Sharing of needles among users of intravenous drugs.
D000163:Acquired Immunodeficiency Syndrome / Q000635:transmission*; D004866:Equipment Contamination; D006266:Health Education; D006801:Humans; D007275:Injections, Intravenous / Q000295:instrumentation; D008297:Male; D009339:Needles; D019966:Substance-Related Disorders