Materiały źródłowe

• #1 Avian Influenza in Birds: Causes and How It Spreads | Bird Flu | CDC

  https://www.cdc.gov/bird-flu/virus-transmission/avian-in-birds.html

  Avian influenza refers to disease in birds caused by infection with avian (bird) influenza (flu) Type A viruses. […] Avian influenza A viruses have been isolated from more than 100 different species of wild birds around the world. These viruses occur naturally among wild aquatic birds worldwide and can infect domestic poultry and other bird and animal species. […] Wild aquatic birds, especially dabbling ducks, are considered reservoirs (hosts) for avian influenza A viruses. […] Avian influenza A viruses are very contagious among birds, and some of these viruses can sicken and even kill certain domesticated bird species, including chickens, ducks and turkeys. […] Infected birds can shed avian influenza A viruses in their saliva, nasal secretions, and feces. […] Avian influenza A viruses are classified into the following two categories: low pathogenicity avian influenza (LPAI) A viruses, and highly pathogenic avian influenza (HPAI) A viruses.

• #1 Avian Influenza (Bird Flu): Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/2500029-overview

  Avian influenza, commonly referred to as bird flu, describes a group of viral infections primarily affecting birds, particularly domestic poultry. However, the term can be misleading, as it encompasses zoonotic infections in humans caused by strains of the influenza A virus. Influenza A is an orthomyxovirus characterized by a segmented RNA genome, which allows for genetic reassortment and antigenic shifts. These characteristics make avian influenza a potential and unpredictable threat to human health. […] Among these, influenza A is the most significant in terms of zoonotic potential and pandemic risk. The influenza A virus is further categorized into various subtypes based on two surface proteins: hemagglutinin (H) and neuraminidase (N). There are 16 known H subtypes and 9 N subtypes, leading to a variety of combinations, such as H5N1 and H7N9. Historically, strains like H5N1 have posed significant threats to human health due to their high mortality rates and potential for transmission.

• #1 Avian Influenza in Poultry and Wild Birds – Poultry – Merck Veterinary Manual

  https://www.merckvetmanual.com/poultry/avian-influenza-in-poultry-and-wild-birds/avian-influenza-in-poultry-and-wild-birds

  Avian influenza viruses are type A orthomyxoviruses characterized by antigenically homologous nucleoprotein and matrix protein, which are identified by serological testing such as agar gel immunodiffusion (AGID) or ELISA. AI viruses are further divided into 16 hemagglutinin (H1H16) and 9 neuraminidase (N1N9) subtypes. […] High-pathogenicity avian influenza (HPAI) viruses arise from the mutation of some H5 and H7 LPAI viruses. […] The morbidity and mortality rates of LPAI viral infections are usually low, unless the infection is accompanied by secondary bacterial or viral infections or aggravated by environmental stressors. […] Most human cases have originated from infection with H5 Gs/GD lineage HPAI viruses and H7N9 LPAI and HPAI viruses (Eurasian lineage). […] The H5N6 Gs/GD lineage HPAI virus has caused 90 laboratory-confirmed cases of infection in humans in China and Laos, with 35 deaths.

• #1 Avian Influenza – WOAH – World Organisation for Animal Health

  https://www.woah.org/en/disease/avian-influenza/

  Avian influenza, also known as bird flu, is a highly contagious viral disease that affects both domestic and wild birds. This complex disease is caused by viruses divided into multiple subtypes (i.e. H5N1, H5N3, H5N8 etc.) whose genetic characteristics rapidly evolve. […] The many strains of avian influenza viruses can generally be classified into two categories according to the severity of the disease in poultry: low pathogenicity avian influenza (LPAI) that typically causes little or no clinical signs; high pathogenicity avian influenza (HPAI) that can cause severe clinical signs and possible high mortality rates. […] While it is likely that international trade, farming practices and migratory wild birds have contributed to the spread of avian influenza, the current wide range of avian influenza subtypes circulating shows an ever-evolving complexity in both virus genetics and spatiotemporal distribution. This might be explained by multiple reassortments with low pathogenicity viruses circulating in wild birds. […] The transmission of avian influenza from birds to humans is rare and usually occurs when there is close contact with infected birds or heavily contaminated environments. […] The risk of transmission of avian influenza from a sick cat to a human is currently very low or negligible.

