New research shows that bird flu doesn’t just lurk in cows. Florida scientists have reported the first known case of highly pathogenic avian influenza H5N1 in a bottlenose dolphin (Tursiops cut off). Although the case dates back to 2022, it is the latest indication that these flu strains may be able to infect a wide range of mammals.
The report was published Friday in nature diary communication biology. According to the newspaper, the flu-infected dolphin was first identified on March 29, 2022. Researchers at the University of Florida’s Marine Animal Rescue Program were notified of a dolphin that appeared to be in distress near Horseshoe Beach in North Florida. However, when they arrived, the dolphin had already died. It was then packed in ice and taken to the university for an autopsy the next day.
The necropsy revealed clear signs of poor health and inflammation in the dolphin’s brain and meninges (the membrane layers that protect the brain and spinal cord). The dolphin tested negative for other common infectious causes of encephalitis, prompting the researchers to expand their search. Knowing that wild birds can develop neuroinflammation from highly pathogenic strains of avian influenza, that there had been several recent bird deaths linked to influenza in the area, and that there had been recent outbreaks elsewhere in other marine mammal populations, they decided them to look for it. Tests then revealed the presence of H5N1 in the dolphin’s lungs and brain.
There were Sightings Recently, other marine mammals, such as seals and other dolphin species, have also become ill with highly pathogenic avian influenza (HPAI). However, this is the first reported case in a bottlenose dolphin and the first report in a cetacean (dolphin and cetacean) in North American waters.
Avian influenza strains are classified as highly pathogenic if they cause severe illness and death in wild birds. So it’s not necessarily certain that they are just as dangerous to other animals that they infect. The current outbreaks of H5N1 bird flu in cowsSo far, for example, the illnesses have mostly been mild. But strains belonging to this particular lineage of H5N1 (2.3.4.4b) have been deadly to marine mammals.
The strain in this case did not appear to develop known genetic changes that would facilitate infection and transmission between mammals, the authors noted. But flu viruses mutate very quickly, leaving open the possibility that some strains will adapt and adopt the right changes that can make them a much greater threat to mammals both on land and in the sea.
“Aside from the risk to human health, the consequences of adapting A(H5N1) viruses to increased replication and transmission between dolphins and other cetaceans could be catastrophic for these populations,” the authors write.
Researchers are continuing to investigate the case and hope to determine the origin of the dolphin infection and better understand the potential of avian influenza strains to successfully cross the species barrier to these marine mammals.
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