GENERICO.ruScienceThe cause of the mass death of seals has been named: the infection threatens the fragile Antarctic ecosystem

The cause of the mass death of seals has been named: the infection threatens the fragile Antarctic ecosystem

“The number of dead animals is much higher than what we see”

The mass death of seals in the hot Atlantic received an explanation: bird flu was to blame. Scientists warn further spread of the deadly disease could threaten fragile ecosystems as tests show seals were killed by H5N1 on South Georgia Island.

A British team of virologists has confirmed the first cases of avian flu in elephants and fur seals in the sub-Antarctic region, as the highly contagious H5N1 virus continues to spread around the world, writes The Guardian.

Researchers previously reported mass mortality of seals and that a number of elephant seals on South Georgia Island – British Overseas Territory in the South Atlantic Ocean – showed symptoms of bird flu. But while cases of the disease in seabirds have been confirmed, infections in seals have been classified as suspicious, pending laboratory results.

The first known cases of H5N1 were discovered in the Antarctic region in October among a brown skua on Bird Island, nearby from South Georgia. Two months later, hundreds of elephant seals were found dead. Also in several other places, deaths of fur seals, kelp gulls and brown skua have increased.

Marco Falchieri, a scientist with the Animal and Plant Health Agency's (APHA) Avian Influenza and Virology Group, which collected samples in south Georgia that tested positive for avian influenza. He said he saw about 20 dead elephant seals. “It's almost heartbreaking, emotionally, to see so many seals dead.”

Other seals were showing respiratory signs of bird flu, he said, citing “coughing, sneezing, discharge from the eyes, nose, slow rocking.” head and tremor”.

Falchieri says the death toll in southern Georgia was likely about 100 animals, mostly elephant seals, which appear to have suffered more than fur seals.

“My biggest concern is adaptive mutation in mammals that we don't see in these new samples, but we need to continue monitoring,” the scientist said. The adaptive mutation, he added, “could mean that this is becoming a mammal-adapted virus and therefore increases the risk to humans as well.”

The spread to mammals in south Georgia is “a reflection of what is happening all over the world,” says Ashley Banyard, APHA virologist. The team of scientists diagnosed samples brought from the island in mid-December.

According to the virologist, side effects occur “when too many birds get avian flu and mammals come into close contact with the droppings of sick birds or when mammals eat the carcass of an infected bird.”

A polar bear was confirmed dead in December from bird flu in Alaska, and an estimated 20,000 sea lions have died from the virus in Chile and Peru, The Guardian reports.

While the deaths of subantarctic seals and birds are concerning, Banyard says the good news is that the virus has not yet spread to other species. “Two years ago we were worried that penguins might become infected and die from this disease in the region, but this did not happen, so this is almost a positive result.”

However, according to a virologist, if the bird As influenza continues to spread throughout the sub-Antarctic region, it “could significantly threaten fragile ecosystems and potentially put a number of very large populations of seabirds and mammals at risk.”

Norman Ratcliffe, a seabird ecologist with the British Antarctic Survey, says that about 98% of the world's fur seal population was found in southern Georgia, and that the region contained “globally important populations of elephants and fur seals, and these populations are now in danger of significant decline.”

Ratcliffe argues that there is no way to know the total number of seals killed, either from deaths at sea or from the carcasses being fished out, “but we do know that the death toll is much higher than what we see , – and mortality is much higher than usual for this time of year”.

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