HIV and STI prevalence
Estimated prevalence of HIV and STIs among IDUs in four cities are shown in Table 2. The prevalence of HIV was 52.4% (range 42.8- 56.0%). Prevalence of syphilis, gonorrhoea and chlamydia was low across cities. HIV prevalence was 27.0% among the 33 IDUs injecting for less than one year, 35.4% among those (n = 303) injecting for one to three years and 61.0% among those (n = 670) injecting for longer than three years (p