by In February 2024 there were state veterinarians in the Czech Republic, which examined an outbreak of bird flu, in the middle of a confusing case.
The highly pathogenic H5N1 virus devastated a herd of chickens on a highly safe farm, the home of a breeding program that produced hybrid birds with specially colored feathers and eggs. His chickens were also infected in a nearby facility of the same company.
How had the virus come in? The facilities were up to date with the latest art. The water on the chicken farms was filtered and supplied by their own fountain. The chicken houses had huge fans caused by the barns. The furnishings were surrounded by stable, well -maintained fence, which kept wild animals away. The employees were not even allowed to keep their own chickens at home.
Her investigation led the researchers to the conclusion that this special case included a number of “exactly correct” conditions that made it possible for the virus to blow the wind onto the chicken farm.
It is believed that wild birds that carry the flu viruses in their intestines and pour them into their feces, the main method for H5N1 was inserted on the farms. However, experts say that the windborne spread of bird flu was previously suspected.
“The whole idea of being a kind of wind has been out there for some time,” said Dr. Richard Webby, who heads the collaboration of the World Health Organization for Studies on the Ecology of Influenza in animals.
“It is incredibly difficult to actually measure,” he said, “to receive the final data to say yes or no.”
Webby was not involved in the new study, but said that he was in contact with a veterinarian in California, who believes that wind played a role in the recent spread of H5N1 between a few herds of cattle in Central Valley.
But even if it moves through the air, he said that the bird flu does not necessarily make a greater threat to people.
On the one hand, the current versions of the H5N1 virus that infect animals do not seem to infect people very well. The more the virus spreads, the more possibilities its craft have to improve and better break into human cells, but at the moment there is no sign that it has made this leap to be a completely human pathogen.
On the other hand, you only need a small amount of virus to make a bird sick, and it would probably need a lot more to infect a person. Particles, even viruses, disperse in air, which means that a virus in the wind is probably only available in very small quantities.
How the virus jumped between farms
In the case of the chicken farm in the Czech Republic, the scientists only came to the origins of the outbreak from a nearby duck farm, which had also torn the bird flu through their herds a week earlier.
The duck farm with 50,000 birds was completely different from the chicken system. It was near a lake where wild ducks took place. The ducks of agriculture were kept in buildings with natural ventilation and a fundamental level of organic safety – the precautionary measures taken to protect animals on a farm.
The course of the infection on the duck farm looked very different than with the chickens.
The bird flu swept like a running fire through the duck houses. On February 4, the first day of the outbreak, 800 ducks died. 5,000 had died within two days. On February 7 and 9, the entire herd was depopulated to control the spread of the infection and prevent greater suffering for the birds.
The chickens in the breeding ground were also different in other ways: they slowly got sick. Over a week, they gradually stopped eating and drinking, and the farm owners noticed that some birds died, mostly near the barns of the barns.
Finally, the infection spread on both barns in the breeding system and another barn at the second location. Thousands of birds were lost, including critical breeding stocks.
The government’s veterinary researchers collected samples of the viruses that had infected the ducks, the chickens in the breeding ground and chickens on the second farm to see what they could learn.
Three H5N1 trunks sequenced by the duck farm were genetically identical to tribes that were found in the birds that first got sick on each farm, which indicates that the duck farm had been the source of the chicken outbreak.
But how? The duck farm was almost 5 miles west of the chicken systems, and the investigators could not find any physical connections between the two. None of the people who worked on the duck farm ever went to the chicken farms; Even the contractors who have deducted or came to collect waste were different. The investigators said they had excluded any human connections between the farms.
There was no heavy water bodies near the chicken farm, which they distract from the idea that wild birds may have worn the flu virus.
The weather gives an idea
Then the researchers checked the weather patterns for the week when the chickens got sick. There had been a steady breeze from the West. There was an extensive cloud cover that would have blocked the germinal UV light from the sun. The temperature was cool, but not frozen, between 40 and 50 degrees, and viruses love cold air.
In other words, perfect conditions, to transport a virus and survive a long journey.
Dr. Kamil Sedlak, who heads the state veterinary institute in Prague and is a senior author of the study, says that the Windborne spread in this case was the best fit after examining all options.
“I think that under certain conditions the spread of the Vogel -Influenzavirus can occur through wind,” he said.
The Czech researchers published their study as a form before the peer review.
Webby said that the virus particles could have had a ride with a slightly larger one, like Dander from the ducks, and that allowed them to travel so far.
The authors of the study did not try to try the air near the duck or chicken farms for viruses, and they find that earlier air sample studies in and around pigs and poultry houses have found a high degree of influenza viruses with bird observations. However, the concentrations of the virus quickly dissolved when air flooded away from barns.
That may be the reason why the chickens got slower: they got a lower dose of the virus from very low values in the air. The fact that the first chickens to die were near the ventilation opening openings was another indication.
“I think that you are doing a convincing case based on the knowledge of the farms,” said Dr. Montse Torremorell, professor and chairman of the veterinary population medicine at the University of Minnesota, which was not involved in the new study.
In 2015, Torremorell carried out air samples around poultry rods in the United States during the last major outbreak of Vogel Influenza. It found a high degree of infectious virus that flowed out in poultry houses from the large exhaust fans.
It’s not just about how much virus blows into the air, she said, but also where it ends up. These springs of infectious aerosols can land on clothing, equipment and vehicles that the virus can also carry from one place to the next.
Layered protection approaches
Torremorell said that the spread of air farmers should be something if they think about opportunities to protect their cattle and herds.
“I think the air transmission should be on the table,” she said.
But it is difficult to defend yourself because people hear “spread out in the air” and feel powerless to stop the virus.
“People often say: ‘Oh, it’s in the wind. I can’t do anything about it. “Then stop doing the basic biosecurity that it is also very important that you have to do it,” she said.
However, she says that she forgot the lessons from the Covid 19 pandemic, as the spread of a virus requires layered protection approaches. Current precautions such as the restriction of access to farms and wearing personal protective equipment should be kept in place, but filtering the air in barns could also help protect animals and agricultural workers from bird flu.
Dr. Michael Osterholm, who heads the Center for Infectious Disease Research and Policy at the University of Minnesota, believes that the spread of Windborne now plays a role in the H5N1 transmission.
“I think there are more wind -driven H5N1 in the community at the moment because the number of water birds is infected,” he said.
Water birds such as ducks and daisies in lakes, he says, and the wind that blows over this water can lead to the virus to nearby farms.
“We are currently in an unprecedented area,” said Osterholm. “It’s all over the country.”
Osterholm believes that the spread in the air or in the windborne could blame some infections in which a source of the virus – like contact with a sick animal – could not be identified. The latest case of the three veterinarians who have tested positively for antibodies against the H5N1 virus at a conference. Two of the three had no known exposure to sick animals.
“I think it is a very low risk that people with such a virus will be infected, but I think it happens,” he said.
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