• #1 Avian Influenza in Birds: Causes and How It Spreads | Bird Flu | CDC

  https://www.cdc.gov/bird-flu/virus-transmission/avian-in-birds.html

  Highly pathogenic avian influenza viruses cause severe disease and high mortality in infected poultry. […] HPAI A(H5) or A(H7) virus infections can cause disease that affects multiple internal organs with mortality up to 90% to 100% in chickens, often within 48 hours. […] Both HPAI and LPAI viruses can spread rapidly through poultry flocks. […] Domesticated birds (chickens, turkeys, ducks, etc.) may become infected with avian influenza A viruses through direct contact with infected waterfowl or other infected poultry, or through contact with surfaces that have been contaminated with the viruses. […] The potential for low pathogenic avian influenza A(H5) and A(H7) viruses to evolve into highly pathogenic avian influenza A(H5) and A(H7) viruses with major agricultural implications. […] The possibility that avian influenza A viruses could be transmitted to humans exposed to infected birds.

• #1 Avian Influenza – Infectious Diseases – MSD Manual Professional Edition

  https://www.msdmanuals.com/professional/infectious-diseases/respiratory-viruses/avian-influenza

  Avian influenza is caused by strains of influenza virus A that normally infect only wild birds and domestic poultry. Infections due to some of these strains have been detected in humans. […] Most subtypes of avian influenza that have caused human infections are H5, H7, and H9 viruses. Most cases of avian influenza in humans have been caused by Asian strains H5N1 and H7N9, but other types have also caused some human infections. […] Humans can become infected with avian influenza viruses through inhalation of or direct contact with secretions (saliva, mucous, or feces) from infected birds. It is likely that avian influenza viruses of any antigenic specificity can cause influenza in humans whenever the virus acquires mutations, enabling it to attach to human-specific receptor sites in the respiratory tract.

• #1 Avian Influenza (Bird Flu) Fact Sheet | Cornell University College of Veterinary Medicine

  https://www.vet.cornell.edu/highly-pathogenic-avian-influenza-bird-flu-resource-center/avian-influenza-bird-flu-fact-sheet

  Like all viruses, influenza viruses can change over time. Every time an animal or person is infected, small changes in the genetic sequence of the virus occur, and these help the virus avoid getting cleared by the immune system. […] Large genetic changes can also occur when one individual is infected with more than one type of influenza virus and the viruses mix their genetic material. This can result in new forms of the virus that suddenly gain the ability to infect new species. […] Avian influenza can be transmitted in three ways: Direct contact, Indirect contact (e.g. contaminated surfaces), Inhalation. […] Infected birds (whether showing symptoms or not) can shed the virus in saliva, ocular, nasal or oral secretions, and feces. […] The consumption of raw foods, including raw milk and raw milk products, poses known risks of transmission and should be avoided by domestic cats and people.

• #1 Facts about avian influenza – inspection.canada.ca

  http://inspection.canada.ca/en/animal-health/terrestrial-animals/diseases/reportable/avian-influenza/facts-about-avian-influenza

  Avian influenza viruses, such as the highly pathogenic H5N1 virus present in Asia, can, on rare occasions, cause disease in humans. […] Transmission to humans has occurred when people have had close contact with infected birds or heavily contaminated environments. […] Wild birds, especially waterfowl, are natural reservoirs of influenza viruses. They are not normally affected by the disease, but can still transmit it to domestic birds. […] The disease can spread to birds through contact with infected poultry and poultry products. It can also spread through contaminated manure, litter, clothing, footwear, vehicles, equipment, feed and water. […] There is no treatment for birds that have the disease. […] Vaccinating the birds may play a role in reducing the spread of the disease but does not eliminate the virus.

• #1 Avian Influenza (Bird Flu) Information for Information for People Who Handle Poultry

  https://www.health.ny.gov/diseases/communicable/influenza/avian/poultry_handlers.htm

  Highly pathogenic avian influenza (bird flu) causes severe disease and death in poultry including chickens, geese, ducks, and turkeys. […] People can get avian influenza from poultry by: Breathing in droplets or dust contaminated with the virus, particularly in heavily contaminated environments like coops or barns. […] If birds in your flock have suspected or confirmed avian influenza: Do not touch the sick or dead birds without wearing personal protective equipment (PPE).

