After the collapse of the Soviet Union, Estonia has experienced major political, economic and social changes associated with declines in health and life expectancy as well as growth in informal economies, including drugs and the sex trade [1,2]. Estimates indicate that 20 000 individuals, or 2.6% of the population aged 15–64 years, are injecting drugs . The spread of HIV in Estonia is characterized by rapid transmission associated with drug injecting, but there is little reliable evidence estimating the prevalence of antibodies to HIV among injecting drug users (IDU).
From May to June 2005, we conducted an unlinked anonymous cross-sectional survey of IDU recruited from non-treatment settings in Tallinn and Kohtla-Jarve using ‘respondent-driven sampling’ [4–6]. The inclusion criteria were injection in the past 4 weeks and giving a dried blood specimen for HIV testing. Interviews took place at fixed needle exchange sites administered by trained field workers (nurses or employees from the needle exchange programmes). Ethical approval was obtained from the Riverside Research Ethics Committee, UK, and from the Ethics Review Board of the University of Tartu, Estonia.
Dried blood spot specimens were collected using single-use disposable lancets and neonatal Guthrie cards to detect antibodies to HIV (anti-HIV) [7,8]. Specimens were screened at the UK Health Protection Agency using anti-HIV IgG antibody-capture enzyme-linked immunosorbent assay (GACELISA), reactive specimens were confirmed using anti-HIV IgG antibody-capture particle adherence test (GACPAT) immunoassay, with confirmatory testing conducted on discordant results using the HIV blot 2.2 Western blot assay (Abbott Murex, Abbott Park, Illinois, USA) . Behavioural data were collected through a structured questionnaire.
Risk behaviours and characteristics were compared between the two cities. Pearson's χ2 tests were used for categorical variables and t tests with equal variance for continuous variables. Associations between antibodies to HIV (the outcome of interest) and covariables were explored univariably and by multiple logistic regression for the Tallinn sample only. Intracluster correlation coefficients were calculated to measure the degree to which observations from individuals recruited by the same individual were correlated, and a random effects model was used to adjust for any correlation. Multivariable analysis followed a conceptual framework approach described previously [10,11]. Analyses were conducted using Stata 7 (Stata Corp, College Station, Texas, USA).
A total of 350 drug injectors were recruited in Tallinn, and 100 in Kohtla-Jarve. The prevalence of HIV was 54% [95% confidence interval (CI) 49.0–59.5%] in Tallinn and 90% (95% CI 83.8–95.9%) in Kohtla Jarve (P < 0.001). Over half of the sample in both cities was under 25 years of age, of Russian nationality (P = 0.2), and over 80% were men (data not shown). A higher proportion of participants in Kohtla-Jarve (77%) reported not having a regular source of income compared with Tallinn (52%, P < 0.001). Injecting drug use and risk behaviour characteristics varied by city. Greater proportions of IDU in Tallinn reported shorter injection careers, whereas fewer reported injecting daily (38 versus 75%, P < 0.001). The majority (90%) of injectors in Kohtla-Jarve mainly injected mak, a liquid derivative of opium poppy straw, whereas the majority (74%) in Tallinn favoured ‘china white’, an illicitly manufactured synthetic opioid made from fentanyl (P < 0.001) . A higher proportion of IDU in Tallinn reported injecting with a used needle/syringe in the past 4 weeks (28 versus 18%, P = 0.06) and injecting with a used needle/syringe of their sex partner in the past 12 months (29 versus 17%, P = 0.02). In both cities approximately 60% reported having two or more sex partners in the past 12 months, approximately 60% reported ever having been in prison, and 80% reported ever having used the needle/syringe exchange. Proportionally more participants in Kohtla-Jarve than Tallinn reported being registered as an IDU at a drug treatment centre (65 versus 40%, P < 0.001).
In the univariable analysis increased odds of anti-HIV positivity were associated with non-Estonian ethnicity [odds ratio (OR) 2.1; 95% CI 1.1–4.0], duration of injecting, daily injection (OR 1.8; 95% CI 1.2–2.9), and mainly injecting china white (OR 4.6; 95% CI 2.6–8.2; Table 1). Anti-HIV positivity was also associated with using needles/syringes of sex partners in the past 12 months (OR 2.7; 95% CI 1.6–4.5%), a history of prison (OR 1.6; 95% CI 1.0–2.5), being registered as an IDU at a drug treatment centre (OR 2.4; 95% CI 1.5–3.8) and ever having attended a needle/syringe exchange (OR 2.2; 95% CI 1.2–3.8).
After adjustment, only three variables remained significantly associated with increased odds of anti-HIV positivity. IDU who mainly injected china white had three times the odds of being anti-HIV positive than those who injected amphetamines (OR 3.3; 95% CI 1.7–6.4); those injecting with used needles/syringes of their sex partners in the past 12 months had twice the odds (OR 2.4; 95% CI 1.4–4.3); and those who were registered as an IDU at a drug treatment service had 1.8 times the odds of being anti-HIV positive (95% CI 1.1–3.0).
It is not since the explosive outbreaks of HIV among IDU in south east Asia in the mid-1980s that such high city estimates of prevalence have been reported [2,13]. We recommend the immediate scale up of HIV prevention programmes targeting IDU and their sexual partners. There are approximately 20 needle/syringe exchange programmes in Estonia reaching approximately 30% of IDU, with fewer proportions of IDU receiving methadone maintenance or free access to HAART .
Our findings associate an increased risk of HIV in Tallinn with sharing injecting equipment with a sex partner. We looked at injecting with a sex partner specifically because previous findings suggest that IDU are more likely to share used injecting equipment with a sex partner and this may go unreported as syringe sharing but be rationalized as ‘safer’ than sharing with less intimate others [15–18]. In the context of a high background HIV prevalence, with over half the sample reporting two or more sex partners in the same time frame, this is an important finding for the targeting of HIV prevention.
The social and economic changes associated with political transition influenced Estonians and Russians very differently. Over 25% of Estonia's population is of Russian origin, but almost a third of ethnic Russians do not have citizenship rights, which limits their ability to travel, employment opportunity as well as community or political participation [19,20]. Our findings show a markedly higher prevalence of HIV among IDU in Kohtla Jarve, which has a larger Russian population. Although the interplay of such social structural factors in the creation of an environment of risk and vulnerability is difficult to gauge, evidence of city differences in injecting risk behaviours and environmental factors points to the importance of delineating how social and structural factors may mediate HIV transmission risk differently in different contexts [10,21].
The authors would like to express gratitude to Roman Družinin, Galina Ermel, Evegenia Karasjeva, Pjotr Kutuzov, Jaana Laanemann, Aleksander Laanemann, Anya Sarang, Igor Sobolev Aire, Trummal, Margus Zahharov and all the participants of the study.
Sponsorship: The authors are grateful to the Global Fund to Fight AIDS, Tuberculosis and Malaria who funded this study through the National Institute for Health Development in Estonia.
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