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It really never left. Similar to the human influenza virus, avian influenza virus a.k.a. “bird flu” commonly re-emerges as a new strain from year to year.

Now we are seeing an interesting mix of viral strains spreading across the globe-lethal for birds but, at least for now, not people.

First, an H5N8 strain of avian influenza were identified in Asia and Europe, as reported by the World Organization for Animal Health (OIE).  Poultry in Germany, the Netherlands, and Britain were infected with an H5H8 strain similar to the strain that devastated poultry flocks in South Korea earlier this year.

Yesterday CBC news reported that an “avian flu virus involved in an outbreak in British Columbia is related to a deadly strain that has spread through Asia.”

The Canadian Food Inspection Agency  “determined the virus contains genes both from H5N2, which is common to North American wild birds, as well as genes from a high-path Eurasian strain of H5N8 . . .[adding that]  this is the first time a Eurasian lineage highly pathogenic H5 virus has caused an outbreak of avian influenza in poultry in North America.”

Now the H5N8 strain has been identified in a small backyard in Oregon.  This is reportedly the same strain just isolated from 2 wild birds in Washington State. Both state and national agricultural officials say there is no evidence of infection in commercial poultry farms in the U.S.

Influenza viruses are known for their re-assortment ability.  As CBS noted,  “the appearance of this particular re-assortant virus is significant due to its ability to cause high mortality in domestic poultry.”

The outbreak in Europe had been threatening to poultry farmers “along the Black Sea and East Atlantic migratory routes of wild birds” as Fox News recently reported.

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“FAO and OIE warned that although H5N8 had not been found in humans it was related to the H5N1 virus, which caused the deaths of nearly 400 people and hundreds of millions of poultry after it spread from Asia into Europe and Africa in 2005-2006.”

Countries are required to report animal health disease outbreaks to OIE, which serves as the international monitor and tracker of these events. OIE reports that a highly pathogenic strain H5N8 of avian influenza viruses (type A) “was detected early this year in Asia in poultry species in the Republic of Korea, Japan and in China . . . . The total of 29 outbreaks was reported in birds involving geese, chickens and ducks. Close to 600,000 birds were culled.”

The virus is commonly spread by migrating wild birds, and then, once introduced into domestic flocks, is transmitted through “direct contact with secretions from infected birds, especially feces or through contaminated feed, water, equipment, human clothing and shoes” and then is “readily transmitted from farm to farm by the movement of domestic live birds, people (especially when shoes and other clothing are contaminated), and contaminated vehicles, equipment, feed, and cages.”

That is why countries and states require stringent biosecurity measures to be implemented on poultry farms, particularly in the face of an outbreak.

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As recommended by OIE preventive measures at the farm level include:

  • keep poultry away from areas frequented by wild fowl;
  • do not provide elements on property that may attract wild birds;
  • keep control over access to poultry houses by people and equipment;
  • maintain sanitation of property, poultry houses and equipment;
  • avoid the introduction of birds of unknown disease status into flock;
  • report illness and death of birds to Veterinary Services;
  • appropriate disposal of manure and dead poultry;
  • vaccinate animals when appropriate.

This strain of the virus circulating in birds has not caused illness in humans.