23.08.2013

Emerg Infect Dis Vol. 19, No. 9, September 2013

Human infection with avian influenza A(H9N2) virus was identified in Bangladesh in 2011. Surveillance for influenza viruses in apparently healthy poultry in live-bird markets in Bangladesh during 2008–2011 showed that subtype H9N2 viruses are isolated year-round, whereas highly pathogenic subtype H5N1 viruses are co-isolated with subtype H9N2 primarily during the winter months. Phylogenetic analysis revealed that the H9N2 viruses were reassortants that contained genetic material from H7N3 viruses but no material from H5N1 viruses, but no reassortment with subtype H5N1 viruses. Molecular analysis showed that multiple mammalian-specific mutations have become fixed in the subtype H9N2 viruses, including changes in the hemagglutinin, matrix, and polymerase proteins. These results indicate that these viruses could mutate to be transmissible from birds to mammals, including humans.

 

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