Epidemiology of HIV in Estonia

The aim of this study was to report on the epidemiology of HIV infection in Estonia and to molecularly characterize Estonian HIV-1 variants. Epidemiol ogical data were obtained from the Estonian National HIV/AIDS Database. In 1995-1996 blood samples were collected from 54 of the 65 HIV-infected indiv iduals that had been diagnosed at that time, The V3 domain of the env gene was directly sequenced from peripheral blood mononuclear cells of 49 of the se 54 individuals and the sequences used for phylogenetic analyses. At the end of 1999 Estonia reported 96 diagnosed HIV cases; 46 (48%) were homosexu al or bisexual men and 31 (32%) were presumed to have been infected heteros exually. Importantly, only four individuals were likely to have become infe cted through intravenous drug use. Forty-three individuals (45%) were presu med to have been infected outside of Estonia, whereas 38 (40%) were likely to have become infected in Estonia, As expected, a majority of the investig ated individuals (80%) were found to carry subtype B virus. Infections with subtypes A, C, D, G, and CRF02_AG were also documented. The dominance of s ubtype B was restricted to homosexual and bisexual men. Thus, subtype B inf ections were documented in 33 of 34 (97%) homosexual and bisexual men, hut only 6 of 15 (40%) individuals with other probable routes of infection. Thi rty of the 39 subtype B sequences were joined in a tight sequence cluster t hat also included sequences from neighboring Russia and Lithuania. This pat tern suggests a local spread of HIV-1 among homosexual and bisexual men wit hin the region. The results from the phylogenetic analyses agreed well with other epidemiological information. In conclusion, Estonia remains a countr y with a low prevalence of HIV infection. A majority of the identified case s are homosexual or bisexual men, whereas HIV infection among intravenous d rug users is rare. A large proportion of the homosexual and bisexual men ca rried closely related subtype B variants. The sequences have been deposited in GenBank under accession numbers AF286538-AF286586.