Mystery of Seal Strandings May Be Solved

Tests confirm dead seals in Maine had avian flu
By Arden Dier,  Newser Staff
Posted Jul 7, 2022 1:44 PM CDT
Seals Appear to Be Dying of Avian Flu
A harbor seal pokes its head out of the water in Casco Bay, July 30, 2020, off Portland, Maine.   (AP Photo/Robert F. Bukaty, File)

The avian flu epidemic appears to have claimed its first known marine mammal victims in North America. The US Department of Agriculture has confirmed four Maine seals who died or had to be euthanized tested positive for the virus, the National Oceanic and Atmospheric Administration said Tuesday. Officials tested the seals after noticing a sharp uptick in the number of strandings in Maine in June. Close to 60 gray and harbor seals have stranded, which is three times the normal rate for summer, the NOAA said, per the AP. Virtually all the seals were found dead or sick enough to be require euthanasia.

"The seal is the first marine mammal that we've seen on the spillover end," Dr. Julianna Lenoch, a national wildlife disease program coordinator for USDA, said at a Wednesday briefing, per the New York Times. "But this is not unexpected to have bird flu move into mammalian species on occasion." The strain of bird flu known as Eurasian H5N1 has devastated commercial poultry operations and wild bird populations, putting "carnivores and scavengers that feed on wild birds and their carcasses at risk," per the Times.

The virus has been found in North American mammals including foxes, bobcats, skunks, and raccoons, and in other European mammals, including otters. Seals, like otters, feed on seabirds. Though infected foxes have been shown to shed the virus, there's "no evidence of sustained mammal-to-mammal transmission," per the Times. Still, experts warn that the more chances the virus has to replicate in mammals, the better the chances of it transitioning from a bird virus to a mammalian one. Officials say the risk to humans in low, though people and their pets should stay away from seals. (Read more avian flu stories.)

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