Avian influenza viruses found in Finnish wild birds are not pathogenic


<div>Evira examined in 2003-2007 a total of 2503 wild birds in Finland for influenza A viruses. The results of these avian influenza surveillance show that avian influenza viruses of different subtypes circulate in both wild ducks and seagulls, but they are not pathogenic in type.</div>

Most of the examined birds, or about 80%, were waterfowl or waders. Influenza A virus was observed in 32 samples. These samples contained six different subtypes of the influenza A virus. One of the subtypes was H5N2, but it was not of the pathogenic strain. The viruses were found in wild ducks and seagulls. All the viruses found in wild ducks were in birds hunted in the autumn. The seagulls that carried the viruses had been sent to Evira for a post mortem investigation.

Evira has received samples for avian influenza surveillance from various parts of the country both from bird ringers and since 2006 also from hunters. Some of the wild birds on which Evira's Oulu Research Unit of Fish and Game Health has performed a post mortem have also been included in the surveillance. 

Influenza A viruses comprise a group of viruses that is particularly characteristic of waterfowl. The majority of the subtypes of influenza A virus do not cause any notable symptoms in the birds. However, two of the subtypes (H5 and H7) also include viruses (e.g. H5N1), which can cause severe avian influenza epidemics in poultry.

Influenza A viruses have been isolated from wild birds on all continents except the Antarctic. According to current views the genetic material of all influenza A viruses is primarily carried by waterfowl, which maintain the strains in the wild. Influenza A viruses are multiplied in the intestines of the bird and excreted in large amounts in the faeces. In water they spread from the faeces to the other birds. 

For more information, please contat
Christine Ek-Kommonen, Veterinarian, Head of Section, Veterinary Virology Research Unit, Evira, tel. +358 (0) 20 77 24583, GSM +358 (0) 50 5143926


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