Theme: Epidemiology & Public Health Research Year: 2015
Introduction:
Hepatitis C virus (HCV) is predominantly transmitted between people who inject drugs (PWID) with high global prevalence. Incarceration is common among PWID, and is an independent risk factor for HCV acquisition. However, HCV transmission dynamics in incarcerated populations have not yet been previously explored. We integrated viral sequences with risk behaviour and spatio-temporal data to analyse transmission clusters and better understand HCV transmission in an Australian prison setting.
Methods:
Longitudinal HCV laboratory data, risk behaviour, and spatio-temporal information were collected from 498 subjects enrolled in HITS-p – a prospective cohort of high-risk HCV-uninfected prisoners recruited and followed in 37 NSW prisons from 2005 to 2012. Phylogenetic analysis was performed on viral sequences (E1-HVR1) of 79 incident cases. An empirically-defined, conservative patristic distance threshold was used to detect transmission clusters, which were then validated using estimated dates of infection, risk behaviour, and data regarding the specific custodial locations and period of incarceration.
Results:
Three clusters of recent HCV transmission were detected consisting of four likely in-custody transmission events identified involving source-recipient pairs co-located in the same prison at the same time. Three of the events were associated with drug injecting and equipment sharing behaviour.
Conclusion:
Despite a very large reservoir of prisoners with chronic HCV, recent transmission events were identified in the prison setting. Ongoing HCV transmission among high-risk prisoners advocates for the expansion of intervention programs to reduce transmission in prisons.