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Literature detail

Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Virus in Seals, St. Lawrence Estuary, Quebec, Canada<sup>1</sup>.

Stéphane Lair Louise Quesnel Anthony V Signore Pauline Delnatte Carissa Embury-Hyatt Marie-Soleil Nadeau Oliver Lung Shannon T Ferrell Robert Michaud Yohannes Berhane
PMID 38781927 2024 Emerg Infect Dis eng ppublish
PubMed DOI Browse context

Article

Publication summary

We describe an unusual mortality event caused by a highly pathogenic avian influenza (HPAI) A(H5N1) virus clade 2.3.4.4b involving harbor (Phoca vitulina) and gray (Halichoerus grypus) seals in the St. Lawrence Estuary, Quebec, Canada, in 2022. Fifteen (56%) of the seals submitted for necropsy were considered to be fatally infected by HPAI H5N1 containing fully Eurasian or Eurasian/North American genome constellations. Concurrently, presence of large numbers of bird carcasses infected with HPAI H5N1 at seal haul-out sites most likely contributed to the spillover of infection to the seals. Histologic changes included meningoencephalitis (100%), fibrinosuppurative alveolitis, and multiorgan acute necrotizing inflammation. This report of fatal HPAI H5N1 infection in pinnipeds in Canada raises concerns about the expanding host of this virus, the potential for the establishment of a marine mammal reservoir, and the public health risks associated with spillover to mammals.Nous décrivons un événement de mortalité inhabituelle causé par un virus de l'influenza aviaire hautement pathogène A(H5N1) clade 2.3.4.4b chez des phoques communs (Phoca vitulina) et gris (Halichoerus grypus) dans l'estuaire du Saint-Laurent au Québec, Canada, en 2022. Quinze (56%) des phoques soumis pour nécropsie ont été considérés comme étant fatalement infectés par le virus H5N1 de lignées eurasiennes ou de réassortiment eurasiennes/nord-américaines. Un grand nombre simultané de carcasses d'oiseaux infectés par le H5N1 sur les sites d'échouement a probablement contribué à la contamination de ces phoques. Les changements histologiques associés à cette infection incluaient : méningo-encéphalite (100%), alvéolite fibrinosuppurée et inflammation nécrosante aiguë multi-organique. Cette documentation soulève des préoccupations quant à l'émergence de virus mortels, à la possibilité d'établissement de réservoirs chez les mammifères marins, et aux risques pour la santé publique associés aux propagations du virus chez les mammifères.

avian influenza Canada encephalitis H5N1 highly pathogenic avian influenza HPAI influenza pinnipeds Quebec respiratory infections seals St. Lawrence Estuary unusual mortality event viruses Disease Outbreaks Influenza A Virus, H5N1 Subtype Animals Birds

Structured evidence records

Evidence records

4 total
Cross Species Transmission 1 records
Cross Species Transmission Extraction confidence 0.95
Key finding

HPAI H5N1 was transmitted from infected birds to harbor and gray seals in Quebec, Canada, during a 2022 mortality event.

Virus
IAV H5N1
Location
Canada Canada
Supporting text

Concurrent presence of large numbers of bird carcasses infected with HPAI H5N1 at seal haul-out sites most likely contributed to the spillover of infection to the seals.

Method
necropsy; phylogenetic analysis
Study design
outbreak investigation
Transmission direction
animal-to-animal
Geographic raw
St. Lawrence Estuary, Quebec, Canada
Country inferred
Canada
Outbreak Investigation 1 records
Outbreak Investigation Extraction confidence 0.90
Key finding

An outbreak of HPAI A(H5N1) infection occurred among harbor and gray seals in the St. Lawrence Estuary, Canada, in 2022, probably linked to exposure to infected bird carcasses.

Virus
IAV H5N1
Location
Canada Canada
Supporting text

We describe an unusual mortality event caused by a highly pathogenic avian influenza (HPAI) A(H5N1) virus clade 2.3.4.4b involving harbor (Phoca vitulina) and gray (Halichoerus grypus) seals in the St. Lawrence Estuary, Quebec, Canada, in 2022. Concurrently, presence of large numbers of bird carcasses infected with HPAI H5N1 at seal haul-out sites most likely contributed to the spillover of infection to the seals.

Method
necropsy; histology; genomic characterization; phylogenetic analysis
Transmission direction
animal-to-animal
Geographic raw
St. Lawrence Estuary, Quebec, Canada
Country inferred
Canada
Outbreak setting
seal haul-out sites in the St. Lawrence Estuary
Outbreak time
2022
Outbreak scale
15 (56%) of the seals submitted for necropsy were considered to be fatally infected
Recombination Or Reassortment 1 records
Recombination Or Reassortment Extraction confidence 0.85
Key finding

HPAI H5N1 viruses infecting seals showed fully Eurasian or Eurasian/North American genome constellations, demonstrating reassortment between Eurasian and North American lineages in a cross-species transmission event.

Host
Not specified
Location
Not specified
Supporting text

Fifteen (56%) of the seals submitted for necropsy were considered to be fatally infected by HPAI H5N1 containing fully Eurasian or Eurasian/North American genome constellations.

Event type
reassortment
Spillover Event 1 records
Spillover Event Extraction confidence 0.98
Key finding

HPAI A(H5N1) likely spilled over from infected birds to seals in the St. Lawrence Estuary, Quebec, Canada.

Virus
IAV H5N1
Host
Phocidae Aves
Location
Canada Canada
Supporting text

Concurrent presence of large numbers of bird carcasses infected with HPAI H5N1 at seal haul-out sites most likely contributed to the spillover of infection to the seals.

Method
necropsy; genomic analysis; histology
Study design
outbreak investigation
Transmission direction
animal-to-human
Geographic raw
St. Lawrence Estuary, Quebec, Canada
Country inferred
Canada