Since highly pathogenic avian influenza (HPAI) is commonly spread by migrating birds, there is a possibility that the strain of HPAI that has affected about 240 commercial poultry flocks in the United States and Canada could spread to poultry in Central America and South America.

But Dr. David E. Swayne, laboratory director of the U.S. Department of Agriculture’s in-house high biocontainment laboratory for poultry health research, indicated that it may not be very likely. Swayne answered a related question during the webinar, Facts About Highly Pathogenic Avian Influenza Spread and Control, hosted by and sponsored by Boehringer Ingelheim on May 26.

Swayne was asked if the H5N1 virus in North America could persist in wild ducks or other migrating birds and spread further south. His short answer was “we don’t know what will happen,” but he did explain while it could be possible. He used the HPAI outbreak of 2014-2015 as a point of reference.

In that outbreak, the last confirmed case in commercial poultry occurred in June 2015, but he said surveillance of wild birds showed the presence of the virus until the end of 2016.

He noted that there appears to be a higher infection rate in migratory water fowl during this outbreak than the 2014-2015 outbreak, and wildlife agencies will continue to monitor the situation even after the virus is no longer affecting commercial poultry.

However, taking into account migratory patterns of most wild birds, the possibility seems limited.


“Although there are connections in many of the flyways from North America and South America, there are fewer birds in those flyways that fly from North America to Central America and South America,” he said.

However, there are some dabbling ducks and terns that will migrate that far south, so it could still happen, Swayne said.

“It’s up to multiple entities to continue that surveillance to be looking for it, but at this point we don’t know much,” he said.

An archived version of the webinar can be accessed on Register to attend the webinar.

To learn more about HPAI cases in North American commercial poultry flocks, see an interactive map on

Read our ongoing coverage of the global avian influenza outbreak.