On 23. 8. 2024, the highly pathogenic avian influenza virus H5N1 was confirmed at our workplace in a poultry farm in Chlum u Křemže in South Bohemia. The circulation of H5N1 during the summer months in our country and in Europe is very unusual and is due to the enzootic adaptation of the influenza virus in the wild bird population. This is an ecological change that we have been observing for several years.
A more detailed analysis of the virus has shown that the new H5N1 strain belongs to the AF genotype. The AF genotype is a resident European virus that has been circulating in the population since 2021 (2021/2022 season) and is regularly detected, albeit at low frequencies, in Central Europe.
The H5N1 AF virus was last confirmed in the Czech Republic in January 2023, the last influenza season. This variant has not been detected in the Czech Republic in the current season. According to the available data, the H5N1 AF viruses from Slovakia and Austria were last detected in December 2023. The H5N1 AF virus from Austria is evolutionarily closest to the Chlum strain. The Chlum outbreak shows that this H5N1 genotype continues to persist in our region and poses a potential risk to commercial and pet poultry farms in the future.
