Hepatitis C Virus Infection among Male Inmates at Klong Prem Central Prison : Study on Prevalence, Incidence and Risk Factors (อัตราความชุก อุบัติการ และปัจจัยเสี่ยงต่อการติดเชื้อไวรัสตับอักเสบซี ของผู้ต้องขังชายภายในเรือนจำกลางคลองเปรม)

High rate of Hepatitis C Virus (HCV) infection due to intravenous drug use among inmates hasbeen reported worldwide. However, limited information on Thai inmates was available. This studydetermined HCV prevalence, incidence and risk factors of Thai inmates at Klong Prem CentralPrison. A prospective cohort of 689 male inmates was followed for 5 months during 2001-2002.Risk factors and demographic data were obtained by using structured questionnaires and HCV infectionsin blood specimens were tested by ELISA. This study was part of a project on HealthFactors Related to HIV and Other Viral Infection among Inmates, the protocol of which was approvedby the Ethical Review Committee for Research in Human Subjects of the Ministry of PublicHealth of Thailand, 2001. Potential risk factors toward HCV infection were analyzed employingmultiple logistic regression analysis.The rate of HCV infection was 309/689 or 44.85 percent [95% Confidence interval (CI); 41.20-48.57]. After 1,740 person-months, of follow ups, 106 inmates showed HCV seroconversion andthe incidence rate of 6.1 percent person-month [95% CI, Poisson; 5.0-7.4] was observed. By multiplelogistic regression analysis, high HCV infection rate was associated with history of intravenousdrug use (OR = 13.31, p<0.001), ever attending withdrawal clinic prior to incarceration(OR=3.33, p<0.001), tattoos (OR=2.39, p= 0.002) and HIV-1 positive (OR= 17.75, p<0.001). Factorsassociated with high rate of HCV infection were those related to intravenous drug use and tattooinginside the prison. Despite of strict preventive and control measures imposed by the prison, suchbehaviors still proliferated. Provision of withdrawal clinics, followed by rehabilitation programs,may be more appropriate. Conventional harm reduction measures may not be effective since suchmeasures are against the rules of the prison.Key words: HCV infection, prevalence, incidence, Thai inmates, abused drug injection