Lokkilinnuissa (LARUS sp. LARIDAE) on LPAIV muuttunut neljän viime vuoden aikana HPAIV lintuflunssamuotoon muotoon ja H5Nx lintuviruksia on niissä esiintynyt ja ne toimivat ilmeisesti luonnollisena säiliönä lintuinfluenssaviruksille. https://www.biorxiv.org/content/10.1101/2023.02.17.528990v1.full.pdf
Discussion
During the 2020-2021 and 2021-2022 outbreaks of high pathogenicity avian influenza in the UK, there has been an increased detection of HPAIV H5N1 in seabirds of the Orders Suliformes (Suulalinnut, sulor,Sulidae) and Laridae (Lokkilinnut, måsar, trutar)) . 3,6,16,34 This investigation of naturally acquired infection revealed that gross pathology was limited to pancreatic necrosis in the herring gull (Larus argentus,Harmaalokki, Gråtrut, Soelvmåge, Silbermöwe ) and proventricular ulceration in the great skua (.Stercorarius skua, Isokihu, Storlabben, Storkjove Grosse Raubmöve)) The pancreatic changes were less characteristic compared to that in Galliformes ( Domestic fowls, Kanalinnut, Hönsfåglar,Hoensefugle) and Anseriformes ( Sorsalinnut, Andfåglar, Andefugle, Gooselike fowls), and required immunohistochemical confirmation. Microscopic evaluation confirmed a multi-systemic HPAIV infection including neuro-, cardio, and pneumo-tropism, which may have been contributary to the mortalities seen. In addition, acute reproductive damage in female great skuas’ (Stercorarius skua,) was noted. Overall, seabirds (merilinnut, sjöfåglar, havfugle) are highly susceptible t odeveloping pathologies in multiple organ systems following HPAIV infection.
Historically, gull species ( LARUS species, lokkilajit, måsar och trutar, måger och tore måger, gulls) from the Order Laridae have been associated with infection with LPAIV including H11, H13 and H16 subtypes. These infections have been predominantly associated with replication in epithelial cells of intestine that has been hypothesised to facilitate faecal-oral transmission in black headed gulls (Larus ridibundus, Naurulokki, Skrattmås, Häettemåge, Lachmöwe) . For HPAIV, natural infection has been reported in great skuas (Stercorarius skua) , European herring gulls (Larus argentatus,), black-headed gulls (Larus ridibundus) , and great black-backed gulls (Larus marinus, Merilokki, Havstruten, Svartbag, Mantelmöwe)
The most common and severe pathology in all birds examined was pancreatic necrosis associated with viral infection (except for in the black-headed gull (L.ridibundus) where the pancreas was unavailable), followed by splenic necrosis and pneumonia (except in the long tailed skua, Stercorarius longicaudus, Tunturikihu,Fjällabb, ). Such lesions are like those reported from experimentally challenged common gulls (Larus canus, Kalalokki, Fiskmås, Stormmåge, Sturmmöwe) (with H5N1, plus naturally infected black headed gulls (L.ridibundus) and herring gulls (L. argentatus) , together with a recent report of naturally infected sandwich terns (Thalasseus sandvicensis);( Riuttatiira, Kentsk tärna, Sterna sandvicensis?) . Although RT-PCR was not conducted on tissues from the current investigation, the abundance of virus antigens in the heart, brain, kidney, spleen, lung, pancreas, and liver strongly suggests the utility of these organs for diagnostic evaluation. It has been proposed that the enterotropic adaptation of HPAIV in wild waterbirds ( villit vesilinnut) has facilitated long term persistence and dissemination in these species with virus being maintained in stable equilibrium without undue pathological impact on the host. 10,11
In this report, we noted higher level of immunolabelling in the trachea, proventriculus, gizzard and duodenum in the great skua, and additionally antigens detected in the respiratory and enteric epithelium, which were generally absent in the previous GB epizootic in great skua in 2021.
Similar respiratory and enterotropism was observed in the long tailed skua, herring gull and black-headed gull in this study. The nasal turbinates were only examined in the herring gull which showed viral associated rhinitis and epitheliotropism. Previously, infection of the intestine had only been observed rarely with H5N1 clade 2.2 viruses in common gulls 23 and a laughing
gull (Leucopheus atricilla,Larus atricilla, Naurulokki P.Amerikassa, Lattermåge) infected with an ‘Eurasian-lineage’ of H5N1.
Avian influenza viruses preferentially bind the α-2,3 sialic acid residues. 13
Based on lectin histochemistry on other gull species including American herring gulls (Larus smithsonianus), laughing gulls (Leucophaeus atricilla, Laridae ) and (Larus delawarensis), the respiratory epithelium express both α-2,3 and α-2,6 sialic acids, whereas the intestinal tracts express predominantly α-2,3 and rarely α-2,6 sialic acids.
