Objective: Determine the incidence of hepatitis C virus antibodies among a cohort of prisoners.
Design: Follow-up study of a random sample of prisoners who participated in a cross-sectional survey in 1996.
Setting: 29 correctional centres in New South Wales (Australia).
Participants: 181 adult prisoners (163 men and 18 women).
Results: The incidence of hepatitis C virus antibody among the 90 inmates who were seronegative at the first test in 1996 was 7.1 per 100 person-years (16 seroconverters). Among the 90 inmates, 37 had re-entered the prison system following release into the community and 53 had been continuously detained. The seroconversion rate was higher among the re-entrants compared with those who had been continuously incarcerated (10.8 vs. 4.5 per 100 person-years, p=0.07). However, when the data was stratified by injecting status, the serocon-version rate in the two groups was similar. Most of the seroconverters had histories of injecting drug users (14/16). The overall incidence among injectors was 19.3 per 100 person years (95% CI: 9.1-29.2).
Conclusions: Hepatitis C transmission occurs inside the prison with injecting drug use the likely cause. Among non-injectors, tattooing was the most likely mode of transmission. Harm minimisation measures with proven effectiveness need to be considered for this environment.