Event Title First Global Alliance for Research on Avian Diseases (GARAD) Conference
Session Title Unknown
Event Date & Time On Mon, 29 Jun 2015 at 10:25:00 - 10:50:00
Venue Edmond J. Safra Lecture Theatre
Abstract Title The continuing evolution and threat of Asian H9N2 influenza viruses (Robert Webster)
Authors Robert Webster
Affiliations St Jude Children’s Research Hospital Memphis TN 38105, USA
Abstract Content

The H7N9 influenza virus that emerged in China in 2013, like H5N1, is a triple reassortant that causes severe human disease but causes no apparent disease in poultry. The H7N9 influenza viruses are more readily transmissible to humans than are the H5N1 viruses. H9N2 influenza viruses provided all six internal gene segments to the H5N1, H7N9 and to H10N8 viruses and may be the key influenza subtype that potentiates the transmission of these viruses to mammals including humans. H5N1 and H7N9 viruses continue to sporadically transmit from poultry to humans but to date continued human-to-human transmission has not occurred. The H9N2 influenza viruses in Bangladesh continue to evolve by reassortment with highly pathogenic H7N3 influenza viruses and by acquisition of multiple mutations that promote mammalian transmissibility. A surprising aspect of surveillance in the Bangladesh markets was that despite the co-circulation of H9N2 and highly pathogenic H5N1 very few reassortants were isolated, and disease signs in the poultry were inapparent.

The upsurge in human cases of H5N1 in Egypt is of continuing concern as is the global spread of the novel clade of H5N8 viruses throughout Eurasia and to the Americas. This suggests that there has been a paradigm shift in the ecology of influenza viruses in wild birds, and that some migratory species can transmit highly pathogenic viruses long distances.