Background: The aim of the study was to measure risk of HIV and HCV infection among injecting drug users (IDUs) through force of infection (FOI) models in three cities of the Russian Federation and assess the value of behavioural data and FOI in predicting risk of infection as a method of second-generation surveillance. Methods: FOI models were fitted to prevalence data collected through an anonymous, cross-sectional community-recruited survey of IDUs with oral fluid sample collection for antibodies to HIV and HCV. Risk of infection was estimated from FOI estimates obtained by fitting a model to prevalence data by length of injecting career for each city and then overall. Risk behaviours were examined by injecting career length. Results: A total of 1473 IDUs were recruited. Prevalence of HIV was 8.1 (95 CI 6.79.6) and HCV 63.4 (95 CI 60.965.9). A higher FOI in new initiates to injecting (injecting career length <1 year) was found for both HIV and HCV compared with experienced IDUs (injecting career length <5 years). Increased risk of infection was not corroborated by injecting risk behaviours among new initiates into injecting (n 38). Only 5.7 (n 2) reported receptive sharing in the last 4 weeks, 57.9 (n 22) sharing any injecting paraphernalia, 2.6 (n 1) frontloading and 8.5 (n 3) ever injecting with used needles/syringes. However, 29 of new initiates reported exchanging sex in the last 4 weeks (29) compared with 11 long term IDUs. Conclusions: FOI models can play an important role in surveillance of HIV but caution is needed in the interpretation of behavioural data for predicting current or future risk of HIV.
Bibliographical noteFunding Information:
We are grateful for the support of the UK Department for International Development who supported this study through programme grants, and to the UK Department of Health who provide core funding to the Centre for Research on Drugs and Health Behaviour. We thank the study participants, and the following: Sergei Belikh; Irina Berezhnova; Dimitry Blagov; Natalia Bobrova; Elvira Demyanyenko; Alexander Fillipov; Nadezhda Gorshkhova; Elena Kudravtseva; Peter Madden; Olga Mikhailova; Adrian Renton; Anya Sarang; Nelly Savelevna; Lenar Sultanov; Grigoryev Svyatoslav; Mikhail Tichonov; Venyamin Volnov; Konstantin Vyshinsky; Martin Wall. This article is dedicated to the memories of our colleagues and friends Andrei Rylkov and Nadezhda Zabotina.
- Force of infection
- Risk of infection