The H5N4 strain of avian influenza has been detected in the US for the first time this season, according to data from the World Organisation for Animal Health (WOAH). Up until this case, all other detected cases in North America have been infected by the H5N1 strain.
The case was first confirmed on September 15, but was initially reported on a list of H5N1 until it was discovered on October 17 that it was actually H5N4. The detected strain is a reassortant of the virus introduced to North America in December 2021 and the North American wild bird lineage.
US, Europe suffer from worst bird flu season on record
The case comes as North America and Europe continue to suffer from what is being called the worst bird flu season on record.
Nearly 48 million domesticated birds in 43 states and at least 3,124 wild birds in 46 states have been affected by the outbreak in the US.
Last week, an avian influenza prevention zone was declared across all of Great Britain, meaning that all bird keepers in the UK will be required to follow strict biosecurity measures in an effort to mitigate the outbreak.
The UK has been suffering from the largest outbreak it has ever experienced.
Earlier this month, Finland reported a case of the H5N5 strain of avian influenza for the first time in the country in a white-tailed eagle. H5N5 has also been detected in birds in Norway in the past year.
Minks in Galicia infected with bird flu
In Galicia, minks were found to be infected with the H5N1 strain of avian influenza earlier this month. Local health authorities decided to depopulate the mink farm. In late September, a man working at a poultry farm in the province of Guadalajara in Spain was found to be infected with H5N1 avian influenza. He was asymptomatic.
Avian influenza has been increasingly infecting mammals, such as foxes, seals, dolphins, skunks and bears, in the past year, although experts still estimate that the risk to humans remains low. In the current outbreak, only one person in the US, one person in the UK and one person in Spain have been infected with the virus. All three exhibited light symptoms and recovered fully.
Vietnam reports first human bird flu case in eight years
Additionally last week, Vietnam reported its first human case of avian influenza since 2014 when a 5-year-old girl was found to be infected with H5 avian influenza. (The exact subtype is still being figured out)
Meanwhile, in Nanning, Guangxi in China, a 3-year-old boy was found to be infected with the H5N6 subtype of avian influenza. The boy first developed symptoms in early September and is in serious condition, Hong Kong's Center for Health Protection announced last week. The center did not specify if the boy had been in contact with infected birds.
Last year, the H5N1 strain infected over one million birds in Israel.
Health officials have expressed concern that bird migrations in autumn will bring another spike in cases, with officials around the world, including in Israel, preparing for multiple possibilities.