Florida dolphin dies from ‘mutated’ bird flu that is 18 TIMES more resistant to drug treatment
A bottlenose dolphin in Florida is one of the latest mammals to die from bird flu, according to a new report.
University of Florida scientists found this particular bird flu victim after being notified of a dolphin that appeared to be in distress, but a post-mortem necropsy revealed that it had contracted a highly lethal strain.
The team discovered the virus in the mammal’s brain and lungs, which had mutated and become 18 times more resistant to current drug treatments.
Farmed poultry and wild birds in the US have fallen victim to highly pathogenic bird flu viruses since late 2021, but recently the virus has begun to spread to cows and other mammals.
The dolphin was reported by Florida Fish and Wildlife officials, who saw the animal stuck between a dock and a seawall. By the time a rescue team got there, the young animal had died.
This map shows how bird flu has emerged in a growing number of mammals, which some experts say could mean the flu in the US is moving closer to human spillover
As researchers performed their necropsy of the dolphin, they discovered inflammation in and around the brain and spinal cord.
After the dolphin tested negative for other infections that can cause this type of inflammation, they found bird flu antigen and RNA in its brain and lungs
Specifically, the dolphin was infected with the highly pathogenic bird flu virus A (H5N1) of HA clade 2.3.4.4b.
They found some evidence of the virus in the lungs, but most of it was in the brain and the tissue covering the brain and spinal cord.
This group of avian flu, called 2.3.4.4b A(H5N1), is blamed for killing sea lions in Peru and Chile, as well as harbor seals and gray seals in New England and Canada.
While it is not exactly common for bird flu to kill seals and sea lions, it is not considered rare.
However, bird flu is rare for cetaceans (the group to which dolphins and whales belong).
There has been a recent spread of 2.3.4.4b A(H5N1) among cetaceans, the report’s authors wrote.
Scientists have found evidence of influenza A (H5N1) in the dead bottlenose dolphin: (a) viral antigens in the central nervous system; (b) viral RNA in the same part of the central nervous system; (c) virus antigen in the neurons proper; (d) viral RNA in the same neurons; e) traces of virus in the lungs; and (f) negative screening for viral RNA in the lungs
It is not clear how the bottlenose dolphin in Florida became infected with bird flu. Infections in other marine mammals such as seals and sea lions are somewhat common, but not in dolphins and whales.
It has been found in common dolphins in Peru, Wales and England, in two porpoises in Sweden and England, and in an Atlantic white-sided dolphin in Canada.
These cases are rare, so it is unclear exactly how the bottlenose dolphin became infected in the Florida case.
Shortly before the Florida dolphin died, there was a bird kill in the area that experts linked to HPAI.
However, genetic testing showed that the flu that caused local bird outbreaks did not share the exact genetics with the one that killed the dolphin.
Genetic testing has shown that the virus has not undergone any mutations that would make it more likely to spread to and infect other mammals.
However, researchers found that this dolphin’s specific H5N1 strain showed genetic changes that made it 18 times more resistant to one of the antiviral drugs used to treat bird flu.
Scientists found (a) brain hemorrhages, (b) dead neurons and glial cells in the brain, (c) hemorrhages in the lining of the brain and spinal cord, and (d) minimal changes in lung tissue.
The dolphin in question was first spotted at the end of March 2022, but the case reportpublished in the magazine Communication Biology, only appeared this month.
The team’s report marks the first known case of influenza A in a common bottlenose dolphin, adding to evidence that the virus is spreading among mammals.
Two weeks ago, 18 US states quarantined livestock after reports of bird flu among the animals.
And in New York, several wild bird species have specifically tested positive for H5N1.
It appears that dolphins and whales become infected differently than other animals, with the virus affecting their brains more than their respiratory systems such as the lungs and bronchioles.
“Overall, more research is needed to determine the true susceptibility and route of exposure of influenza viruses in cetaceans,” the scientists behind the new study wrote.
It is possible, they concluded, that some cases have been overlooked because of the unique way the infection manifests in these animals:
‘As cetaceans were previously thought to have low susceptibility to influenza virus infections, this study highlights the importance of routine testing for (highly pathogenic) avian influenza viruses in all mammals and obtaining appropriate samples, including brain, during post-mortem examination.’