What is the possibility of HPAI H5N1 entering North America via migratory wild birds?
• Some migratory bird species move between North America, Asia and Europe. However, genetic studies of avian influenza viruses from Eurasia and North America suggest there is very limited exchange of AIVs between continents, even with very common influenza viruses. • It is not possible to discount the possibility of an HPAI H5N1 introduction, but such an event based on the known epidemiology of other avian influenza viruses is a low probability event. What is the possibility of this virus being maintained in wild bird populations? • There is limited scientific information on which to evaluate this possibility. • Experimental studies have demonstrated bird-to-bird transmission of HPAI H5N1 in mallards, but these studies were completed under confinement conditions that are not representative of natural conditions. • Experimental studies with HPAI H5N1 strains consistently have demonstrated higher respiratory rather than cloacal shedding of the virus. In wild birds, low pathology avian in
