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U.S. Department of Health and Human Services

Archival Content: 1999-2005

A Comprehensive Approach:
Preventing Blood-Borne Infections Among Injection Drug Users

Chapter 1: Key Ideas

  • Injection drug use is a major force in the epidemics of HIV and viral hepatitis.

  • More than one-third of AIDS cases are directly or indirectly associated with injection drug use.

  • IDUs become infected and transmit the virus through high-risk drug use and sexual behaviors.

  • Understanding the social contexts in which high-risk drug use and sexual behaviors take place is crucial to planning and carrying out effective interventions.


Since 1981, 733,374 cases of AIDS have been reported to the CDC (CDC, 1999a). At least 430,441 of these Americans have died. It is estimated that 650,000 to 900,000 Americans are now living with HIV, and that approximately 40,000 new infections occur each year (CDC, 1999b). HIV infection and AIDS is concentrated in large urban are as, primarily along the East and West Coasts, in the south, and in Puerto Rico. In the late 1980s and early 1990s, AIDS incidence increased in all regions of the country, with the most dramatic increases in the South. Since then, incidence has declined in all regions except the South, where it has remained stable (CDC, 1999b). CDC surveillance data show that injection drug use is directly or indirectly associated with about one-third of all AIDS cases (CDC, 1999a).

Of the 46,400 new cases of AIDS reported in 1999, almost 14,000 were IDU-associated:

  • 7,207, or 52 percent of these IDU-associated cases, were heterosexual male IDUs;
  • 2,931, or 21 percent, were female IDUs;
  • 1,806, or 13 percent, were men who have sex with men and were IDUs;
  • 1,790, or, 13 percent, were heterosexual sex partners of IDUs; and
  • 99, or less than 1 percent, were children whose mothers were IDUs or the sex partners of IDUs.

These numbers for IDU-associated AIDS cases in 1999 are minimum estimates, as 11,209 of the 46,400 cases (24 percent) were classified as "other/risk not reported or identified." Some of these cases were IDU-associated.

Data from prevalence surveys and case surveillance continue to demonstrate the heavy impact of the HIV/AIDS epidemic on racial and ethnic minority populations and on women, youth, and children. The data suggest three inter related issues play a role in this-disparities in socioeconomic status, the nation's inability to substantially reduce substance abuse, and the intersection of substance abuse and the epidemics of HIV and other STDs. There is no question that drug use plays a major role in the spread of the epidemic of HIV and other blood-borne infections among African Americans and Hispanics, both through the direct impact of injection drug use and indirectly through sex with an IDU or through the exchange of sex for drugs or money (CDC, 1999a; CDC, 1999b). In 1998, IDU-associated AIDS cases represented almost 40 percent of all cases among African Americans and 43 percent of all cases among Hispanics (CDC, 1999b). In 1998, the IDU-associated infection rate was five times higher among Hispanics than among whites and more than ten times higher among African Americans than among whites (CDC, 1999c). Within these continuing high numbers, however, there appear to be some promising trends. Partly because of prevention efforts targeting those at highest risk, the epidemic has slowed considerably since its earliest days (CDC, 1999b). HIV seroincidence in injection drug users has declined over the past several years in the largest drug- using communities, including New York, northern New Jersey, and Los Angeles (Des Jarlais etal., 2000; Holmberg, 1996). These declines can be attributed to changes in IDUs' risk behaviors, including greater use of sterile needles, more disinfection of drug preparation equipment, shifts from injection to snorting, and stopping using drugs.

Injection drug use The shift from injecting to snorting drugs is documented by information on drug use trends gathered by the National Institute on Drug Abuse's (NIDA) Community Epidemiology Work Group (CEWG, 1998). CEWG contributors report that although heroin use indicators continue to increase in 12 cities monitored by CEWG, in those cities in which high-purity white powder heroin is available, heroin snorting has become much more prevalent and is spreading to new and younger users. However, this may be a short-lived trend, as many of these snorters may shift to injecting if the purity of available heroin drops. It is also known that many drug users who begin by snorting heroin eventually move to injecting it (Irwin et al., 1996).