• #1 Bird Flu H5N1 Causes, Symptoms and Treatments | Froedtert & MCW

  https://www.froedtert.com/infectious-diseases/bird-flu

  Bird flu, also known as avian influenza, is an infectious disease caused by a virus that mainly affects birds but can also infect humans. The disease comes from influenza A viruses, which have several subtypes. The subtypes fall into categories based on the protein composition on the virus’s surface, namely, hemagglutinin (H) and neuraminidase (N) as seen in names such as H5N1 and H7N9. […] Bird flu refers to a specific Type A flu virus, H5N1, which currently spreads easily among birds, but can sometimes spread to other animals and humans. […] The virus can survive in the environment especially in water and on surfaces for long periods. […] Migratory birds play a significant role in spreading the virus during seasonal migration, introducing it to areas that have not been affected by the virus before. […] Research is ongoing to develop vaccines for humans that can offer a stronger defense against bird flu. Developing a vaccine is challenging due to the virus’s ability to change, requiring constant updates to vaccine formulations.

• #1 Avian Influenza (Bird Flu) Fact Sheet | Cornell University College of Veterinary Medicine

  https://www.vet.cornell.edu/highly-pathogenic-avian-influenza-bird-flu-resource-center/avian-influenza-bird-flu-fact-sheet

  Avian influenza is an influenza type A virus that occurs naturally in wild aquatic birds, including ducks, geese and gulls. Mild forms of avian influenza (known as low pathogenic avian influenza, or LPAI) are routinely found in wild birds and dont cause serious illness. […] From time to time, a mild strain changes through mutation or mixing with other flu viruses into a more severe type of the virus (highly pathogenic avian influenza, or HPAI). HPAI historically has caused 75-100% mortality in poultry, like chickens and turkeys, as well as some wild birds. […] The current outbreak of HPAI has spread into dairy cattle, domestic cats, many species of wildlife and also a small number of people. […] The current outbreak in North America began in Nov. 2021, when the virus was introduced either via trans-Atlantic migration or transmission of the virus in Iceland or Greenland from Europe, where it had already been circulating for several years.

• #1 Pathology, Molecular Biology, and Pathogenesis of Avian Influenza A (H5N1) Infection in Humans

  https://pmc.ncbi.nlm.nih.gov/articles/PMC2329826/

  Various factors are thought to be involved in the pathogenesis of H5N1 influenza, and a combination of these factors most likely determines the extent of tissue injury and disease outcome. […] The role of dysregulation of cytokines and chemokines has been studied extensively and may be one of the key mechanisms in the pathogenesis of H5N1 influenza, in addition to injury resulting from viral replication. […] Up-regulation of functional TRAIL in macrophages infected with the H5N1 virus may be another important factor in the pathogenesis of H5N1 influenza virus infection. […] H5N1 viral replication appears to be prolonged with high levels of viral RNA, and the virus may disseminate to extra-pulmonary organs. […] The NS gene of H5N1 viruses may also account for up-regulation of cytokines and chemokines. […] The presence of glutamic acid at position 92 of NS1 appeared to be a prerequisite for the resistance to antiviral cytokines. […] In fact virulence appears to be a polygenic trait with several genes co-operating together.

• #1 Pathology, Molecular Biology, and Pathogenesis of Avian Influenza A (H5N1) Infection in Humans

  https://pmc.ncbi.nlm.nih.gov/articles/PMC2329826/

  H5N1 avian influenza is a highly fatal infectious disease that could cause a potentially devastating pandemic if the H5N1 virus mutates into a form that spreads efficiently among humans. […] Dysregulation of cytokines and chemokines is likely to be one of the key mechanisms in the pathogenesis of H5N1 influenza. […] H5N1 influenza is still a relatively novel disease with poorly understood pathology and pathogenesis. […] The major pathogenetic mechanisms and etiological factors of H5N1 influenza are discussed. […] The various molecular determinants of increased pathogenicity of H5N1 avian influenza viruses that have been identified in recent years are also presented. […] H5N1 influenza appears to be a systemic infection in both human and animal cases. […] It appears that the virus may also spread to other organs, such as the kidneys and liver, as has also been demonstrated in animals.

