program, from 54% (165/304) in 1991 to 13% (39/303) in 2001 (P < 0.0001). The decline was highly linear, with r2 = 0.92 and a slope of -3.7% in seroprevalence per year. The decline occurred for both males and females, both short and long-term IDUs, and the three largest racial/ethnic subgroups (all P < 0.001 by Cochran-Armitage testing). Use of HIV prevention services increased substantially, particularly syringe exchange and voluntary HIV counseling and testing. General reductions in injection risk behaviors occurred, but substantial numbers of IDUs continued to engage in both receptive and distributive syringe sharing. Two conditional types of risk reduction not currently recommended by health authorities were reported: informed altruism, in which persons who knew that they were HIV seropositive reduced transmission behavior, and partner restriction, in which persons who shared needles and syringes primarily confined this sharing within small social networks.
Conclusions: HIV infection continues to decline in this population of IDUs in New York City, suggesting the possibility of bringing very high prevalence epidemics under control. Risk elimination may not be required; rather, multiple forms of risk reduction may be effective in reducing HIV transmission within a local population of IDUs.
HIV infection has been described in injecting drug users (IDUs) in >100 countries throughout the world. 1 In parts of eastern Europe, Russia, central Asia, and China, HIV is spreading quite rapidly among IDUs, with an incidence of ≥20% per year and a prevalence ≥70%. 2 IDUs form the leading edge of the HIV epidemic in many of these areas, with the possibility for further HIV spread from IDUs to the larger non-drug-injecting population.
Effective interventions to reduce HIV transmission among IDUs include increased access to sterile injection equipment (through syringe exchange and/or pharmacy sales), community-based outreach, and long-term drug abuse treatment. 3 When these interventions are applied early and on a large scale, it is possible to contain HIV transmission at very low levels (<1% per year) and avert HIV epidemics in local populations of IDUs. 4-6
If the prevalence of HIV infection reaches a high level (≥30%) among a large population of IDUs, however, reducing continuing transmission becomes much more difficult. With a large number of HIV-infected IDUs who can transmit the virus, even modest levels of continuing risk behavior can perpetuate unacceptably high incidence. For example, the incidence of HIV infection among IDUs is ∼3% per year in Amsterdam, 7 6% per year in Bangkok, 8 and 3-5% per year in Vancouver, British Columbia, Canada. 9 Reducing HIV transmission after high seroprevalence levels have been reached among large IDU populations remains a major challenge in HIV epidemiology and prevention research.
We report trends in the prevalence of HIV infection, use of prevention services, and risk behavior among IDUs in New York City for the last decade (1990-2001). New York City experienced the first, and to date the largest, HIV epidemic in IDUs of any city in the world. 10 New York City also served as the epicenter for the spread of HIV along the East Coast 11,12 and throughout the United States as a whole. 13 The virus spread rapidly among IDUs during the late 1970s, and the prevalence of HIV infection then stabilized at ∼50% from the middle 1980s through the early 1990s. The incidence of HIV infection was estimated to be ∼13 cases per 100 personyears during the period of rapid spread 10 and 4-5 cases per 100 person-years during the period of stable high prevalence. 14 From 1990 to 1996, there were declines in the prevalence, incidence, and injection risk behavior of HIV infection. 15,16 As reported here, from 1997 to 2001, the decline in the prevalence of HIV infection continued but with a different pattern of risk reduction. The recent reductions in risk behavior do not reflect only a simple risk reduction (less sharing of needles and syringes) but may also reflect forms of risk reduction that are not currently recommended by health authorities.