1. Multiple HIV-1 introductions into the Swedish intravenous drug user population.
- Author
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Skar H, Sylvan S, Hansson HB, Gustavsson O, Boman H, Albert J, and Leitner T
- Subjects
- Europe epidemiology, Female, HIV Infections transmission, HIV-1 classification, Humans, Male, Molecular Epidemiology, Phylogeny, Reproducibility of Results, Sweden epidemiology, Time Factors, HIV Infections epidemiology, HIV Infections virology, HIV-1 genetics, HIV-1 isolation & purification, Substance Abuse, Intravenous epidemiology, Substance Abuse, Intravenous virology
- Abstract
In 2001, an increase of HIV-1 diagnoses among intravenous drug users (IVDU) was reported in Sweden. In nearby countries, Finland, Russia and the Baltic states, recent outbreaks had been described. Since there was a concern that these outbreaks would carry over to Sweden a study was initiated to determine the factors leading to the Swedish increase of HIV-1 diagnosed IVDUs. HIV-1 env V3 sequences were obtained from 97 patients enrolled in ongoing epidemiological studies encompassing the years 1987--2004 with a focus on 2001--2002. The sequences were used for maximum likelihood and Bayesian inference of the molecular epidemiology. Among the virus spreading in 2001--2002, we found that four different subtypes/CRFs were present in the Swedish IVDU population (A, B, CRF01_AE and CRF06_cpx). Subtype B constituted 85% of the infections, established by 12 independent introductions into the IVDU population. The worrisome increase in 2001 was mainly not a result of import of the outbreaks in nearby countries, but rather a higher detection rate of secondary cases due to efficient epidemiological tracing of the generally slow spread of established forms of subtype B in the IVDU community. However, a few of the non-subtype B cases were linked to the outbreaks in Finland, Estonia and Latvia. Because HIV-1 outbreaks can easily be exported from one country to another amongst IVDUs, this prompts continued surveillance in the Baltic Sea Region.
- Published
- 2008
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