• #1 Avian Influenza (Bird Flu): Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/2500029-overview

  The spillover of avian influenza into other species is facilitated by several factors: […] Genetic Reassortment: The segmented nature of the influenza A virus genome allows for genetic reassortment when a host is co-infected with multiple strains. This can result in the creation of new viral strains with altered antigenic properties, potentially evading the immune response of existing hosts. […] Host Susceptibility: Certain strains of avian influenza have shown a preference for specific receptors found in different species. For example, the receptor usage of the virus can determine its ability to infect mammals. The presence of sialic acid receptors, which bind to hemagglutinin, plays a crucial role in the virus’s ability to infect various hosts. […] Recent findings have highlighted the ongoing threat of avian influenza, particularly the H5N1 strain, to both animal and human health:

• #1 What makes the bird flu virus so unusual? – News Bureau

  https://news.illinois.edu/what-makes-the-bird-flu-virus-so-unusual/

  In cats and many wild carnivorous mammals, H5N1 causes neurological disease rather than respiratory illness because their birdlike SA receptors are located in the brain. […] Humans do have some birdlike receptors, but they are deep in the lungs. This makes human infection extremely rare. However, when it does occur, the disease is severe because the virus must reach deep lung tissue to replicate effectively. […] Despite widespread human exposure particularly in China, where data collection is strong only a handful of infections have occurred. This suggests H5N1 is not well-adapted for human-to-human transmission. […] At this stage, H5N1 is primarily a livestock issue. While concerns about human transmission persist, the reality is that this virus is 98% a domestic livestock story and 12% a domestic cat story. Right now, its more of a food supply issue than a human health crisis.

• #1

  https://www.ncid.sg/Health-Professionals/Diseases-and-Conditions/Pages/Avian-Influenza.aspx

  Caused by type A strain of influenza. Two types of avian influenza are defined based on their virulence: a highly virulent type that causes fowl plague (highly pathogenic avian influenza, HPAI) and an avirulent type that causes only mild or asymptomatic disease. All HPAI are of the H5 and H7 subtype and responsible for large avian epidemics to date. […] Human infection results from close contact with infected poultry (secretions and excrement) or contaminated surfaces. […] The first documented human infection with an avian influenza virus occurred in Hong Kong in 1997, when the H5N1 strain caused severe respiratory disease in 18 humans, of whom 6 died. […] The H7N7 subtype was responsible for another outbreak in the Netherlands in 2003 when 83 cases of conjunctivitis and one death from severe respiratory illness were reported.

• #1 Avian influenza: MedlinePlus Medical EncyclopediaLock

  https://medlineplus.gov/ency/article/007263.htm

  Avian influenza A viruses cause the influenza (flu) infection in birds. These viruses occur in wild birds and can infect domestic poultry. The viruses that cause the disease in birds can change their genes (mutate) so they can spread to other animals and humans. […] The first avian influenza in humans was reported in Hong Kong in 1997. It was called avian influenza (H5N1). The outbreak was linked to chickens. […] Since then, there have been human cases of avian influenza A in Asia, Africa, Europe, Indonesia, Vietnam, the Pacific, and the Near East. The virus has caused illness and even death in humans. While rare, avian influenza has also spread to humans in the United States. […] The latest outbreak in the United States started in 2022 and has affected over 1,100 flocks of birds in 48 states.

• #1

  https://www.ncid.sg/Health-Professionals/Diseases-and-Conditions/Pages/Avian-Influenza.aspx

  In the 2004 outbreaks involving H5N1 subtype in Thailand and Vietnam, human cases were associated with severe respiratory disease and high mortality. […] Almost all human cases had antecedent avian exposure during a coincident avian influenza outbreak among chickens. […] Oseltamivir remains the primary recommended antiviral therapy. […] Oseltamivir resistance can emerge during therapy for avian H5N1 and may be associated with clinical deterioration. […] Surveillance of affected flocks and culling (killing) of sick and exposed birds are the most effective methods of controlling an epidemic.

• #1

  https://www.who.int/news-room/questions-and-answers/item/influenza-h5n1

  H5N1 is one of several influenza viruses that causes a highly infectious respiratory disease in birds called avian influenza (or „bird flu”). Infections in mammals, including humans, have also been documented. […] The H5N1 virus remains as an animal virus that primarily infects animals. So far, close to 900 human infections have been reported since 2003, of which more than half were fatal. The H5N1 virus is constantly evolving and could potentially become easily transmissible from person to person. If this occurs, it could be the start of a new influenza pandemic, as was the case with the 1918 and 2009 H1N1 pandemics. […] H5N1 virus has also been detected in samples collected from people without symptoms who had exposure to infected animals or their environments.

