“This situation has never been encountered in France due to its scale and the period” indicates the latest epidemiological bulletin weekly from the Esa epidemiological surveillance platform published on June 21.
Indeed, since May, more and more seabirds have been found dead on the coasts of the northern littoral of France. This phenomenon is rather unusual, as highly pathogenic avian influenza (AI) viruses strike waterfowl and raptors more.
The most important contributors are usually Anatidae
© ESA Platform
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As of June 17, these mortalities have been reported in four communes in the Somme, ten communes in Pas-de-Calais, three in Nord Sur, three in Seine-Maritime, and one commune in Aisne, Calvados and Manche. The reports show a chronological evolution over more than 500 km, from the Belgian border to Brittany. Grouped mortalities were observed mainly on gulls (gulls, terns, gulls), but not exclusively.
The Somme was particularly affected (Marquenterre park) including a northern gannet (Morus bassanus) the largest seabird in Europe.
In the Netherlands, a gannet was also found dead and carrying the H5N1 virus. In Scotland several thousand dead lunatics have also been reported.
In France, the only colony of northern gannets is on the north coast of Brittany, with 15 to 20,000 pairs concentrated on Rouzic Island (Sept Iles nature reserve) representing 4% of the world population.
Endemic presence of AI viruses
The persistence of HPAI H5N1 virus circulation in wild bird populations during the off-season (between descending and ascending migrations) is of concern, especially since some species are partial migrants or include colonies in the process of breeding and rearing juveniles.
“Environmental contamination remains high in regions where wild bird mortalities are observed” further emphasizes the Esa platform. “The risk of introduction of the virus into poultry farms can occur through the decantation of wild bird populations, which is always possible even outside periods of migratory movements. »
Seabird mortalities are observed all over the world. In June, Russia declared more than 2,200 dead birds in the Caspian Sea (mainly terns). In May, Canada reported deaths never seen in the Magdalen Islands, including hundreds of gannets, found emaciated. Ornithologists wonder if these birds were weakened by the AI viruses preventing them from fishing or if their weight loss resulted in an increased susceptibility to the AI viruses.
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