Research Article

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)
15.5Wild 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)
0.5Poultry-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)
7.3Poultry-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.