• #1 What Causes Bird Flu Virus Infections in Humans | Bird Flu | CDC

  https://www.cdc.gov/bird-flu/virus-transmission/avian-in-humans.html

  Avian influenza or bird flu refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses. […] Although avian (bird) influenza (flu) A viruses usually do not infect people, there have been some rare cases of human infection with these viruses. […] Avian influenza A(H7N9) virus and highly pathogenic avian influenza (HPAI) A(H5N1) and A(H5N6) viruses have been responsible for most human illness from avian influenza viruses reported worldwide to date, including the most serious illnesses with high mortality. […] Human infections with avian influenza viruses can happen when virus gets into a person’s eyes, nose or mouth, or is inhaled. […] In late March 2024, a human case of influenza A(H5N1) virus infection was identified after exposure to dairy cattle presumably infected with bird flu.

• #1 Bird flu (avian influenza) – Symptoms and causes – Mayo Clinic

  https://www.mayoclinic.org/diseases-conditions/bird-flu/symptoms-causes/syc-20568390

  Bird flu, also called avian influenza, is caused by influenza type A virus infections in bird species. […] Bird flu rarely infects humans. But health officials worry because influenza A viruses that infect birds can change, called mutate, to infect humans and spread from person to person more often. […] Influenza is caused by viruses that infect the cells that line the nose, throat and lungs. […] Flu virus particles spread through breath, saliva, mucus or stool. Bird flu in humans can happen when you inhale virus particles. […] People most often catch bird flu from close, long-term contact with live, domesticated poultry typically on farms or in backyard coops. Rarely, people are exposed to bird flu by contact with wild birds or another type of animal. […] It may be possible to be exposed to bird flu through undercooked foods, such as eggs or poultry.

• #1 Bird Flu (Avian Influenza): Causes, Symptoms, and Treatment

  https://www.webmd.com/cold-and-flu/what-know-about-bird-flu

  Bird flu is caused by influenza A viruses. […] People catch bird flu by close contact with an animals fluids, such as saliva, respiratory droplets, or droppings (poop). […] In the 2014 outbreak, some people caught H5N1 from cleaning or plucking infected birds. […] It’s also possible that some people were infected after swimming or bathing in water contaminated with the droppings of infected birds. […] People don’t catch the virus from eating fully cooked chicken or eggs. […] There have been a few cases where one infected person caught the bird flu virus from another person, but only after close personal contact. […] After scientists found H5N1 in dairy cows in March 2024, the FDA started testing retail milk and other milk products for the virus. […] But milk and milk products that havent gone through the pasteurization process are at a higher risk of having the virus.

• #1 Bird Flu Is Raising Red Flags Among Health Officials | Johns Hopkins | Bloomberg School of Public Health

  https://publichealth.jhu.edu/2025/bird-flu-is-raising-red-flags-among-health-officials

  H5N1 is a dynamic virus that poses an increasing threat in terms of spillover and pandemic potential. […] To make matters worse, samples taken from the individual suggest that the virus mutated within the patient after infection meaning it had begun to adapt to infect humans better raising new questions about H5N1’s pandemic potential. […] H5N1 is a very dynamic virus. There’s lots of versions of it circulating in lots of different animals and birds, and it’s continuing to pose a greater and greater threat in terms of spillover and leading to a pandemic. […] The critical thing is understanding whether the virus that’s in dairy cows right now will pick up mutations that will help it to be more transmissible in mammals. […] If the virus changes the way it transmits and becomes a respiratory pathogen among dairy cows, that would be another sign that this virus is changing and posing more of a risk to the human population.

• #1 Avian Influenza (Bird Flu) | Erie County Department of Health (ECDOH)

  https://www3.erie.gov/health/avian-influenza-bird-flu

  Infected birds can shed the viruses in their saliva, nose secretions, and feces. Susceptible birds become infected when they have contact with the virus that was shed by infected birds. They also can become infected through contact with surfaces that are contaminated with virus from infected birds. […] We are still learning about how cows spread avian influenza to other cows. One possible way it spreads on farms is through „fomite transmission” (spread through contaminated objects). […] Although bird flu viruses mainly infect and spread among wild migratory water birds and domestic poultry, some bird flu viruses can infect and spread to other animals as well. […] Although avian (bird) influenza (flu) A viruses usually do not infect people, there have been some rare cases of human infection with these viruses.

• #1 Avian Influenza Outbreak: Should You Take Down Your Bird Feeders? | All About Birds

  https://www.allaboutbirds.org/news/avian-influenza-outbreak-should-you-take-down-your-bird-feeders/

  The main concern with songbirds is the chance that a rare individual might transmit an infection to poultry. […] Avian influenza is only rarely transmitted to humans, according to the USDA. […] The Centers for Disease Control and Prevention considers the general public health risk from avian flu to be low. […] There have also been reports of mammals such as red foxes, skunks, bobcats, fishers, and bears infected with avian influenza, likely from eating infected birds.

