Abstract
BACKGROUND OBJECTIVES: The seroprevalence of the hepatitis C virus (HCV) in general population is higher than that of human immunodeficiency virus (HIV) in India. People who inject drugs (PWIDs) constitute a high-risk group for all blood-borne infections. Multiple behavioural surveillance surveys have provided a rich typology of HIV-infected PWIDs, but this information is missing for HCV infection. We describe awareness, transmission risk factors and the treatment continuum for HCV infection among PWID. We also report spatial clustering of HCV infection in PWIDs residing in Bengaluru. METHODS: Information from clinical records was collected and telephonic interviews of retrospectively identified PWIDs who received treatment at a tertiary-level addiction treatment facility between 2016 and 2021 were conducted. RESULTS: We identified 391 PWIDs; 220 (56.26%) received an anti-HCV antibody test (4 th Generation HCV-Tridot). Individuals reporting unsafe injection practices were more often tested than those who did not ( χ2 =44.9, df=1, P <0.01). Almost half of the tested and more than a quarter of the whole sample (109/220, 49.9%; 109/391, 27.9%) were seropositive for HCV infection. The projected seropositivity in this group was between 27.9 per cent (best case scenario, all untested assumed negative) and 71.6 per cent (worst case scenario, all untested assumed positive). Only a minority of participants interviewed were aware of HCV (27/183, 14.7%). HCV infection and its associated risk behaviour (PWID) were clustered in certain localities (Diggle and Chetwynd Test; P =0.001) in Bengaluru in the southern district of Karnataka. INTERPRETATION CONCLUSIONS: Undetected HCV infection is common in PWIDs; awareness and treatment uptake is poor in this group. Spatial clustering of infections in a district shows transmission in close networks and provides opportunities for targeted interventions.