European Seals Dying of Influenza A(H10N7)

In 2011 seals in New England (USA) died, which was eventually linked to an infection with Influenza A(H3N8) Virus. See here. Before it appeared in seals, the Influenza A(H3N8) Virus was known as an avian adapted virus and was commonly found in the digestive and respiratory tracts of birds: alpha 2,3 receptor cells. But in these seals the virus had adapted to the mammalian alpha 2,6 receptor cells, the type also found in the human upper respiratory tract[1].

In recent weeks there have been reports of large die offs of seals in Denmark and Germany, and it was determined that a combination of an infection with avian Influenza(H10N7) Virus, pneumonia, and bacterial infections were behind these deaths[2].

[Image: www.emeral-vision.com]

Professor Lars Erik Larsen of the Section of Virology at the National Veterinary Institute explains: 'The Influenza virus weakens the seals, thus becoming more susceptible to other infections which may contribute to the deterioration of the disease and possibly lead to seals dying. Initially, the seals probably got the flu by being in contact with birds or their droppings.'

Nothing to worry about, you might say at this point. Some seals might be dying, but there are some worrying aspects to this news, because Influenza A(H10N7) Virus is also able infect humans. Some cases of such an infection appeared from countries like Egypt (2004) (pdf here) and Australia (2012)[3]. Given its limited history of infecting humans, and the mild symptoms it has provoked, Influenza A(H10N7) Virus seems an unlikely candidate to cause a serious epidemic threat.

But, like all Influenza A viruses, Influenza A(H10N7) has the ability to drift, mutate, or reassort with other influenza viruses and – over time - continually re-invent itself.

[1] Anthony et al: Emergence of Fatal Avian Influenza in New England Harbor Seals in mBio – 2012
[2] DTU Veterinærinstituttet: Sæler fra flere områder af Danmark smittet med influenza. See here.
Arzey et al: Influenza virus A (H10N7) in chickens and poultry abattoir workers, Australia in Emerging Infectious Diseases - 2012