Cross-species avian influenza among mammalians - report of fatal avian influenza in New England harbour sealsArchived
This academic article describes virological findings and pathological consequences of a strain of influenza A(H3N8) recently identified as part of the investigations of an outbreak of pneumonia among harbour seals in New England in the autumn.
Emergence of Fatal Avian Influenza in New England Harbor Seals Anthony SJ, St. Leger JA, Pugliares K, et al.American Society for Microbiology (mBio); 3(4): e00166-12; 31 July 2012
This academic article describes virological findings and pathological consequences of a strain of influenza A(H3N8) recently identified as part of the investigations of an outbreak of pneumonia among harbour seals in New England in the autumn. In total 162 animals, mostly young animals, died between September and December 2011. These findings led to the United States to declare the situation a federally recognized Unusual Mortality Event (UME) among the animals. The causative organism is an avian influenza which has been reported in waterfowl in the US since 2002. The viruses have mutations which the authors suggest are indicative of recent adaptation to mammals. These include a D701N mutation in the viral PB2 protein, previously reported in highly pathogenic A(H5N1) avian influenza viruses infecting people. Lectin staining and agglutination assays indicated the presence of the avian-preferred SAa-2,3 and mammalian SAa-2,6 receptors in seal respiratory tract, as well as the ability of the virus to agglutinate erythrocytes bearing either the SAa-2,3 or the SAa-2,6 receptor.(1)
ECDC Comment (1 August 2012): Seals are among the animals known to occasionally be infected with influenza A viruses including avian influenzas. Seal to seal transmissions take place and die-offs of seals like this have taken place in the past.(2) Since avian influenzas have their natural reservoir in water living birds seals presumably they come into contact with them on occasions. Though the authors suggest that the viruses are concerning because they acquired mutations that have been associated with increased transmissibility and virulence in mammals.(1) However modern influenza virological risk assessments are multi-dimensional and these finding are not that concerning in isolation from other observations such as infections in humans and the likelihood of human-animal contact.(3,4)
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