The largest-ever bird flu outbreak, which began in 2021, has originated in Europe and Africa, marking a shift away from the typical origin in Asia. The subtype of the bird flu virus responsible for this outbreak is called H5N1 and has infected and killed a record number of both domestic and wild birds worldwide. H5N1 was first detected in China in 1996 and remained largely in South-East Asia until 2005, when it spread to Africa, the Middle East, and Europe. The virus re-emerged in 2021, affecting birds in North America, Europe, Asia, and Africa, and has also spread to some mammals and a few humans. Richard Webby, a researcher at St. Jude Children's Research Hospital, notes that there is something different about the recent viruses compared to previous ones. The amount of the virus in wild birds is unprecedented.
Researchers have analyzed bird flu outbreaks between 2005 and 2022 to understand the recent spread of H5N1. They collected data on confirmed cases from international organizations and obtained genetic information on bird flu viruses. The analysis revealed that the H5N1 virus responsible for the 2021 outbreaks and onward can be traced back to another subtype of the bird flu virus, H5N8, which originated in Northern Africa. This virus evolved into the current H5N1 virus in wild European birds and then spread to cause widespread outbreaks in domestic and wild birds in many countries.
This shift in the epicenter of bird flu evolution from South-East Asia to Europe and Africa suggests that other countries should increase their surveillance efforts, particularly in Africa where infrastructure is lacking. Careful vigilance is crucial for understanding the circulating bird flu viruses and guiding vaccine development and transmission control efforts. Bird flu currently cannot transmit between people, but humans can contract it by interacting with infected animals. Increased surveillance can help warn people in affected areas about contact with sick animals and reduce the potential for a pandemic emergency.
By identifying places of spillover and reducing spillover in humans, the risk of a bird flu pandemic can be minimized. Understanding the evolving nature of the virus and its potential to spread in humans is essential for preparedness and response measures.