Pathology of naturally acquired high pathogenicity avian influenza virus H5N1 infection in seabirds

Abstract

The re-emergence of the high pathogenicity avian influenza virus (HPAIV) subtype H5N1 in the United Kingdom in 2021-2022 has caused unprecedented epizootic events in wild birds and poultry. During the summer of 2022 there was a shift in virus transmission dynamics resulting in increased HPAIV infection in seabirds and consequently a profound impact on seabird populations. To understand the pathological impact of HPAIV in seabirds, we have evaluated the virus distribution and associated pathological changes in the tissues of great skua (Stercorarius skua, n=8), long tailed skua (Stercorarius longicaudus, n=1), European herring gull (Larus argentatus, n=5), and black-headed gull (Chroicocephalus ridibundus, n=4). Grossly there was gizzard ulceration in one great skua and pancreatic necrosis in four herring gulls, which were confirmed for virus infection in situ by immunohistochemistry. Microscopical analysis revealed neuro-, pneumo-, lymphoid- and cardiotropism of HPAIV H5N1, with the most common virus-associated pathological changes being pancreatic and splenic necrosis. Examination of the reproductive tract of the great skua revealed HPAIV-associated oophoritis and salpingitis, and virus replication within the oviductal epithelium. Across the birds, epitheliotropism was evident in the intestine, nasal turbinate, and trachea. This was, in contrast, not observed in the 2021 summer mortality event in great skuas and may be significant for the disease epidemiology observed in 2022. The emergence of HPAIV in seabirds, particularly during summer 2022, has challenged the dogma of HPAIV dynamics, posing a significant threat to wild bird life with potential implications to the reproductive performance of seabirds of conservation importance.

Fulmar Litter Monitoring in the UK : Update 2022

“…The relative low number of fulmars collected in year 2022 is mainly a consequence of the major outbreak of highly pathogenic avian influenza (HPAI) in seabirds. Considerable mortality was observed among great skuas (Stercorarius skua), Sandwich terns (Thalasseus sandvicensis) and northern gannets (Morus bassanus) in the UK (Camphuysen et al 2022;Lane et al 2023;Knief et al 2023).…”

Pinnipeds and avian influenza: a global timeline and review of research on the impact of highly pathogenic avian influenza on pinniped populations with particular reference to the endangered Caspian seal (Pusa caspica)

“…Laridae (gulls and terns in particular) constitute one of the principal reservoirs of AIVs. Their eco-geographic role in the global dynamics of the spread of AIVs, are significant but yet distinct from those of wild waterfowl (Kawaoka et al, 1988;Perkins and Swayne, 2002;Fouchier et al, 2005;Wille et al, 2011a;Ratanakorn et al, 2012;Tønnessen et al, 2013;Verhagen et al, 2014;Wille et al, 2014;Arnal et al, 2015;Benkaroun et al, 2016;Lang et al, 2016;Alkie et al, 2022Alkie et al, , 2023Lean et al, 2023). Although gulls are mainly vectors for the H13 and H16 subtypes, they have been shown to also be infected by other subtypes.…”

The A(H5N1) Avian Influenza Virus at the Domestic Animal-Wildlife-Human Interface

“…I have read with great interest the nice article by Dr Fabian ZX Lean et al, describing the pathology of naturally acquired high pathogenicity avian influenza (HPAI) virus A(H5N1) infection in seabirds (1). Indeed, following its first appearance over 25 years ago among domestic birds (ducks and chickens) in South-Eastern Asia, the aforementioned viral pathogen has alarmingly emerged, once again, in the global ecoepidemiological scenario.…”