Research on Preventing HIV/AIDS and Other Infections in Drug-Using
Epidemiology of Risk Behaviors
Reusing and sharing syringes, needles, and other drug injection equipment exposes injecting drug users (IDUs) to the risk of contracting or transmitting HIV and other blood-borne infections (e.g., hepatitis B (HBV) and hepatitis C (HCV). In addition to injecting drug use, unprotected sexual contact with infected individuals is a major way that these and other sexually transmitted diseases (STDs) are transmitted.
During the course of the HIV/AIDS epidemic, the major groups at risk for HIV in the United States have been men who have had sex with men, IDUs, the sexual partners of IDUs, and people who have blood transfusions. Today, however, the boundaries between the major risk groups are less distinct. Considerable mixing occurs among different at-risk populations who engage in multiple types of drug use, high-risk needle practices, and unsafe sex. A disproportionate number of HIV/AIDS cases, most of which are associated with injecting drug use, have occurred among racial and ethnic minority populations of both genders. These changes reflect the dynamic interactions of the epidemic and simultaneous risk-taking behaviors, including injecting and non-injecting drug use, unprotected sex with multiple partners, and the exchange of sex for drugs or money (1).
Prevalence rates have been reported as high as 50 percent for hepatitis B virus and 65 percent for hepatitis C virus among people who have injected drugs for less than a year.
IDUs have one of the highest HBV incidence rates among all risk groups, and at least half of all new HCV cases occur among IDUs. Studies have shown that infection with HBV and HCV frequently occurs soon after an individual begins injecting drugs. Prevalence rates vary considerably, but have been reported as high as 50 percent for HBV and 65 percent for HCV among people who have injected drugs for less than a year. Co-infections of HBV, HCV, and HIV have been found to cluster in IDUs and, in some geographic regions, are endemic among long-term IDUs. HCV is now considered an opportunistic infection in HIV-positive people, according to the U.S. Public Health Service and the Infectious Diseases Society of America (2). Although a vaccine is not yet available for HIV or HCV, data on the HBV vaccine indicate that it is possible to immunize injecting and non-injecting drug users successfully.
The strong epidemiologic association between HIV and other STDs also has been recognized since the HIV/AIDS epidemic began. Some studies have reported a two- to five-fold increased risk for HIV among people who have other STDs (3). Shifts in the HIV/AIDS epidemic in the United States highlight the important cofactor effects of STDs. The notable increase in heterosexual HIV transmission among young women, especially young African-American women, has been linked in part to the disproportionate rate of other STDs in this group (3), as well as to the mixing of drugs (including the non-injecting use of heroin, crack cocaine, amphetamines, and other substances), alcohol, and unprotected sex. Moreover, pregnant women who use drugs or are the sex partners of IDUs risk transmitting one or more infections to their infants. Because the proportion of asymptomatic STDs is higher among women than among men, many women are unaware that they have an infection and do not seek routine screening examinations. Therefore, testing and counseling for HIV and other blood-borne and sexually transmitted infections, including routine screening for asymptomatic STDs, are critically important for controlling, preventing, and treating these infections.
Research Programs on HIV/AIDS Prevention in Drug-Using Populations
NIDA initiated two national multisite intervention programs -- the National AIDS Demonstration Research (NADR) program and the Cooperative Agreement (CA) for HIV/AIDS Community-Based Outreach/Intervention Research Program -- to study the effectiveness of HIV/AIDS prevention approaches among injecting drug users and their sex partners. The NADR program began in 1987. In 1990, NIDA established the CA program, which built on the findings and experiences gained through the NADR program. When crack cocaine emerged in the mid-1980s, it was quickly identified as a major risk factor for unsafe sex, other drug use, and HIV transmission, and the CA program expanded the target population to include non-injecting crack cocaine users.
Community-based outreach was a central intervention strategy in both the NADR and CA programs, and was shown to be a highly effective approach for contacting and engaging out-of-treatment drug users (4). Early in the HIV/AIDS epidemic, a prevailing belief was that IDUs and their sex partners would not or could not modify their behaviors in response to the threat of infection. However, findings from the NADR and CA programs demonstrated that, with
the help of well-designed prevention programs, drug users can stop using drugs, change their risk behaviors, and reduce their risks for acquiring or transmitting the HIV infection (4,5).
Following is a brief overview of each program.
National AIDS Demonstration Research (NADR) Program
The NADR program was conducted from 1987 to 1992 in 29 sites across the United States. The program investigated the effectiveness of outreach-based interventions in reducing HIV risks among out-of-treatment injection drug users and the non-injecting female sex partners of male IDUs. During the study, outreach workers from the local communities were sent to contact members of the target population and begin risk-reduction activities in places where IDUs tend to gather. The outreach workers provided drug users with information on how HIV/AIDS is transmitted, prevented, and treated and materials to reduce risks for infection, such as condoms and bleach kits to disinfect injection equipment. Outreach workers also provided referrals to drug users for locally available services, including drug abuse treatment and medical care for HIV/AIDS. The community-based outreach intervention often included follow-up activities, such as confidential HIV testing and counseling and individual risk assessment.
Cooperative Agreement (CA) Program
The CA program was carried out in 23 sites (21 in the United States, and one each in Puerto Rico and Brazil) from 1990 to 1999. It was designed to advance the knowledge base gained through the NADR program. Successful elements of the NADR program were incorporated into the CA program, and the study design was refined based on its scientific results and insights. Community-based outreach workers contacted out-of-treatment IDUs and crack cocaine users to participate in the intervention. These individuals were assigned to basic or "enhanced" intervention services, but they had access to the same basic services at all study sites. The basic intervention involved community-based outreach as a prelude to two education and counseling sessions. The sessions were organized around optional HIV testing and counseling, which was provided to help drug users learn whether they had tested positive or negative for HIV and what behavioral changes they needed to make to reduce their HIV transmission risks.
- Rothenberg, R.B.; Long, D.; Sterk, C.; Pach, A.; Potterat, J.J.; Muth, S.; and Baldwin, J.A. The Atlanta Urban Network Study: A blueprint for endemic transmission. AIDS 14:2191-2200, 2000.
- Centers for Disease Control and Prevention (CDC). 1999 USPHS/IDSA Guidelines for the Prevention of Opportunistic Infections in Persons Infected with HIV: U.S. Public Health Service (USPHS) and Infectious Diseases Society of America (IDSA). MMWR 48(RR-10), 1999.
- CDC. HIV prevention through early detection and treatment of other sexually transmitted disease - United States recommendations of the advisory committee for HIV and STD prevention. MMWR 47(RR-12):1-24, 1998.
- Coyle, S.L.; Needle, R.H.; and Normand, J. Outreach-based HIV prevention for injecting drug users: A review of published outcome data. Public Health Reports 113(Suppl 1):19-30, 1998.
- Stephens, R.C.; Simpson, D.D.; Coyle, S.L.; McCoy, C.B.; and the National AIDS Research Consortium. Comparative effectiveness of NADR interventions. In: Brown, B.S.; and Beschner, G.M., eds. Handbook on Risk of AIDS. Westport, CT: Greenwood Press, pp. 519-556, 1993.
[Back to top]