The researchers concluded that there is a shift in the highly pathogenic avian influenza (HPAI) H5 subtype’s epicentre that goes beyond Asia, where it first emerged in 1996, and indicate that the spread of the virus in wild birds is facilitating geographic and host range expansion.

The virus spread in 2005 through migratory birds coming from China to Egypt, where it was declared an epidemic in 2006. Egypt declared an epidemic in 2006, when “that voracious variant wiped out entire farms, and infected about 359 humans,” says Rabeh Al-Shishini, virologist at Egypt’s National Research Centre (NRC), and co-author of the study.

At the time, Egypt began vaccinating poultry with vaccines against that avian influenza subvariant, but it became endemic in Egypt until 2017, when poultry and wild birds were infected with another bird flu subvariant called H5N8 that further caused a global spike in 2020 and 2021.“The 2016 and 2017 outbreak in Egypt is attributable to multiple reasons, including the absence of effective vaccines against the prevailing bird flu variants,” says Al-Shishini.

The newest H5N1 strain taking over the world has evolved from, and almost entirely replaced, the H5N8 stain that emerged in Egypt in 2016. The current outbreak is caused by two subtypes; one that spread in the northern coastal regions of central Europe and then on to North America by migrating birds, and the other in the Mediterranean Sea and subsequently in Africa.

https://www.natureasia.com/en/nmiddleeast/article/10.1038/nmiddleeast.2024.71