A new bird influenza strain – H5N9 – was detected in the County of Merced of California during a commercial duck operation.
According to the World Animal Health Organization – An international consortium of medical professionals, veterinarians and fauna who seek and report animal diseases – Duck tests on the farm showed that animals had been infected with H5N1 and H5N9 strains.
“This case is not unexpected or alarming,” said Annette Jones, veterinarian of the State of California, who said that California Department of Food and Agriculture was “still on alert for any H5 virus”.
The new strain is a combination of the H5N1 strain which has been largely detected around the world and probably a virus of the “weak pathogenic” bird flu – a kind of light virus that moves through birds without killing them, said Henry Niman, an evolving molecular biologist with Recombinomics Inc., a virus and a research company Pittsburgh.
“It's just a new serotype where the N1 segment is replaced by N9,” he said.
Flu viruses are made up of eight segments, including hemagglutinin protein, or a “H” part of the virus, Neuraminidase, or the “N” part. When an animal is infected with two different flu viruses, the genetic equipment of the two can change or recombine to form a new version – which has probably happened here: while hemagglutinin – the part of the virus which allows it to fix a host – has remained the same, a new Neuraminidase – The part that helps to release the virus from infected cells – has been replaced in.
Fortunately, said that Richard Webby of the World Health Organization, the combination that occurred in this population of commercial ducks should not increase the probability of a human pandemic. Webby, director of the WHO Collaboration Center for Flu Ecology Studies in animals and birds, said the virus did not threaten a greater threat to human health than current H5N1 strains circulating in dairy cows, commercial poultry and wild animals.
However, there were genetic restocking between H5N1 and a human seasonal flu, it could be a problem.
Such a combination could provide the bird flu with the equipment it needs to pass more easily and effectively between people.
“We know with certainty this reassortit virus. Nature is a giant Function of function gain,“Said John Korslund, a former USDA scientist, referring to the experiences that researchers have used to make viruses more deadly and transmitted.
Until now, there has been no evidence that one of the strains of the virus of the flipper bird currently circulating in North America has acquired this type of capacity.
According to the centers for disease control and prevention, 67 people in the United States were infected with the H5N1 bird flu. A person is dead. Most cases have been linked to professional exposure – via infected dairy cows or poultry. In three cases, the source remains unidentified.
Niman said there were four bird flu viruses in the H5 family circulating in North America. Two are part of the H5N1 strain. One of them, the H5N1 B3.13 version, was found mainly in dairy and dairy cows. The other H5N1, known as D1.1, largely affected wild birds and commercial poultry. It is also the version of the virus that killed a person in Louisiana and A serious teenager in British Columbia.
Then there is H5N2, which circulates in British Columbia. It is also a restoration of the H5N1 virus with another bird flu virus. It was discovered for the first time in November 2024 and was detected in at least two commercial poultry operations.
And now there is H5N9, which has so far been detected only in the county of Merced, according to the American department of agriculture, which has carried out the tests and the genetic sequencing.
“This is the first confirmed case of HPAI (High Pathogenic Aviaire) H5N9 in poultry in the United States,” the USDA said in a report to the World Organization for Animal Health. “The Inspection Service of the Health of Animals and Plants of the USDA (Aphis), in collaboration with leaders of animal health and fauna, carry out complete epidemiological surveys and increased surveillance in response to events related to HPAI.”
The virus was detected on the duck farm at the end of November. All ducks – approximately 119,000 birds – were euthanized on December 2.
Webby said he thought that the virus had been wiped out in this poultry operation – there was no report appearing in other commercial operations or in wild birds.
So far, no human has been infected with H5N9.
“Bigger: There are several avian flu viruses that are circulating, so it is not horribly surprising,” said Maurice Pitesky, an associate professor who is researching the epidemiology of health and food security in UC Davis. That said, researchers need a more robust surveillance system that provides information on “where aquatic birds are and where we suspect that HPAI is present in wild birds compared to commercial installations”.
Jones, the state veterinarian, said that the Department of Agriculture and USDA “will continue to monitor new or unusual viruses as part of our current test strategy.”
