Estonia at the threshold of the fourth decade of the AIDS era in Europe.

This article describes the trends of HIV/AIDS and related conditions in Estonia during the past decade (2000-2009), with special focus on the potential for epidemic transition. Key transmission determinants and major risk groups are examined and problems and barriers to fighting HIV/AIDS with possible applications in prevention and control are described. Estonian routine data sources and published literature were reviewed, supplemented with information from personal communication with physicians and public health specialists. For comparative European data, international HIV/AIDS and drug addiction surveillance documents, administrative data, and published literature were reviewed. In Eastern Europe (including Estonia) the predominant HIV transmission mode is injection drug use (IDU), closely followed by heterosexual transmission, an increasing risk factor for new cases. Although the contribution of cases acquired by sexual contact with high-risk partners such as IDUs is not known, characteristics of the sexual networks of IDUs may be important in determining the evolution of the HIV/AIDS epidemics in the region. In Estonia, despite major gaps in available data, the HIV/AIDS epidemic is still presumably confined to IDUs (and probably, to their sexual partners). In Eastern Europe, young women in IDU-non-IDU partnerships engaging in unprotected sex potentially serve as a bridge to the general population, yet knowledge of and research into the population characteristics and potential magnitude of bridging are limited. In Estonia, as in other Eastern European countries, HIV prevention and harm reduction initiatives should be tailored not only to the predominantly male HIV-positive IDU population, but also to their noninfected non-IDU female sexual partners.