“An unusual mortality” among gray seals and harbor seals in the world’s largest estuary, the St. Lawrence River in Quebec, Canada, was described by American CDC researchers in the journal ‘Emerging Infectious Diseases’. The event dates back to 2022 and analyzes have shown that for 15 specimens subjected to autopsy the cause of death was an infection with the highly pathogenic avian H5N1 virus (Hpai H5N1), the one that is causing alarm in the world due to the epidemic which affected dairy cattle in several US states. Its RNA was also detected in 6 swabbed seal carcasses. The virus was successfully isolated in 16 cases out of 21 total, and in 11 of these 16 signs of genetic reassortment between Eurasian and North American lineages were highlighted.
“The infection of mammalian species such as seals by the Hpai H5N1 virus raises concern about recent mutations that make it possible for the ‘avian’ virus to enter and replicate within mammalian cells,” warn the authors of the study. “From the point of view of human health – they underline – these changes in the range” of possible “viral hosts justify continuous vigilance to identify a potentially deadly epidemic before its appearance. Marine mammals, such as seals or other pinnipeds – is the fear of scientists – could act as reservoirs for this virus”, an eventuality that “could contribute to increasing the risk of mutations and viral reassortment, favoring the infection of new mammalian hosts” until reaching humans more permanently.
“Therefore – the researchers conclude – monitoring the presence and molecular characteristics of the Hpai H5N1 virus in wild marine mammal populations is essential”, also as an assessment of the “public health risk associated with this emerging pathogen-host dynamic”.
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