This is the first assessment of correlation between high-risk sexual and injecting behaviours and prevalence of blood-borne infections among Estonian IDUs. This seminal study is particularly relevant given the recent expansion of HIV in this region.11
As has been described in other reports on IDUs from Estonia,10,12
the vast majority of IDUs recruited in Tallinn were non-ethnic Estonians (mostly ethnic Russians). Elevated rates of high-risk behaviour and greater HIV infection among ethnic minority drug users have been noted in multiple settings.13–15
In Estonia, the non-Estonian ethnic minority (95% Russian speaking) comprises 30% of the total population, and the majority (83%) of the Russian speaking populations live in the Northeast or in the capital area of the county.16
The HIV seroprevalence in our sample was 25.0% among ethnic Estonians, 58.8% among ethnic Russians, and 56.3% among other ethnic groups (all Russian speaking). Non-ethnic Estonian ancestry and heroin use were the only statistically significant factors related to HIV seropositivity. Notably, none of the following risk factors appeared significant: age, gender, length of injection drug or alcohol abuse, injection equipment sharing and sexual high-risk behaviours.
Employment for the Russian-speaking population was largely concentrated in segments of the economy that collapsed after the restoration of Estonia’s independence, deepening the problem of unemployment17
and social marginalization. Geographical proximity of the Estonian North-East county (the highest HIV/IDU levels in Estonia) to St Petersburg (Russian Federation) – an area with high rates of HIV/IDU18
– could be an important confounding factor for the observed correlation of HIV/IDU with ethnic origin. Nevertheless, ethnically discrepant patterns have emerged in drugs used (cocaine and amphetamines are preferred to heroin and opiates by ethnic Estonians), modes of drug use (preferably non-injecting drug use by ethnic Estonians) and initiation of drug use (non-ethnic Estonians are more likely to start their drug using career with injecting).19
Additional sociological studies to investigate the association between ethnicity and higher disease prevalence are clearly needed.
Our brief descriptive study does allow us to highlight the temporal hierarchy in substance abuse patterns among Estonian IDUs. Although our study revealed a sequential pattern that begins with tobacco and is followed by marijuana, home-made opiate injection and heroin injection in that order, these data neither support nor refute a gateway drug theory. Since all participants were IDUs, there is no causal evidence that initiation of any one or any particular series of psychoactive or addictive substances led to subsequent injection drug use.
Further study is needed to investigate the relationships among injection drug use, alcohol use and unsafe sex. Over a half of the population had a CAGE score indicating alcohol-related problems. Problem drinking is associated with an increased risk of STDs across a wide variety of populations.20
Our observation of the high level of alcohol abuse suggests that identification and treatment of alcohol abuse may be an important and desirable component of HIV prevention in Estonia. Further studies are needed to ascertain the precise relationships between these variables.
High rates of bacterial sexually transmitted infections among disenfranchised population groups in Moscow were recently reported by Shakarishvili et al
While the overall HIV infection prevalence was below 3% among those surveyed, the authors noted that the high prevalence of STDs in these groups may foreshadow a dramatic increase in HIV infections in the Russian Federation.21
In the current study, most participants reported being sexually active, with over one-fourth having more than five sexual partners within past 12 months, and one-third of the men paying for sex. All these factors are associated with high HIV prevalence and frequent symptomatic STDs. The finding that more than three-quarters of current IDUs report non-IDU sexual partners underscores the urgent need for sex risk reduction and prevention research in the IDU community. Further understanding the high-risk networks (sexual, drug using) of IDUs and between IDUs and the general population will be important for developing targeted HIV transmission prevention activities.
There are worrisome signs of ongoing marginalization of the young IDUs, as indicated by the high proportion of young persons neither working nor studying (41.4%) and a decreasing proportion of persons covered by state health insurance (57% in 2003, 39% in 2004). As has been suggested by Wallace, marginalization leads to the changes in lives of individuals and families, and also in the social construction of a neighbourhood. Youth behaviours such as doing well in school, getting a regular job, avoiding substance abuse and maintaining stable relationships become more difficult as the neighbourhood structures that value such attainments dissolve. Negative acts such as violent behaviour, multiple sexual conquests and drug taking are messages that tend to be more easily disseminated in a dissolving community.22,23
Last but not least, we observed a very high prevalence of HIV and other blood-borne infections among our respondents. Similarly, high HIV seroprevalence has been reported from other cities/regions of former Soviet Union.18,24
The high infection levels increase the urgency of secondary prevention. The extremely frequent co-infections among the HIV-infected IDUs will complicate the treatment for HIV, if and when it becomes available. Information on HIV prevalence within the IDU population in the other two Baltic countries (Lithuania and Latvia) is scarce, and warrants further exploration. According to the surveillance data, 71% of HIV cases reported from Latvia and 80% from Lithuania can be attributable to IDU.25
It is worth reviewing the limitations of the study. The nature of a cross-sectional study permits only prevalence measures and does not allow for incidence measures. Further, cross-sectional studies do not permit us to establish causal relationships or directions of causality. Another limitation of the study design is the use of a convenience sample instead of probability or adaptive sampling. However, convenience sampling is particularly well suited to studying populations without a sampling frame and which are hard to target, such as IDUs. We realize that the characteristics of IDUs can differ from site to site, and we do not suggest that our findings are entirely generalizable to other Estonian IDUs or even those IDUs visiting other Estonian SEPs.
Another limitation of the study is lack of confirmation for HIV enzyme immunoassay (EIA) testing. We used one test system (HIV-1/HIV-2 III Plus from Abbott Laboratories) to detect HIV-1/HIV-2 antibodies for study purposes. Given the high number of positive HIV test results and high cost, it was not feasible to perform confirmatory testing. However, the excellent characteristics of the test system used – both sensitivity and specificity close to 100%26
– and the high prevalence of HIV, suggest that the percentage of false-positive or -negative results were likely to be minimal and had no impact on the results of the study.
Despite these limitations, several inferences can be made. First, the problem of higher rates of HIV infection and injection drug use among racial/ethnic minorities may be a general pattern in many areas. Whether such higher rates can be reduced must be considered a critical question in the international epidemiology of HIV among IDUs. Second, as a summary of the current epidemic outlook in Estonia, our work demonstrates the intersection of several epidemics, including drug use, HIV and viral hepatitis. These epidemics are further characterized by high infection rates and the exceptionally young age of those affected. Third, the contribution of heavy alcohol use to amplify the course of epidemics could be substantial. Fourth, complicated questions for international prevention efforts are raised by the degree to which these young people frequently travel both to former Soviet Union states and to Western Europe (especially Scandinavian countries). The appropriate responses to these issues should be focused on scientifically validated, evidence-based approaches to secondary prevention among the HIV infected, especially given uncertainties surrounding the availability, cost and sustainability of antiretroviral and substance abuse treatments. This descriptive study of Estonian IDUs portends an enormous burden on health systems and economic productivity.