On November 5th, authorities in South Korea reported isolations of H5N1 highly pathogenic strain avian influenza virus from a mallard and a mandarin duck both found dead on October 26th.  The two cases were separated by a distance of approximately 100 miles, suggesting widespread infection in migratory waterfowl. 

In a comment, ProMED noted, “The dynamics of the spread of influenza virus is extremely complex and difficult to predict.  Several factors can influence it, such as the wild bird migration pattern, unregulated trade, farming systems, biosecurity and an immune status.”  The comment continued, “During the Northern Hemisphere winter wild bird movements may increase and lower temperature may facilitate the environmental survival of avian influenza virus increasing exposure of poultry.  Mixing of wild birds from different geographic origins during migration can increase the risk of virus spread and genetic reassortment resulting in changes in viral properties.”

South Korea is currently restoring flocks heavily impacted by avian influenza in late 2020.  For the first nine months of 2021 South Korea ranked third among importers of shell eggs receiving 37.3 million dozen commencing in February 2021 and amounting to $37.3 million dozen valued at $45.8 million through September.  South Korea is also the third largest importer of egg products with 4,401 metric tons shipped for the first nine months of 2021 valued at $10.8 million.

If South Korea is impacted with avian influenza again requiring depletion of flocks, it is anticipated that exports will continue and will not decline as would be the case with restoration of flocks without a new exposure to the disease.  Should avian influenza become endemic authorities might consider vaccination as an alternative to flock depletion given the previous history of extensive losses resulting in a high cost to the government and to consumers.