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Bird flu virus was detected in pigs for the first time in the USA

Harry November 1, 2024

The U.S. Department of Agriculture reported Wednesday that the H5N1 bird flu virus was detected in a pig on a farm in Crook County, central Oregon. This is the first case of a pig infected with the current strain of the virus in the United States. Although the sequence of the virus causing this outbreak has not been made public, the Oregon Department of Agriculture (ODA) has informed the media that it is not related to the strain detected among dairy cattle.

Photo of a pig walking through a pasture on a farm near Elliott, Iowa, on December 2, 2021. (AP Photo/Charlie Neibergall)

The animal was euthanized, and an autopsy of the tissue revealed the virus was present throughout the body, according to state veterinarian Ryan Scholz. A total of five pigs and 70 chickens, ducks and geese on the farm were culled as a precaution to prevent further spread of the highly contagious virus. The property is currently under quarantine while surveillance continues. Authorities believe the cause of the outbreak is exposure to infected waterfowl.

Poultry and pigs were housed together. Speaking at the press conference on Wednesday, experts expressed concern especially about the emergence of the virus in pigs; because these animals are susceptible to viruses from both birds and humans. This means viruses can mix with each other and cause mutations, producing a hybrid virus through a process called rearrangement of their genetic structure. Dr., an epidemiologist from Oregon. “We are concerned about changes to this virus,” Dean Sidelinger admitted, but then quickly downplayed the danger, saying, “The risk to the public remains low.”

But scientists I’m talking with ISTAT NewsThose waiting for more details about the investigation were not exactly safe. Flu virologist Dr. of the Icahn School of Medicine at Mount Sinai. “If it doesn’t spread from pigs to pigs and it only happened on that farm, it’s not a big deal,” said Florian Krammer. But he warned: “If it starts spreading from pigs to pigs then it will be a much bigger problem. “I think it would be a disaster if large populations of pigs emerged in the United States, similar to cows.”

The current outbreak of H5N1 avian influenza virus among dairy cattle was first detected in March of this year and has spread to 14 states in 404 dairy herds. Colorado was the epicenter of the outbreak this summer. But this has shifted to California, where 202 cattle herds have been affected, 158 in the last 30 days alone.

The total number of H5N1 cases seen in humans so far has reached 39. 20 of these infections occurred among cattlemen, with 16 workers in California infected. The virus has been detected in 18 poultry workers so far, and nine of them were in Colorado. The Centers for Disease Control and Prevention (CDC) has only tested about 300 people and monitored more than 6,100.

The origin of an H5N1 case in Missouri remains unknown; This is a troubling indication of the potential for human-to-human transmission of the virus. With ever-increasing numbers of infections among farm animals and the people who handle them, concerns about a new H5N1 bird flu outbreak among human populations are beginning to grow.

Adding pigs to the mix further increases the likelihood of a potential pandemic pathogen developing. Dr., an expert on influenza viruses from the Pirbright Institute in Britain. Thomas Peacock said: “Pigs are certainly full of influenza viruses, either seasonal influenza viruses that have occurred in humans in the past or pandemic influenza viruses that have occurred in humans. So they have a really rich genetic material inside them. “That’s the whole idea that pigs are a mixing bowl in that they’re a place where bird and human flu viruses can potentially mix.”

CDCs Emerging Infectious Diseases The magazine, published in April 2024, expressed such concerns on the issue. emergence A case of H5N1 bird flu among pigs warned: “If an avian IAV (Influenza A Virus) strain such as H5Nx 2.3.4.4b successfully infects domestic pigs, it may be transmitted from pig to pig, reassort with endemic swine IAV, or be acquired from birds.” number of adaptive mutations that could enable transmission to mammals could potentially occur (1). Continued circulation and domestic wild mammal infections in the wild bird population increase the risk of exposure to pigs due to the wide distribution of the current epidemic in states with large pig populations.”

Influenza virologist and Director of the World Health Organization’s Collaborating Center for Animal Influenza Ecology Studies, Dr. Richard Webby told STAT News that although H5N1-infected pigs do not readily spread the virus, there are existing strains of H5N1 present. They can infect pigs more easily than previous strains, which “significantly increases the risk from where we are.”

Also, talking with Scientific AmericanWebby theorized that the development of a pandemic virus would require more than a reassortment of circulating strains. “It will require reassortment and then some critical mutations in (a particular) gene.” What Webby means is that such a mutation could allow the virus not only to infect the conjunctiva of the eyes, as currently seen among infected animal workers, but also to adapt to the respiratory system and be transmitted through airborne aerosols.

He added: “The hurdles this virus has to overcome to become a human virus are very high. But anything that gives more opportunities to do so is clearly a cause for concern, whether that’s more human infections from livestock or re-emergence with a seasonal human virus.” “Let there be a potential for coming together, all of these will increase the risk.”

Although current infections with avian influenza virus among agricultural workers have not caused serious illness, recent laboratory studies experiments Isolates of these strains in animal models have led to alarming results.

A study published this week in the journal Nature Dr. The study by Yoshihiro Kawaoka and colleagues from Wisconsin demonstrated that the bird flu virus isolated from the eye of an infected Texas zookeeper spread efficiently in human respiratory cells and was lethal in mice and ferrets. They also showed that the virus spread via aerosol to other animals without any prior adaptation and was lethal to them as well. “Based on these observations, every effort should be made to control outbreaks of HPAI H5N1 (avian influenza virus) in dairy cattle to limit the possibility of further infection in humans,” the researchers warned.

In another recently published study by CDC researchers who used ferrets as an animal model to evaluate the pathogenicity of avian influenza virus, the researchers wrote:

In this study, we used the ferret model, a well-characterized strain that allows simultaneous investigation of viral pathogenicity and infectivity, in the evaluation of the A/Texas/37/2024 (TX/37) A(H5N1) virus isolated from a dairy farm. Worker in Texas.

Here, we show that the virus has a remarkable ability for robust systemic infection in ferrets, resulting in high levels of virus shedding and dissemination to naive contacts. Ferrets inoculated with TX/37 exhibited a severe and fatal infection characterized by rapid viremia and extrapulmonary dissemination. The virus was transmitted efficiently in a direct contact environment and was capable of indirect transmission through fomites. Airborne transmission was supported by the detection of infectious virus shed into the air by infected animals, although at lower levels compared to the highly transmissible human seasonal and swine H1 subtype strains.

Our results show that, despite retaining bird-like receptor binding specificity, TX/37 showed higher virulence, infectivity, and airborne transmission compared to other clade 2.3.4.4b virus isolated before the 2024 cattle outbreaks; This underscores the need to maintain public health vigilance.

These worrying developments need to be widely discussed and shared among agricultural workers and more generally. Public health should not be reduced to scientific conferences and publications in journals, nor should it be excluded from reporting. These consequences require action by local and federal governments to prevent the development of the next epidemic. The wait-and-see approach is foolish and has potentially fatal global consequences.

Semainede4jours

Semainede4jours

Bird flu virus was detected in pigs for the first time in the USA

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