Previously, EGG-NEWS has reported on mortality in marine birds on Marrowstone and Rat Islands in Puget Sound.  During the past week, the USDA- National Veterinary Services Laboratory confirmed that three harbor seals that died on Marrowstone Island during the last week of August yielded H5N1 strain avian influenza virus.

The sequence of marine birds dying of avian influenza followed by mortality in marine mammals has been documented on the northeast Atlantic coast of the U. S., along the southern Pacific coast of South America and in the Baltic Sea.

Hopefully, the virus isolated from seals will be sequenced to determine the specific mutations that have occurred allowing this strain to be infectious for marine mammals.  Surveillance is essential to monitor for the emergence of a potentially zoonotic strain of avian influenza virus.