Molecular Characterization of HCV in a Swedish County Over 8 Years (2002–2009) Reveals Distinct Transmission Patterns

Background

Hepatitis C virus (HCV) is a major public health concern and data on its molecular epidemiology in Sweden is scarce. We carried out an 8-year population-based study of newly diagnosed HCV cases in one of Sweden's centrally situated counties, Södermanland (D-county). The aim was to characterize the HCV strains circulating, analyze their genetic relatedness to detect networks, and in combination with demographic data learn more about transmission.

Methods

Molecular analyses of serum samples from 91% (N=557) of all newly notified cases in D-county, 2002–2009, were performed. Phylogenetic analysis (NS5B gene, 300 bp) was linked to demographic data from the national surveillance database, SmiNet, to characterize D-county transmission clusters. The linear-by-linear association test (LBL) was used to analyze trends over time.

Results

The most prevalent subtypes were 1a (38%) and 3a (34%). Subtype 1a was most prevalent among cases transmitted via sexual contact, via contaminated blood, or blood products, while subtype 3a was most prevalent among people who inject drugs (PWIDs). Phylogenetic analysis revealed that the subtype 3a sequences formed more and larger transmission clusters (50% of the sequences clustered), while the 1a sequences formed smaller clusters (19% of the sequences clustered), possibly suggesting different epidemics.

Conclusion

We found different transmission patterns in D-county which may, from a public health perspective, have implications for how to control virus infections by targeted interventions.

Below:  Genotype distribution found among the risk factors associated with HCV in patients first notified during 2002–2009. *Unknown=unknown or no information reported. Other=care-related transmission as patient/staff, mother to child/pregnancy, tattoo/piercing, other.

Full article at:   http://goo.gl/n6FJXO

By:  Josefine Ederth, PhD,1,* Camilla Jern, MD,2 Helené Norder, PhD, Associate Professor,3 Lars Magnius, MD, Professor,3Erik Alm, PhD,1 Björg Kleverman Rognsvåg, BSc,4 Carl-Gustaf Sundin, MD, County Medical Officer,5 Mia Brytting, PhD, Associate Professor,1 Joakim Esbjörnsson, PhD,6,7,† and Mattias Mild, PhD1,†

¹Department of Microbiology, Public Health Agency of Sweden, Solna, Sweden

²Stockholm South General Hospital, Stockholm, Sweden

³Department of Infectious Medicine, Institute of Biomedicine at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden

⁴Unilabs AB, Mälarsjukhuset Hospital, Eskilstuna, Sweden

⁵Department of Communicable Disease Control, Södermanland County, Sweden

⁶Department of Microbiology Tumor and Cell Biology, Karolinska Institute, Stockholm, Sweden

⁷Nuffield Department Medicine, University of Oxford, Oxford, United Kingdom

*Correspondence to: Josefine Ederth, Department of Microbiology, Public Health Agency of Sweden, Solna, Sweden, Email:es.netehgidnymoslahklof@htrede.enifesoj

Responsible Editor: Tanja Strand, Uppsala University, Sweden.

^†Joakim Esbjörnsson and Mattias Mild have contributed equally to this study.

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