Three weeks ago, in NOAA Investigating Unusual Seal Strandings & Deaths In New England we looked at reports of an unusual spike in seal mortality along the Maine, New Hampshire, and Massachusetts coastlines, which was reminiscent of a 2011 event caused by a novel H3N8 avian flu (see New England Seal Deaths Tied to H3N8 Flu Virus).
That 2011 outbreak caused considerable stir, both in the press and the scientific community, because the virus was shown to have acquired significant mammalian adaptations (see Nature Communications: Respiratory Transmission of Avian H3N8 In Ferrets).
Roughly two weeks ago, avian influenza (subtype not specified), along with Phocine Distemper virus, was confirmed as being present in at least some of the seals recovered in this latest die off (see NOAA: Seals in New England Test Positive for Avian Flu & Phocine Distemper Virus).
Last Friday NOAA Fisheries declared a UME (Unusual Mortality Event) among penipeds in the Northeast, along with a second UME among bottlenosed dolphins in Southwest Florida linked to a Red Tide outbreak.
We’ve a 51 minute audio file of a press conference held by NOAA Fisheries, followed by a brief written statement (below).
The $64 question still outstanding is what subtype of avian influenza was detected in these seals? And for that, we still have no answers. During the 2011 outbreak it took roughly 6 weeks after influenza A was announced before we learned it was due to H3N8.
Although the risk is likely low, the public is being urged not to approach within 100 yards of dead, sick, or stranded seals, and to keep all pets on a leash to prevent contact.
Since July 2018, elevated numbers of harbor seal and gray seal mortalities have occurred across Maine, New Hampshire and Massachusetts. This event has been declared an Unusual Mortality Event (UME).
Since July 2018, elevated numbers of harbor seal (Phoca vitulina) and gray seal (Halichoerus grypus) mortalities have occurred across Maine, New Hampshire and Massachusetts. This event has been declared an Unusual Mortality Event (UME).
Why are seals stranding?
Full or partial necropsy examinations have been conducted on several of the seals and samples have been collected for testing. Preliminary testing has found some seals positive for either avian influenza or phocine distemper virus. We have many more samples to process and analyze, so it is still too soon to determine if either or both of these viruses are the primary cause of the mortality event.
As part of the UME investigation process, an independent team of scientists (Investigative Team) is being assembled to coordinate with the Working Group on Marine Mammal Unusual Mortality Events to review the data collected and provide guidance for the investigation.
How can I help?
Report a stranded or floating seal
The most important step members of the public can take to assist investigators is to immediately report any sightings of live seals in distress or dead seals. Make the report by calling the NOAA hotline at 866-755-NOAA (6622) or by contacting your local marine mammal stranding network member by visiting our Stranding Network web page for local contact information.
Please, do not approach or touch the seal.
For some past blogs on influenza in seals, you may wish to revisit: