A week ago, in Russia: Mass Mortality Event (Seals) In Caspian Sea Linked To Avian Flu we looked at the mass die off of (reportedly) 2,500 seals last December in the Caspian Sea, and a report from Dagestan State University stating that an (as yet unsubtyped) avian influenza A virus was detected in the carcasses of the seals they tested.
While H5N1 was not confirmed, it was mentioned in their statement as a likely cause.
In contrast, yesterday Russia's Federal Service for Veterinary and Phytosanitary Surveillance (Rosselkhoznadzor) announced they were unable to confirm those test results, and have asked the Dagestan State University to provide biological samples of what they tested.
First the (translated) statement from the Russian agency, then I'll return with a postscript.
Rosselkhoznadzor did not detect avian influenza and other infectious diseases in seals killed on the coast of the Caspian Sea
The main thing January 30, 2023
In early December 2022, dead seals (Caspian seal, lat. Pusa caspica ) were found in the coastal strip of the Caspian Sea in the Republic of Dagestan.
In order to conduct a survey, assess the epizootic situation and find out the causes of the case, experts from the FGBI “Federal Center for Animal Health” (FGBI “ARRIAH”) were sent to the Republic of Dagestan on an expeditious basis.
The samples taken by them together with the inspectors of the Rosselkhoznadzor from the dead individuals were delivered to the FGBI "ARRIAH" and subjected to comprehensive studies.
The pathological material was tested by PCR for the presence of influenza viruses type A and subtype H5, rabies, adeno-, parvo-, morbili-, capripox- and orthopoxviruses, SARS-CoV-2, as well as bacteria that cause pasteurellosis, mycoplasmosis, clostridiosis, chlamydia and brucellosis.
As a result of the research, the listed diseases that can occur in the form of epizootics and cause the death of animals and birds are completely excluded.
At the same time, on January 24, the Dagestan State University, citing the Institute of Ecology and Sustainable Development , reported that bird flu could be the preliminary cause of the death of the seals.
Rosselkhoznadzor does not confirm this information. In order to clarify the circumstances that led to such conclusions, an appeal was sent to the indicated institute with a request to organize the sending of samples of pathological material to the reference laboratory for viral diseases of birds of the FGBI “ARRIAH” to confirm the diagnosis.
So far, no response has been received from the Institute of Ecology and Sustainable Development of DSU.
Missing from this report are the collection dates for the samples tested by the Rosselkhoznadzor lab (Dagestan University reportedly collected their samples sometime in December). It is possible that the samples collected by the Federal agency had simply degraded over time, and were therefore unable to yield a positive result.
It is notable that the results for all of the `usual suspects' for an epizootic outbreak came back negative as well. Admittedly, an environmental cause is also possible.
While we've seen HPAI H5N1 avian flu infection in seals before, outbreaks have never been anywhere near this magnitude. After the concerning mink-to-mink transmission event last fall on a mink farm in Spain, there is understandably a lot of interest in this case.
Hopefully we'll get some definitive answers soon.