HPAI H5N8 continues to expand its range, with the OIE reporting this morning the virus has recently been detected in a dead mute swan in Macedonia, very near the Turkish border.
The recent geographic expansion of HPAI H5N8 not only rivals, it exceeds, the great H5N1 diaspora of 2006. Over a two year period that virus jumped from 15 Southeast Asian countries to more than 60 countries across Europe and the Middle East.
While H5N1 eventually pulled back from much of its new found territory, it gained important footholds in the Middle East, India, and Africa.
Similarly, if not quite as impressively, we are seeing the expansion of HPAI H5N6 (another clade 18.104.22.168. H5 virus) in Asia, with the virus making major inroads in South Korea and Japan.
Exactly how these two viruses have suddenly taken flight is still a matter of conjecture, but both appear well suited for carriage by migratory birds, and both are rapidly evolving and diversifying, through both reassortment and antigenic shift.
A little over a month ago, in EID Journal: HPAI A(H5Nx) Viruses With Altered H5 Receptor-Binding Specificity, we looked at some of these genetic changes that may be aiding and abetting their recent expansion.