The same migratory flyways that funneled H5N8 from Siberia, and China into Europe also extend into the Middle East, North Africa, and all the way to the West Central Coast. In 2014, H5N1 returned - almost certainly via that route - after an absence of more than 6 years.
With the surge of H5N8 into Europe and more recently into the Middle East, there has been concern the virus could make it all the way to West Central Africa. In early November, in FAO On HPAI H5's 4th Intercontinental Wave, they listed the following regions that were at risk:
Countries in the Middle East;
Countries in the EU;
Countries in the former Soviet Union;
Countries in South Asia.
Today the OIE posted notification of the first detection of HPAI H5N8 in West Africa - specifically Nigeria.
Clade 18.104.22.168 H5N8 has spread faster, and farther, than any other HPAI H5 virus we've seen to date. Along the way it has managed to reassort with local avian viruses, producing new, viable subtypes (H5N1, H5N2, etc.) in Taiwan and North America, and just recently H5N5 in Europe.
Its introduction into the Middle East and West Africa - places where H5N1 (and other avian viruses) are already endemic - adds another wild card to an already difficult situation.