This thesis provides a synthesised analysis of the prevalence of blood borne viral infections and their determinants in the Irish prisoner population, both entrants (committal) and inmates (census). In the census survey anti-HBc prevalence was 8.7% (95% CI 7.2 to 10.5), anti-HCV was 37% (95% CI 34.3 to 39.9) and anti-HIV 2% (95% CI 1.3% to 3%).

The most important predictor of antibody positivity for hepatitis B and hepatitis C was a history of injecting drug use (anti-HBc adjusted OR 22, anti-HCV adjusted OR 81). 42.4% of male respondents and 59.7% of female respondents reported ever injecting drugs. 20.8% of 501 injecting drug users reported first injecting in prison. 70.5% of injectors reported sharing needles in prison. Men reporting anal sex with other men was an important risk factor for testing positive for anti-HIV (adjusted OR 8). In the committal survey, the prevalence of anti-HBc was 6% (95% CI 4% to 9%), of anti-HCV was 22% (95% CI 19% to 25%) and anti-HIV was 2% (95% CI 1% to 4%). One third of the respondents had never previously been in prison (197); these had the lowest prevalence of anti-HBc (2%), of anti-HCV (3%) and of anti-HIV (0%). 29% of the 593 respondents reported a history of injecting drug use.

Only 7% (14/197) of those entering prison for the first time reported ever injecting drugs compared to 40% (157/394) of those previously in prison. Injecting drug use was the most important predictor of anti-HBc (adjusted OR 16) and anti-HCV (adjusted OR 89).