Wetenschap - 27 november 2014

Bird flu flown in from Asia

The bird flu virus affecting poultry farms in the Dutch villages of Hekendorp, Ter Aar and Kamperveen is highly likely to have been brought to Europe by migrating birds.

This conclusion comes from an analysis by the Central Veterinary Institute (CVI). The bird flu virus type H5N8 was confirmed on a German turkey farm on 6 November. Genetic research established that it was almost identical to the viruses which were found this year on poultry farms in South Korea, China and Japan. What is more, a wild duck in the same region of Germany was found to have been infected with H5N8 last week. The CVI has not found any direct evidence of a relation between migrating birds and an outbreak of bird flu, but migrating birds are the most likely source of the virus, says CVI researcher Ruth Bouwstra. There has been no direct contact between the infected poultry farms, which are also very far apart. All the farms, on the other hand, are in regions with large numbers of water birds. It is striking that the poultry on none of the infected farms has access to the outdoors, where the  birds could be infected by waterbirds. So how has it happened? ‘We suspect that the virus got into the barn on clothing or shoes carrying bird droppings, material from the farm or infected water,’ says CVI researcher Armin Elbers.


  • CVI sees infection via migrating birds as ‘likely’
  • Virus originates from China

Siberia

The bird flu virus subtype H8N8 originates from China, where it was isolated for the first time in 2009 in an apparently healthy batch of ducks on a poultry market. Research showed that the virus was highly virulent for chickens. Early this year the H5N8 virus spread fast across South Korea,  and migrating birds played a key role in that, Asian researchers established. An outbreak of H5N8 on a poultry farm in Japan in April was also blamed on migrating birds. At the beginning of November 2014, the infectious virus was found in droppings of Bewick’s tundra swans. This swan breeds in arctic zones such as Siberia, and from September starts to fly to its overwintering areas in north-west Europe, which include Great Britain, Denmark and the Netherlands. Soon after that, Germany was the first European country to report an outbreak of bird flu type H5N8 in turkeys.  


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