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Orthomyxo-, paramyxo- and flavivirus infections in wild waterfowl in Finland

Erika Lindh1*, Anita Huovilainen2, Osmo Rätti3, Christine Ek-Kommonen2, Tarja Sironen1, Eili Huhtamo1, Hannu Pöysä5, Antti Vaheri16 and Olli Vapalahti146

Author Affiliations

1 Department of Virology, Haartman Institute, Faculty of Medicine, P.O. Box 21, FI-00014 University of Helsinki, Finland

2 Finnish Food Safety Authority Evira, Department of Animal Diseases and Food Safety Research, Virology Unit, Mustialankatu 3, FI-00790 Helsinki, Finland

3 Arctic Centre, University of Lapland, P.O. Box 122, FI-96101 Rovaniemi, Finland

4 Division of Microbiology and Epidemiology, Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, P.O. Box 66, FI-00014 University of Helsinki, Finland

5 Finnish Game and Fisheries Research Institute, Joensuu Game and Fisheries Research, Yliopistonkatu 6, FI-80100 Joensuu, Finland

6 Department of Virology, HUSLAB, Hospital District of Helsinki and Uusimaa, P.O. Box 400, FI-00029 HUS, Helsinki, Finland

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Virology Journal 2008, 5:35  doi:10.1186/1743-422X-5-35

Published: 28 February 2008

Abstract

Background

Screening wild birds for viral pathogens has become increasingly important. We tested a screening approach based on blood and cloacal and tracheal swabs collected by hunters to study the prevalence of influenza A, paramyxo-, flavi-, and alphaviruses in Finnish wild waterfowl, which has been previously unknown. We studied 310 blood samples and 115 mixed tracheal and cloacal swabs collected from hunted waterfowl in 2006. Samples were screened by RT-PCR and serologically by hemagglutination inhibition (HI) test or enzyme-linked immunosorbent assay (ELISA) for influenza A (FLUAV), type 1 avian paramyxo-(APMV-1), Sindbis (SINV), West Nile (WNV) and tick-borne encephalitis (TBEV) virus infections.

Results

FLUAV RNA was found in 13 tracheal/cloacal swabs and seven strains were isolated. Five blood samples were antibody positive. Six APMV-1 RNA-positive samples were found from which four strains were isolated, while two blood samples were antibody positive. None of the birds were positive for flavivirus RNA but three birds had flavivirus antibodies by HI test. No antibodies to SINV were detected.

Conclusion

We conclude that circulation of both influenza A virus and avian paramyxovirus-1 in Finnish wild waterfowl was documented. The FLUAV and APMV-1 prevalences in wild waterfowl were 11.3% and 5.2% respectively, by this study. The subtype H3N8 was the only detected FLUAV subtype while APMV-1 strains clustered into two distinct lineages. Notably, antibodies to a likely mosquito-borne flavivirus were detected in three samples. The screening approach based on hunted waterfowl seemed reliable for monitoring FLUAV and APMV by RT-PCR from cloacal or tracheal samples, but antibody testing in this format seemed to be of low sensitivity.