A new strain of a highly pathogenic bird flu under the name of H7N9 has surfaced on a Mississippi poultry farm where chickens are raised for reproduction.
The discovery of the new strain occurred while the researchers reported separately a potentially positive development: the exhibition to the human seasonal flu can confer a certain immunity to the H5N1 bird flu.
The new strain found in the county of Noxubee, Miss., Was confirmed on March 12 and every 46,000 birds died or were euthanized after the infection, according to the Inspection of animal plant health inspection of the American Department of Agriculture And Mississippi Board of Animal Health. None of the birds have entered the food supply.
The authorities did not say how the birds were infected, although the agents of federal fauna have identified weak pathogenic versions of the H7N9 virus for several years in wild birds. It is possible that the version found in chickens circulates in wild birds, but most researchers think that it has probably acquired its fatal attributes once it has entered the chicken operation Noxubee.
And if this is the case, “my money is on one and to do, perhaps with local spread,” said Richard Webby, an expert in infectious diseases at St. Jude Children's Research Hospital in Memphis, Tenn.
Webby said most epidemics of the bird flu follow this scheme: a weak pathogenic version is introduced into commercial poultry, and it becomes very pathogen once inside.
The introduction of H5N1 – The bird flu virus that infects dairy cows, commercial poultry, pets, wild animals and wild birds since March 2024 – in poultry and cattle populations was a notable exception to this trend: it was already circulating between wild birds and animals as a highly pathogenic virus.
John Korslund, a veterinarian and former USDA researcher, agreed with Webby and noted that the operation hosted chickens: chickens that are cultivated and kept for breeding purposes, not for their meat.
This is important because breeders live for months, even years.
If a weak pathogenic virus “occurs in a flock of flesh, birds do not fall ill and they go to slaughter,” he said. But when a herd of breeder takes up this virus, “the virus can reproduce for weeks. … This may be what happened at Mississippi.”
According to USDA rulesHowever, routine and periodic tests of farmer's birds for low pathogenic avian seamlessness are necessary. In 2017, an epidemic of H7N9 occurred along the Mississippi migration route, probably from the end of February, but only reported in March. A summary report of the epidemic suggested that the virus has been introduced via wild birds.
As suspected in this case, it is believed that it started as a “low path” and has only become “high path” only once he entered the commercial operation.
However, experts said that if they are wrong and that a highly pathogenic virus circulate in wild birds, it will also start to appear in other states and sites.
“Time will say how bad it becomes this time,” Korslund said.
The key to preventing this type of outbreak – or at least get ahead – is monitoring wildlife, experts said.
Agencies such as the USDA, the US Fish and Wildlife Service, the National Wildlife Health Center of the US Geological Survey and the National Oceanic and Atmospheric Administration have divisions which are responsible for sampling of wild birds and other animals for infectious diseases. The information they collect is then used by agriculture and public health officials to determine where and when to strengthen biosecurity, or to keep an eye.
Without this information, said Angela RasmussenVirologist to organize vaccines and infectious diseases from the University of Saskatchewan in Canada, “we are blind”.
In the positive news that has been released this week, An international team Researchers discovered that The ferrets exposed to a current seasonal human flu – H1N1 – before being exposed to H5N1 acquire a certain immunity from the seasonal flu.
The ferrets that were not exposed to the seasonal flu before being infected with the H5N1 had high levels of viruses in their respiratory tissues, as well as a detectable virus in their hearts, their spleen, their liver and their intestine.
On the other hand, those who had been exposed to the seasonal flu beforehand only had virus in the airways – and at fairly low levels.
“The biggest message to take away from our data is that the previous infection on the human seasonal virus can provide a certain level of protection against the letters of the bird flu,” said Seema Lakdawala, microbiologist at Emory University in Atlanta and one of the study researchers.
Webby, St. Jude's researcher, said work supports other research that has examined the potential protection of the exposure to flu.
“It is certainly playing a role in modulating H5N1 disease in humans,” he said, but was probably not the only factor. “After all, many people have severe H1N1 seasonal infections each year despite a lot of immunity to the H1N1 previous exhibition virus.”
But the observation can help to explain why the virus has recently been associated with a generally light disease in infected people. Seventy people in the United States have been infected since March 2024, and A person died. (Four people, including the deceased Louisiana patient, were hospitalized.)
Before last year, the virus would have killed about half of the infected people.
Rasmussen has said that concern is now that if H5N1 is moving to become transmissible between people, it will be young children as well as the former and compromise that are likely to be the most affected. Children under the age of 5 are less likely to have been exposed to seasonal human influenza viruses than children and adults of school age – potentially making them more sensitive to the damage of a virus such as H5N1.
In addition, she said, the viruses of the bird flu circulating in birds and cattle: “As far as we know, cannot easily transmit between people. But, if there is a restocking, then who knows? We do not know what type of residual immunity at the level of the population we would have ”from a virus like this.
The way seasonal flu vaccines could affect this protection is not clear.
“Seasonal vaccines will not provide the same diversity of immune response as natural infection and (are) unlikely to provide the same level of protection,” said Lakdawala, who tests this problem in the laboratory.
