HIV infection among intravenous drug users: epidemiology and risk reduction

Abstract

Research on the epidemiology of HIV infection among IV drug users is still at a relatively early stage. Multilocation studies that would permit better geographic comparisons are greatly needed. Multi-method studies within single geographic areas are also needed to assess possible biases with respect to sample recruitment and data collection procedures. The continuation of the epidemic provides a changing historical context that complicates any comparisons. Despite these problems, there are some consistencies that can be seen across studies. Studies of HIV seroprevalence among IV drug users show wide variation among cities in the United States and Europe. The time that the virus was introduced into the IV drug using group within the city is one factor in explaining these differences; other cross-city factors have yet to be identified. Once HIV has been introduced into the IV drug use group within a particular geographic area, there is the possibility of rapid spread up to seroprevalence levels of 50% or greater. Thus, a currently low seroprevalence rate should not be seen as a stable situation. Frequency of injection and sharing of equipment with multiple other drug users (particularly at shooting galleries) have been frequently associated with HIV exposure. Being female, ethnicity (in the USA) and engaging in prostitution also may be associated with increased risk for HIV exposure, suggesting that prevention programs should include special consideration of sex and ethnic differences. Studies of AIDS risk reduction show that substantial proportions of IV drug users are changing their behavior to avoid exposure to HIV. This risk reduction is probably more advanced in New York, with its high seroprevalence and incidence of cases, but is also occurring in cities with lower seroprevalence and limited numbers of cases. The primary forms of risk reduction are increasing the use of sterile equipment, reducing the number of needle sharing partners, and reducing the frequency of injection. These behavior changes are very similar to the frequently identified behavioral risk factors associated with HIV exposure, suggesting that they should be effective in at least slowing the spread of HIV among IV drug users. No linkage of risk reduction to decreases in seroconversion has yet been shown, however, and greater risk reduction is clearly required. A variety of prevention strategies will probably be needed to reduce the spread of HIV among IV drug users. Prevention of initiation into drug injection is an undeniable long-term goal for the control of HIV infection, but there is very little research being conducted in this area.

PIP: Published and unpublished reports on HIV seroprevalence and risk reduction among IV drug users (IVDU) are reviewed as of 1986. The seroprevalence of HIV among IVDUs varies widely by location, often with a north-south gradient. The strongest indicator of prevalence is the date of introduction of HIV, with rates as high as 50% appearing within 2 years. The behavioral risk factors are sharing injection equipment partners, using shooting galleries, being a female prostitute or a member of a minority ethnic group. There are no data yet on whether removing barriers to sterile syringes and needles or needle exchange programs is effective in cutting the spread of HIV. There are some hints that IVDUs are capable of altering risky behavior. Surveys of 2 groups of methadone maintenance client suggest increased knowledge of HIV risks and increased use of clean needles. It is reported that the black market for needles in New York City has shown increased sales, that sales of syringes with extra needles are popular, that heroin sellers are including sterile syringes with bags, and even that re-packaged used unsterile needles are enjoying a brisk profit on the street. There are suggestions that IVDUs in Amsterdam and San Francisco are altering their high risk behaviors. Data from Amsterdam shows that IVDUs have not increased their frequency of injection nor reduced their demand for drug treatment as a result of the needle exchange program. Possible prevention strategies are education of people before they initiate IV drug use; provision of ample drug treatment as a cost effective means of reducing the expense of treating AIDS patients; and providing sterile needles or teaching IVDUs how to clean syringes and needles. Probably a mixed strategy will be to reduce the risk of HIV or IVDUs.