• #1 What Causes Bird Flu Virus Infections in Humans | Bird Flu | CDC

  https://www.cdc.gov/bird-flu/virus-transmission/avian-in-humans.html

  The spread of bird flu viruses from one infected person to a close contact is very rare, and when it has happened, it has only spread to a few people. […] However, because of the possibility that bird flu viruses could change and gain the ability to spread easily between people, monitoring for human infection and person-to-person spread is extremely important for public health.

• #1

  https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)

  Human infections with avian and other zoonotic influenza viruses, though rare, have been reported sporadically. […] Current zoonotic influenza viruses have not demonstrated sustained person-to-person transmission. […] Whether currently circulating avian, swine and other influenza viruses will result in a future pandemic is unknown. […] The case fatality rate for A(H5) and A(H7N9) subtype virus infections among humans is higher than that of seasonal influenza infections. […] Influenza viruses are impossible to eradicate and zoonotic infections will continue to occur.

• #1

  https://www.health.nsw.gov.au/Infectious/factsheets/Pages/avian-influenza.aspx

  The risk of human avian influenza infection from consuming animal products from areas with avian influenza is very low. […] You may be at higher risk of getting avian influenza if you travel to countries with avian influenza and have contact with sick birds and other infected animals. […] There is no specific vaccine for avian influenza but the seasonal influenza (flu) vaccination can help prevent co-infection with multiple influenza strains. […] Antiviral medicines for human influenza (flu) can also prevent severe illness from avian influenza.

• #1 Bird flu (avian influenza) | Better Health Channel

  https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/bird-flu-avian-influenza

  Bird flu, also known as avian influenza, is an infectious disease of birds and is caused by several different strains of the bird flu virus. It spreads between both wild and domesticated birds and very rarely spreads from birds to humans. Human cases of bird flu are usually people in close contact with infected poultry or other birds. […] There are different strains of bird flu, some that are more likely to cause death and disease in birds (highly pathogenic) and some that are less likely to cause death and disease (low pathogenic). […] Wild birds are believed to be the carriers of bird flu viruses. […] Bird flu viruses typically kill domesticated birds, such as chickens and turkeys. […] You can’t catch avian influenza through eating fully cooked poultry or eggs, even in areas with an outbreak of bird flu. […] Several anti-viral medications used to treat human flu are also effective for bird flu.

• #1 Frequently Asked Questions | MS Avian Influenza

  https://www.hpai.ms.gov/information/frequently-asked-questions/

  The likelihood of avian influenza-infected poultry entering the U.S. food supply is extremely low due to import restrictions, extensive disease testing programs, and state/federal inspection programs. […] Properly prepared and cooked poultry is safe to eat so not a source of AI virus infection of any strain. Cooking poultry to an internal temperature of 165 degrees Fahrenheit kills the AI virus, as well as other organisms.

• #1 Investigation of Avian Influenza A (H5N1) Virus in Dairy Cattle | FDA

  https://www.fda.gov/food/alerts-advisories-safety-information/investigation-avian-influenza-h5n1-virus-dairy-cattle

  The U.S. Department of Agriculture (USDA), the U.S. Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC), along with state partners, continue to investigate an outbreak of Avian Influenza A (H5N1) impacting poultry, dairy cows, and people in multiple states. […] The FDA has sampled a total of 464 pasteurized dairy products, including milk, cheese, butter, and ice cream, all were negative for viable H5N1. In addition, multiple research studies have confirmed that pasteurization inactivates the virus. […] Research Results from Cornell University Suggest that the Aging Process Alone May Not Be Effective in Eliminating Viable H5N1 in Raw Milk Cheese. […] The FDA is confident that pasteurization is effective at inactivating H5N1, and that the commercial, pasteurized milk supply is safe.

• #1 Bird Flu | Influenza A | Avian Flu | MedlinePlus

  https://medlineplus.gov/birdflu.html

  Birds, just like people, can get the flu. Another name for bird flu is avian influenza. The viruses that cause bird flu normally only infect birds, including chickens, other poultry, and wild birds such as ducks. But sometimes the viruses can infect other animals and, in rare cases, people. […] A few types of these viruses have caused most of the infections in people. They are the H5N1, H7N9, and H5N6 viruses. These infections in people have mainly been in Asia, Africa, Europe, the Pacific, and the Near East. Although it’s very rare, there have also been some infections in people in the United States. […] Bird flu can also infect many other animals, including some dogs, cats, certain wild and zoo animals, and livestock such as cattle. These animals can then spread the flu to people. […] Certain people may be more likely to get bird flu, including poultry workers, animal handlers, wildlife biologists, disease control workers, research laboratory workers, veterinarians, and people who travel to countries where bird flu is present.

