Over the past year, the United States has faced the worst bird flu outbreak in history, affecting at least 47 states. According to statistics from the US Department of Agriculture, at the end of last year, more than 58 million poultry birds are infected and will have died or been culled in 2022, surpassing the annual figure of about 50.5 million in 2015 historical record.
An outbreak of bird flu has decimated poultry populations across the United States. For example, laying hens accounted for more than 70% (about 43 million) of poultry deaths due to the epidemic last year. This phenomenon has caused a sudden increase in the price of eggs, and taking California as an example, the price of a dozen eggs was as high as US$7.37 (about NT$222) in early January, three times more than the previous year. Although the price of eggs in the United States has fallen significantly in the past month, the impact of the bird flu epidemic may be much greater than that.
The issue of climate change is urgent! More than 50% of infectious diseases are exacerbated by extreme weather (gene international version online)
An unprecedented global outbreak
Bird flu (mainly H5N1) has also broken records of large-scale outbreaks in many parts of the world in the past year. According to the European Food Safety Authority, a total of 2,520 poultry cases were recorded across Europe between October 2021 and September 2022, spreading across 37 countries and killing or culling more than 50 million birds. As for Asia, the total number of birds killed or culled due to bird flu in Japan will break the record of 10 million in 2022, and the epidemic will affect 23 hypotheses. In addition, taking the currently circulating H5N1 as an example, it is one of the few types of virus that can infect humans. Some experts worry that as the virus gene continues to mutate, it will not only increase the chance of birds spreading each other, causing a larger outbreak, but also more likely to mix with human flu viruses , increasing the human-to-human risk. transfer.
Facts about bird flu
Bird Flu is caused by Type A which mainly affects birds and poultryfluCaused by the Influenza A virusinfectious disease, it can be spread through the digestive tract, respiratory secretions, skin wounds and conjunctiva. In addition to bird-to-bird transmission, people and other animals can become infected if they come into contact with the blood, faeces or secretions of infected birds (or contaminated items), or if they breathe air that contains virus particles.
According to the pathogenicity and lethality of the virus, avian influenza can be divided into at least two categories: highly pathogenic avian influenza (HPAI) and low pathogenic avian influenza (LPAI). In addition, scientists will also divide viruses into different subtypes (Subtypes) based on the combination of virus surface proteins Hemagglutinin and Neuraminidase. As well as the currently circulating H5N1, other examples include the equally pathogenic H5N8, which has caused bird flu outbreaks in several countries in Europe and Asia since 2020, and H7N9, which has caused hundreds of cases in China in 2013 and 2014 Cases of human infection.
H5N1 bird flu is of concern in part because the virus is highly contagious and affected birds are already contagious before becoming ill. On the other hand, the virus is also quite fatal to humans. According to the World Health Organization (on January 27), there were only 868 cases of human infection with H5N1 in the last 20 years, but 457 of them were killed, the mortality rate was as high as 53%.
Spanish mink together infected with the epidemic, a human pandemic is imminent?
Avian influenza viruses can generate new viruses with greater transmissibility, faster growth and stronger pathogenicity through gene mutation and gene reassortment. For example, when a host is infected with bird flu and human influenza A viruses, gene reassortment can occur. In this process, the genetic material of the two viruses is mixed and rearranged to form new gene segments that give the virus the characteristics of the original strain with these new genes (such as the ability to infect humans ). Many scientists worry that the bird flu virus will one day evolve to spread among humans through droplets (sneezing or coughing), triggering a global pandemic that could kill millions of people.
Climate change is also a cause for concern. On the one hand, global warming shortens the time for the virus to grow in the host, and also makes more places suitable for the virus to survive. On the other hand, migratory birds often carry different types of bird flu viruses, and climate change will change the migration patterns of migratory birds, increasing the risk of the virus spreading to new areas.
According to the Centers for Disease Control and Prevention (CDC), there have been sporadic cases of H5N1 bird flu infection in mammals in many parts of the world in the past, including pigs, cats, dogs, tigers and Leopards and more. But in October last year, a large number of mink died of pneumonia in a mink farm in Galicia, in north-west Spain. Vets initially suspected that the pathogen was the new coronavirus, but later genetic sequencing results confirmed that the sick mink was infected with H5N1. As a result, the remaining 52,000 mink in the field were all culled, and the workers in the field were also required to be quarantined and take antiviral drugs. Fortunately, no one was infected in the end. The incident has raised alarm bells, raising concerns that the bird flu virus may have evolved to spread widely among mammals, further increasing the risk of a human pandemic.
World Health OrganizationDirector-General Tedros Adhanom Ghebreyesus recently urged countries to closely monitor mammals for bird flu in a virtual press conference on global health issues. While the risk of the virus infecting humans remains low, attendees warned: “We cannot assume that this will always be the case and must be prepared for any change in the status quo.”
In addition to the possibility that natural evolution could make the virus stronger, some people in the scientific community worry that the research on the bird flu virus could intentionally or unintentionally create a highly lethal “super H5N1” and can human-to-human. transfer. As early as 2011, scientists had created an H5N1 virus strain that could be easily transmitted among ferrets, meaning that it is no longer impossible to artificially create a virus strain that can transmit from person to human. Once the research data falls into the wrong hands, or the virus is accidentally released from the laboratory, the results will be disastrous. In view of this, at the end of 2011, the National Science Advisory Board for Biosafety (NSABB) asked the two academic journals “Nature” and “Science” to review sensitive details in related papers and avoid revealing research methods AND experimental details, to prevent technical knowledge from being used by terrorists to develop biological and chemical weapons.
How should we respond?
If humans are infected with bird flu, they will usually receive supportive treatment based on symptoms. In severe cases, ventilators may be needed to assist breathing. According to the CDC, some antiviral drugs such as Oseltamivir, Peramivir, and Zanamivir are also currently used to treat bird flu. To prevent the spread of bird flu, people should avoid direct contact with wild birds. In contact with birds or their droppings, wash your hands thoroughly with soap immediately; chicken, eggs and other foods should be cooked and eaten; if you find dead birds suspected of being infected with the disease, you should report to the authorities as In addition, it is also recommended to vaccinate every year with a flu vaccine. Bird owners and poultry operators should wear protective equipment such as gloves and N95 masks when touching birds, avoid touching the nose, mouth and eyes after contact, and should wash their hands thoroughly; in addition, they should change clothes before touching any birds.
Further reading: World’s first human infection with H10N3 bird flu! How does the virus spread between humans and animals?
Addresses:
1. https://www.aphis.usda.gov/aphis/ourfocus/animalhealth/animal-disease-information/avian/avian-influenza/hpai-2022/2022-hpai-commercial-backyard-flocks
2. https://www.latimes.com/california/story/2023-01-07/7-a-dozen-why-california-eggs-are-so-expensive-and-increasingly-hard-to-find
3. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2023.7786
4. https://www.nippon.com/en/japan-data/h01560/
5. https://apps.who.int/iris/handle/10665/365675
6. https://www.cdc.gov/flu/avianflu/virus-transmission.htm
7. https://www.cdc.gov/flu/avianflu/h5n1-animals.htm
8. https://www.science.org/content/article/incredibly-concerning-bird-flu-outbreak-spanish-mink-farm-triggers-pandemic-fears
9. https://www.who.int/publications/m/item/virtual-press-conference-on-global-health-issues-transcript—8-february-2023
10. https://www.nih.gov/news-events/news-releases/press-statement-nsabb-review-h5n1-research
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