An outbreak of the circulating recombinant form AECM240 HIV-1 in the Finnish injection drug user population

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Injecting drug use accounts for the largest and increasing proportion of AIDS cases in Europe. In several western European countries the incidence of HIV among injection drug users (IDU) peaked in the middle of the 1980s and is now decreasing, whereas in the area of the former Soviet Union the number of HIV infections among IDU has dramatically increased since 1995 [1–4]. In Finland the first HIV infection associated with injection drug use was diagnosed as late as 1986. At the end of 1997, only 3% (n = 27) of all HIV cases were associated with injection drug use, and almost all of them were acquired in some western European country outside Finland. However, at the end of the summer of 1998, the number of newly diagnosed HIV infections started to increase. In contrast to previous cases, new cases appeared to have been domestically acquired. In 1998 19 and in 1999 82 new injection drug use-associated infections were diagnosed, representing a significant increase in the incidence of injecting drug use-associated HIV-1 and suggesting epidemic spread [5]. Earlier molecular studies showed that the HIV epidemic in Finland was heterogeneous: subtype B dominated among homo/bisexual men, whereas infections associated with heterosexual contact were caused by multiple genetic subtypes [6]. Both in the USA and western Europe, HIV strains among IDU previously exclusively belonged to subtype B [7–10], whereas in the area of the former Soviet Union subtype A predominated among IDU [11–15]. Because of the geographical proximity of these regions, it might have been expected that either the B or A subtype would have caused the recent IDU HIV-1 epidemic in Finland. Blood samples were collected from 21 Finnish IDU found to be HIV positive during the first 12 months of the outbreak (March 1998–February 1999). In addition, stored samples (n = 8) from IDU infected before the outbreak were analysed. All pre-1998 samples were found to represent subtype B using the NCp7 or C2-V3 genome region. All HIV-1 sequences, except one, derived from the newly infected IDU formed a tight cluster with low interpatient variation (NCp7: mean 0.3%, range 0–2.3%; C2-V3: mean 0.1%, range 0–0.9%), suggesting that they represented an early stage of the epidemic, which probably started from a single source. One IDU diagnosed HIV positive in 1999 did not belong to the cluster and was infected with a subtype B virus. Surprisingly, all other sequences were found to belong to the circulating recombinant form, AECM240 (CRF01_AE), commonly found in southeast Asia [16–20]. This is the first reported outbreak caused by CRF01_AE in Europe and it emphasizes the unpredictability of HIV epidemics (see Fig. 1).Fig. 1.: Phylogenetic threes based on the NCp7 region in the gag gene and the C2-V3 region in the env gene. Genetic typing of viruses was carried out from total DNA isolated from 1.5 ml frozen blood using the QIAamp Blood midi kit (Qiagen Hilden, Germany). The NCp7 and C2-V3 regions were amplified using nested polymerase chain reaction and directly sequenced using automated sequencer ABI377 (PE Biosystems, Foster City, CA, USA). Bootstrap values (100 replicates, Clustal) are shown at nodes. Brackets at the right indicate the subtypes. Finnish injection drug user (IDU) sequences are shown in bold. Sequences from IDU diagnosed HIV positive before the outbreak are marked with asterisks.Ten newly diagnosed IDU contacting the Aurora Hospital were interviewed. All individuals were living in temporary shelters. One was on an incapacity pension as a result of mental illness, two were receiving sickness benefits and seven were receiving unemployment and social security benefits. The interviews strongly indicated that the outbreak started in a subpopulation of IDU characterized by chaotic lifestyles, social exclusion and severe problems of unemployment, homelessness and crime. Also, unlinked-anonymous saliva samples from 135 individuals attending a needle exchange programme in Helsinki in September 1998 were collected to estimate the seroprevalence of HIV and hepatitis C virus (HCV) among IDU. Three per cent (n = 4) of the saliva samples collected were HIV antibody positive and 63% (n = 85) were HCV positive. All four anti-HIV-positive samples were also HCV positive. The magnitude of the epidemic cannot be estimated at the moment, but new cases are still reported. The preliminary results show that the newly revealed cases still carry the same virus type as at the start of the epidemic. Most previous studies [21] demonstrated that cities with properly executed needle exchange programmes could reduce the incidence of HIV among IDU. In Helsinki, the first such programme was established in 1997, before the current outbreak. However, it was established as a pilot with very limited resources, only operating two nights a week and only in one location. The poor coverage probably limited the effectiveness of the programme. Simultaneously, many pharmacies in the Helsinki area, which had previously legally sold needles and syringes to IDU, stopped doing so. This situation, coupled with the increased use of injectable drugs, probably created circumstances favourable for an outbreak [22]. In the current situation, swift measures will be needed in Finland to limit the extent of the epidemic. As well as advice and counselling on drug abstinence and detoxification and rehabilitation programmes, an alternative intervention strategy recognizes that not all users wish to come off drugs. Kirsi Liitsolaa Matti Ristolab Pekka Holmströma Mika Salminena Henrikki Brummer-Korvenkontioa Susan Simolab Jukka Sunic Pauli Leinikkia