Syringe exchange programs: lowering the transmission of syringe-borne diseases and beyond.

OBJECTIVE: This chapter attempts to describe the factors influencing the transmission of syringe-born viruses, to review the effects of syringe exchange programs (SEPs) in terms of these factors, and to explore the gamut of health-promoting activities of SEPs.
RESULTS: The chapter is divided into six sections: biological factors in syringe-borne viral transmission, behavior and viral transmission, quantifying viral transmission, preventing viral transmission, impediments to preventing viral transmission, and research for preventing viral transmission. Understanding how biological and behavioral factors influence transmission of human immunodeficiency virus (HIV) and hepatitis builds a framework to investigate the epidemiology and the impact of SEPs on disease transmission. Even under circumstances in which these programs do not appear to be effective, understanding the implications of the biological and behavioral factors can contribute to our understanding of program benefits and limitations. Furthermore, program benefits may not be restricted to direct effects on disease transmission. Many programs offer services to drug injectors that include risk reduction training, facilitated entry into substance abuse treatment, and medical care.
CONCLUSIONS: SEPs can reduce the transmission of syringe-borne viruses without increasing illicit drug use. However, lack of resources, acceptance, and consequently, protection of many of those at risk when they are most vulnerable have hampered program effectiveness. New studies need to be designed to explicate the full measure of program benefit within covered communities and identify the means by which SEPs can expand benefit to individuals at greatest risk.