• #1 Avian Influenza – Overview | Occupational Safety and Health Administration

  http://www.osha.gov/avian-flu

  Avian Influenza H5N1 was first seen in the U.S. in wild, migratory birds in 2015, and in agricultural poultry stock beginning in 2022. While there is currently no evidence of person to person spread, a small number of workers exposed to infected animals have been infected with H5N1. Since 2022, millions of birds have been culled because of bird flu infection in the United States. H5N1 infections in mammals have since been reported across the U.S., Canada, and other parts of the world. The 2024 infections among dairy herds were the first reported instances of H5N1 causing disease in cattle. […] People who work in operations with poultry (including eradication of sick birds), cattle and other livestock (dairy, meatpacking, etc.) and their byproducts (viscera, raw milk, etc.) should take extra precautions to reduce the risk of H5N1 exposure and illness.

• #1 H5N1 Bird Flu: What You Need to Know > News > Yale Medicine

  https://www.yalemedicine.org/news/h5n1-bird-flu-what-to-know

  Avian influenza A (H5N1), or bird flu, has killed millions of wild birds, and caused sporadic outbreaks among poultry and an ongoing multistate outbreak among cows in the United States. […] Most of the human cases of H5N1 have involved people working on farms where they were exposed to sick cows or poultry in California, Colorado, Iowa, Louisiana, Michigan, Oregon, Texas, Washington, and Wisconsin. […] Both pigs and dairy cows are new and unexpected hosts of the H5N1 virus, and the spread of the virus among cows is a sign that it could mutate in them, making it easier for it to spread to other animals or potentially humans, according to the CDC. […] Experts have been concerned about the possibility of the virus infecting pigs at some point, because pigs have been infected in the past with both human and animal flu viruses, adds Dr. Roberts.

• #1 H5N1 bird flu: Symptoms, causes, and diagnosis

  https://www.medicalnewstoday.com/articles/5556

  Avian flu, or bird flu, refers to a group of diseases that result from infections with specific influenza viruses. These viruses infect birds but rarely spread to humans. […] One virus that causes bird flu is called H5N1. The H5N1 virus can cause severe flu with a high mortality rate. […] H5N1 bird flu is fatal in 60% of cases. […] Humans can acquire the infection and develop the illness after coming into unprotected contact with birds who are carrying the virus. Human-to-human transmission is rare. […] According to the Food and Agriculture Organization of the U. S., the following activities may lead to the illness in humans: touching infected birds, touching or breathing in feces or other secretions of infected birds, preparing infected poultry for cooking, slaughtering or butchering infected poultry, handling birds for sale, attending markets that sell live birds. […] Bird droppings may contain the virus and can contaminate feed, equipment, vehicles, shoes, clothing, soil, dust, and water. […] H5N1 bird flu can cause severe symptoms, and it has a high mortality rate. However, the virus does not transmit easily among humans, and the risk of a pandemic is low.

• #1

  https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)

  Humans can be infected with avian, swine and other influenza viruses. […] Direct contact with infected animals (through handling, culling, slaughtering or processing) or indirect contact (through environments contaminated with bodily fluids from infected animals) represent a risk for human infection. […] Exposure to animal influenza viruses can lead to infection and disease in humans ranging from mild, flu-like symptoms or eye inflammation to severe, acute respiratory disease and/or death. […] For avian influenza viruses, the primary risk factor for human infection appears to be exposure to infected live or dead poultry or contaminated environments, such as live bird markets. […] There is no evidence to suggest that A(H5), A(H7N9) or other avian influenza viruses can be transmitted to humans through properly prepared and cooked poultry or eggs.

• #1 Avian influenza

  https://tephi.texas.gov/training/selected-outbreaks/avianinfluenza

  Asymptomatic H5N1 human cases have been observed. […] With each human case, it is more likely that the H5N1 influenza virus will change and its possible that these changes may lead to greater communicability or more severe disease in humans. […] Reassortment is known to happen in pigs, which may lead to changes in the virus to be more easily transmitted from human to human or cause more severe disease.