The findings on declining seroprevalence have been supported by other recent work, including an examination of temporal trends in HIV seroprevalence in New York from 1991 to 1996 (Des Jarlais et al., 1998). New York has between 170,000 to over 200,000 IDUs and almost 50,000 cases of diagnosed AIDS among IDUs and their partners and children (Des Jarlais et al., 1998). New York City accounts for almost one-fourth of the IDU AIDS cases in the U.S. and almost one-tenth of all AIDS cases in the U.S. During the first half of the 1990s, the city saw a steady decline in HIV seroprevalence. The authors attribute the decline in number of seropositive IDUs to two major factors. The first is the death of many HIV-positive IDUs who became infected early in the epidemic. Others may have become too ill to engage in the activities needed to obtain and use drugs. The second factor is the adoption of risk reduction behaviors as a result of community out-reach efforts, syringe exchange programs, and other contributing factors.

idu-ta The transmission of other blood-borne diseases, primarily hepatitis B and hepatitis C, through unsafe sex and sharing needles, syringes, and drug preparation equipment, such as filters, water, and cookers, is another important concern for public health agencies and service providers. Approximately 1 to 1.25 million Americans are chronically infected with hepatitis B virus (HBV), and since 1995, approximately 185,000 new infections have occured each year. The CDC reports that the incidence of HBV infection increased through the mid-1980s, then declined through 1994. A small portion of this decline is attributed to the wider use of vaccine among healthcare workers. It is hypothesized that a significant portion of this decline was the result of reduced high-risk practices following the introduction of HIV prevention messages.

An estimated 2.7 million Americans are chronically infected with hepatitis C. Most are unaware of their infection because some individuals experience no symptoms for 20-30 years after infection (Alter et al., 1999). However, hepatitis C is a major cause of cirrhosis and liver cancer, and HCV-related end-stage liver disease is the leading reason for liver transplantation in the U.S. The estimated annual incidence of hepatitis C remained relatively stable through much of the 1980s. However, based on sentinel surveillance for acute viral hepatitis conducted in four U.S. counties, the CDC estimates that the average number of newly acquired HCV infections has declined from 180,000 in 1984 to 40,000 in 1998 (Alter and Moyer 1998, CDC unpublished data). The risk of exposure to HCV from transfused blood has declined dramatically in recent years with improvements in screening blood donations. In contrast, illegal drug use currently accounts for about 60 percent of HCV transmission, while sexual exposures account for 20 percent (Alter, 1999). Studies have consistently shown that injection drug use is the single most important risk factor for hepatitis C virus infection (Alter et al., 1999; Alter and Moyer, 1998; Garfein et al., 1998; Thomas et al., 1995). Among IDUs, hepatitis C virus infection is extremely prevalent-in studies conducted worldwide, from 50 to 95 percent of IDUs are infected (Garfein et al., 1998). This high prevalence persists even in populations in which the prevalence of HIV is relatively low (van Beek et al., 1998). This may be because HCV has a higher average transmission efficiency than does HIV (Coutinho, 1998; Crofts et al., 2000). In addition, HIV may be transmitted on equipment such as swabs, spoons, and rinse water that may be commonly shared by IDUs even if they do not share syringes1 (Coutinho, 1998; Crofts et al., 2000). Another reason why HCV is of particular concern is that infection appears to be acquired relatively soon after drug injecting is initiated (one study reported that 50 to 80 percent of new IDUs became infected within 6 to 12 months of first injecting [Garfein et al., 1996]). However, more recent studies are suggesting that IDUs are getting infected at a slower rate (Garfein et al., 2000). There is however a very large reservoir of potentially infectious individuals, which provides multiple opportunities for transmission to occur (Alter and Moyer, 1998).

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