The pathway of incursion in free-ranging seabirds is not understood but has been proposed to be either independent incursion or onward introductions from species movements between colonies and the movement of seabirds between mainland and islands particularly during the breeding season. Herring gull and great skua can opportunistically predate or scavenge on other birds and this was observe in the outbreak in gannet colonies. Further, contact transmission between common
gulls (Larus canus) and European herring gulls have been documented previously with experimental infection with HPAIV H5N1 clade 2.2 and H5N8 clade 2.3.4.4b. 23,46
More recent HPAIV H5N1 outbreaks (June and August 2022) in wild bird (villilinnut) rescue centres / hospitals in England (East Sussex and Cornwall) have been confirmed in herring gulls. After epidemiological assessment, the most likely source of infection appeared to be the introduction within the premises of infected / diseased herring gulls which had then transmitted the disease to the resident gulls of the same species within and among enclosures (APHA, unpublished data). It is not uncommon for skuas (KIHUT, labbar) or gulls (LOKIT, måsar och trutar, måger) to congregate in high densities during the breeding season for nesting, feeding and bathing facilitate close contact. These behaviors could facilitate dissemination of HPAIV especially if virus replication is prominent in respiratory and intestinal tracts. Infections through such contact can lead to birds from other colonies becoming exposed and infected, which then themselves spread virus to new localities and susceptible avian species. Further, these seabirds (MERILINNUT, sjöfåglar, havfugle )are often in areas with high seal (hylkeet, sälar) populations plus other scavenging mammals (imettäväiset, nisäkäseläimet) that can predate on sick or dead birds, and result in exposures of other host population types to infectious materials either directly or indirectly through the environment.
The distribution and ecology of seabird populations also challenge the current understanding of HPAIV transmission at a global level. Both long tailed skua and
great skua are transitory migrant birds - long tailed skuas are a passage migrant in
the UK and breed in Arctic region, whereas great skuas migrate to the
northernmost isles of the UK in summer for breeding and return to the coasts of Spain and Africa, and as far as Brazilian and Argentinian coasts for wintering
Black-headed gulls are found across the UK, 28 and herring gulls are found throughout the year around the UK coastline and inland around rubbish tips, fields,large reservoirs, and lakes, especially during the winter months.
Recent ring recovery data revealed that great skua, European herring gulls and black-headed
gulls migrate between Europe to Iceland and other North Atlantic islands, and to North America. The pelagic and migratory nature of gulls have led to suggestion of intercontinental dissemination and shaping of influenza A virus evolution. Apart from the increased mortality in seabirds during 2022 which has resulted in an immediate impact upon populations, there is generally a significant deficit in knowledge on the impact of infectious diseases on population structures across these species. However, a trend towards a reduction in breeding abundance in the UK for herring gulls, black-headed gulls and great skuas has been noted.
The pathogenic mechanism of HPAIV on reproductive organs of wild bird is poorlydocumented. Previous reports have demonstrated epithelial labelling of virus antigen in the oviduct of common buzzards ( Buteo buteo, Accipitridae , Päiväpetolinnut, Hiirihaukka, Ormvråk, Musvåge) and peregrine falcons ( Falco peregrinus, Falconidae, Muuttohaukka, Pilgrimsfalk, Vandrefalk), infected with HPAIV. In domestic poultry, both HPAIV and LPAIV infection can lead to short to long term reduction in egg production or embryonic death because of viral-induced pathology on the ovaries, oviduct, or conceptus. There has been an increased detection of reproductive pathologies in laying poultry (siipikarja, fjäderfä), both Galliformes (Kanalinnut, hönsfåglar)and Anseriformes ( sorsalinnut, andfåglar , andefugle) during the 2022 epizootic season in the UK which can be attributed to virus infection in situ (Lean F, unpublished). However, the impact on the poultry sector, where an abundance of eggs is produced daily, cannot be compared to seasonal reproductive cycle in seabirds (merilinnut, sjöfåglar, havfugle) and as such the longer-term impact on population densities for these species will require monitoring to assess population recovery. In conclusion we demonstrate the susceptibility and pathology of a subset of Laridae (lokkilinnut, måsar och trutar, måger)
and Suliformes (Suulalinnut, Sulor, Suler, Basstölpel)) following a naturally acquired infection with HPAIV H5N1 clade 2.3.4.4b.
We associate rapid mortality with the observed multisystemic dissemination of viral antigen and resultant tissue damage. Reproductive pathology is also noted amongst the female great skua(Stercorarius skua, isokihu, Storlabben, Storkjove) but the longer-term impact on population fecundity warrants further investigation
Mainittuja lintulajeja:
CHARADRIIFORMES , Kahlaajalinnut, Vadarfåglar el.vadarna
STERCORARIIDAE, Kihut, Labbar, Kjöver
LARIDAE Lokit, Måsar och trutar, Möger
STERNIDAE, Tiirat, Tärnor , Terner
GALLIFORMES kesyt (siipikarja), fjäderfä, Hönsfåglar, ja villit kanalinnut, Vilda hönsfåglar
ANSERIFORMES, Sorsalinnut, Andgålar, Andefugle
ACCIPITRIFORMES Päiväpetolinnut
ACCIPITRIDAE, Kotkat, Haukat, Örnar, Hökar, Vråkar
FALCONIDAE, Jalohaukat , Falkfåglar
Koetan tässä katsoa lintulajeille nimiä latinaksi, suomeksi, ruotsiksi, tanskaksi ja jopa saksaksi, jos mahdollsita. Paikkailen tätä luetteloa vielä. 28.7. 2023
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