OmniVira

Outbreak of Highly Pathogenic Avian Influenza A(H5N1) Virus in Seals, St. Lawrence Estuary, Quebec, Canada1.

Stéphane Lair Louise Quesnel Anthony V Signore Pauline Delnatte Carissa Embury-Hyatt Marie-Soleil Nadeau Oliver Lung Shannon T Ferrell Robert Michaud Yohannes Berhane
PMID38781927 DOI10.3201/eid3006.231033 Year2024 Journal Emerging infectious diseases Emerg Infect Dis Languageeng Statusppublish

Abstract

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.

Supporting text Virus Host Location
avian influenza 57 Canada 10 encephalitis 7 H5N1 82 highly pathogenic avian influenza 15 HPAI 19 influenza 61 pinnipeds 4 Quebec 2 respiratory infections 30 seals 2 St. Lawrence Estuary 1 unusual mortality event 1 viruses 117 Disease Outbreaks 170 Influenza A Virus, H5N1 Subtype 300 Animals 1948 Birds 212 Estuaries 1 Influenza in Birds 341 Orthomyxoviridae Infections 228 Phylogeny 805 Quebec 1 Seals, Earless 4

Evidence records

5 total
Zoonotic Surveillance
2 records · 2 evidence types
Evidence type Viral Detection
1 records
OVE8076 Viral Detection
Key finding

HPAI H5N1 viral genomes were detected in fifteen seals fatally infected during the St. Lawrence Estuary outbreak in Quebec, Canada.

Virus
Influenza A virus H5N1
Host
true seals Phocidae Natural host
Location
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. 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.

Method
genome sequencing | viral RNA detection
Sample type
necropsy specimens
Geographic raw
St. Lawrence Estuary, Quebec, Canada
Country inferred
CAN
Evidence type Reservoir Ecology
1 records
OVE8078 Reservoir Ecology
Key finding

Fatal infections of HPAI H5N1 in pinnipeds in Canada raised concerns about possible establishment of a marine mammal reservoir.

Virus
Influenza A virus H5N1
Host
pinnipeds Pinnipedia Natural host mammals Mammalia Natural host
Location
Canada
Supporting text

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.

Method
field surveillance | necropsy observations
Geographic raw
Canada
Country inferred
CAN
Transmission Evidence
2 records · 2 evidence types
Evidence type Outbreak Investigation
1 records
OVE8075 Outbreak Investigation
Key finding

An outbreak investigation documented fatal infections with highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b among harbor and gray seals in the St. Lawrence Estuary, Quebec, Canada, during 2022.

Virus
Influenza A virus H5N1
Host
harbor seal Phoca vitulina Natural host gray seal Halichoerus grypus Natural host birds Aves Natural host
Location
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.

Method
necropsy | histopathology | virus genome characterization
Transmission direction
animal-to-animal
Geographic raw
St. Lawrence Estuary, Quebec, Canada
Country inferred
CAN
Outbreak setting
seal haul-out sites in the St. Lawrence Estuary
Outbreak time
2022
Outbreak scale
Fifteen (56%) of the seals submitted for necropsy were fatally infected
Evidence type Cross-species Transmission
1 records
OVE8077 Cross-species Transmission
Key finding

HPAI H5N1 infection spilled over from infected birds to seals in the St. Lawrence Estuary, Quebec, Canada.

Virus
Influenza A virus H5N1
Host
true seals Phocidae Natural host birds Aves Natural host
Location
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 | virus detection | phylogenetic analysis
Study design
outbreak investigation and necropsy-based field study
Transmission direction
animal-to-animal
Geographic raw
St. Lawrence Estuary, Quebec, Canada
Genomic Evolution
1 records · 1 evidence types
Evidence type Phylogenetic Evolution
1 records
OVE8079 Phylogenetic Evolution
Key finding

HPAI H5N1 viruses from seals in the St. Lawrence Estuary showed fully Eurasian or Eurasian/North American genome constellations, indicating their phylogenetic lineage composition.

Virus
Influenza A virus H5N1
Host
true seals Phocidae Natural host
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.

Analysis methods
genome constellation analysis | phylogenetic comparison