Faculty Bibliography

There is strong epidemiologic evidence from studies of i.v. drug users in New York City for the existence of one or more gender-related cofactors in response to HIV infection. The strength of the evidence comes from the variety of data sets that indicate a gender-related cofactor and from the consistency of the pattern found: in all of the data sets, females appear to have a more "favorable" response than do males. The extent of underrepresentation of females in the cases of AIDS in i.v. drug users--a possible 35% reduction in the development of clinical AIDS-suggests that such a cofactor should be considered of practical importance. Identifying the mechanism(s) for a gender difference may lead to ways of deliberately affecting the course of the infection. Further research on the gender difference may also contribute to our understanding of interactions among the various components of the immune system and the interaction of the immune system with other behavioral and physiologic systems.

As the second largest group of persons to have been infected with human immunodeficiency virus (HIV), and the most likely to transmit HIV to heterosexual partners in the United States and Europe, iv drug users will play an increasingly important role in the future of the AIDS epidemic. This paper reviews five emerging critical issues regarding HIV infection among iv drug users. In epidemiology, rates of drug injection and anonymous sharing of injection equipment appear related to rapid spread of HIV among iv drug users, while heterosexual transmission from iv drug users appears to have been occurring at a relatively slow but constant rate. Data exist that support a gender-related cofactor and a continuing drug injection cofactor, but mechanisms for these potential cofactors have not been determined. Besides frank AIDS, HIV infection also appears to lead to epidemic-level increases in a variety of fatal infections among iv drug users. Several studies of prevention show active risk reduction among iv drug users, but new methods are urgently needed to increase amount of risk reduction.

There is now evidence from a wide variety of geographic areas that many intravenous drug users will change their behavior in order to reduce their risk of developing AIDS. There is even evidence from some areas that the behavior change has led to relative stabilization of seroprevalence rates, although longer-term studies will be needed to establish this definitively. AIDS behavior change in the area of sexual risk reduction appears to be much more difficult than change of drug injection behavior. Conceptual models of AIDS-related behavior change are needed, particularly models that can incorporate the injection of different drugs and variation in social and psychological characteristics among drug injectors. There is increasing evidence for a wider spectrum of HIV-related morbidity and mortality among intravenous drug users than is captured by the current surveillance definition for AIDS, again emphasizing the need for effective prevention programs.

Intravenous drug use continues as the second most common risk behavior associated with acquired immune deficiency syndrome (AIDS) in the United States and Europe. Recently there has been increased public and research attention to this problem. Five areas of public health concern for AIDS among i.v. drug users are identified and discussed: (a) the potential spread of human immunodeficiency virus (HIV) to drug users in developing countries; (b) the emergence of cocaine use associated with HIV infection; (c) ethnic differences in seroprevalence rates among i.v. drug users, with ethnic minorities tending to have higher rates; (d) difficulties in changing the sexual behavior of i.v. drug users; and (e) an increased frequency of fatal infections among HIV seropositive drug users that are not counted with the current surveillance definition of AIDS. There have been numerous studies of AIDS risk reduction among i.v. drug users, but the ultimate effect of the behavior change on spread of the virus is not yet clear. Preliminary studies from New York City, San Francisco, and Stockholm indicate a relative stabilization of seroprevalence in those cities, suggesting that the behavior changes reported in those cities may be significantly slowing the rate of viral spread.