Phylogenetic and Molecular Characteristics of Wild Bird-Origin Avian Influenza Viruses Circulating in Poland in 2018−2022: Reassortment, Multiple Introductions, and Wild Bird–Poultry Epidemiological Links

Table 2

Epidemiological links between H5N8 HPAIV outbreaks in wild birds and poultry during the H5Nx HPAI 2020/2021 season in Poland.

Wild bird (collection date, species)	Poultry; (collection date)	Distance (km)	Suspected virus transmission route
MB128/20; (8 December 2020, tundra bean goose)	A/turkey/Poland/475/2020; (3 December 2020)	15.5	Wild bird-to-poultry-spillover of HPAIV as the primary virus introduction, followed by a secondary virus spread within the area
	A/chicken/Poland/476/2020; (4 December 2020)	8.7
MB129/21; (19 February 2021, buzzard)	A/turkey/Poland/116/2021; (11 February 2021)	0.5	Poultry-to-wild bird spillover of HPAIV due to the buzzard’s predatory behavior in the HPAIV-contaminated area
MB412/21; (2 May 2021, white stork)	A/chicken/Poland/H293/2021; (23 March 2021)	7.3	Poultry-to-wild bird spillover of HPAIV due to the high infection pressure resulting from the massive environment contamination with HPAIV
	A/chicken/Poland/H712/2021; (16 April 2021)	19.3
	A/chicken/Poland/H928/202; (25 April 2021)	39.7
	A/chicken/Poland/H984/2021; (28 April 2021)	9.5
	A/chicken/Poland/H1084/2021 (07 May 2021)	33.7
	A/chicken/Poland/H1161/2021; (13 May 2021)	4.5
	A/turkey/Poland/H1168/2021; (13 May 2021)	56
	A/turkey/Poland/H1184/2021; (14 May 2021)	70
	A/turkey/Poland/H1289/2021; (24 May 2021)	176

Straight line distance between HPAIV-positive poultry farms and collection spots of dead wild birds is given. The sequence names of H5N8 HPAIV obtained from poultry include the host species.