• #1 Avian Influenza – Infectious Diseases – MSD Manual Professional Edition

  https://www.msdmanuals.com/professional/infectious-diseases/respiratory-viruses/avian-influenza

  Because all influenza viruses are capable of rapid genetic change, avian strains could possibly acquire the ability to spread more easily from person-to-person via direct mutation or via reassortment of genome subunits with human strains during replication in a human, animal or, avian host. If these strains acquire the ability to spread efficiently from person to person, an influenza pandemic could result. […] Human infection is typically acquired from infected birds although human-to-human transmission has occurred.

• #1 How bird flu differs from seasonal flu − an infectious disease researcher explainsverifiedverifiedverifiedverifiedverifiedverifiedverifiedverifiedverifiedverified

  https://www.gavi.org/vaccineswork/how-bird-flu-differs-seasonal-flu-infectious-disease-researcher-explains

  The first major outbreak of H5 family avian flu occurred in North America in 2014-2015. This 2014 outbreak was caused by the H5N8 strain, a close relative of H5N1. […] As of March 21, 2025, there have been 988 human cases of H5N1 worldwide since 1997, about half of which resulted in death. The current outbreak in the U.S. accounts for 70 of those infections and one death. Importantly, there have been no reports of H5N1 spreading directly from one person to another. […] It is possible for this type of transformation to also occur in H5N1. The CDC monitors which strains of flu are circulating in order prepare for that possibility. Additionally, the U.S. Department of Agriculture has a surveillance system for monitoring potential threats for spillover from birds and other animals, although this capacity may be at risk due to staff cuts in the department.

• #1 Bird Flu: Symptoms, Causes, and Risk Factors

  https://www.healthline.com/health/avian-influenza

  Bird flu, also called avian influenza, is a viral infection that can infect not only birds, but also humans and other animals. Most forms of the virus are restricted to birds. […] H5N1 is the most common form of bird flu. Its deadly to birds and can easily affect humans and other animals that come in contact with a carrier. According to the World Health Organization, H5N1 was first discovered in humans in 1997 and has killed nearly 60 percent of those infected. […] Although there are several types of bird flu, H5N1 was the first avian influenza virus to infect humans. The first infection occurred in Hong Kong in 1997. The outbreak was linked to handling infected poultry. […] H5N1 occurs naturally in wild waterfowl, but it can spread easily to domestic poultry. The disease is transmitted to humans through contact with infected bird feces, nasal secretions, or secretions from the mouth or eyes.

• #1 Avian influenza A(H5N1): Symptoms and treatment – Canada.ca

  https://www.canada.ca/en/public-health/services/diseases/avian-influenza-h5n1.html

  Avian influenza is a contagious viral infection that mainly affects birds but can sometimes infect humans and other mammals. […] Avian influenza A(H5N1) illness is caused by the avian influenza A(H5N1) virus. […] Approximately half of the over 900 human cases reported around the world since 1997 (mostly in Africa and Asia), have been fatal.

• #1 Bird Flu: Outbreak, Symptoms, Treatment, Types, Spread & Risks

  https://www.medicinenet.com/avian_influenza_bird_flu/article.htm

  Bird flu (avian flu or avian influenza) refers to strains of influenza that primarily affect wild and domesticated birds but can occasionally and sporadically infect humans. […] Bird flu is caused by strains of the influenza virus that have evolved to be specially adapted to enter avian cells. There are three main types of influenza: A, B, and C. The virus that causes bird flu is influenza A type with eight RNA strands that make up its genome. […] The history of bird flu in humans is short. The first human case of illness from highly pathogenic avian influenza (termed HPAI in older literature) was identified in 1997. […] Human infection with highly infectious strains of bird flu is uncommon, with most infections occurring after exposure to infected birds or their droppings. […] The prognosis in human cases of bird flu remains poor. Many cases occur in people who are poor, live in rural areas in underdeveloped countries, and do not have access to modern intensive-care units or antiviral therapy. Approximately 55% of people diagnosed with H5N1 bird flu eventually die from the disease; the H7N9 strain has a similar death rate of about 37%. […] Bird flu can be prevented by avoiding contact with sick poultry originating in countries known to be affected by the virus.

• #1 H5N1 Bird Flu: What You Need to Know > News > Yale Medicine

  https://www.yalemedicine.org/news/h5n1-bird-flu-what-to-know

  The first reported case of bird flu in humans in the U.S. was reported in April 2022 in Colorado; a person reported mild symptoms after being exposed to poultry. […] In February 2022, the virus began causing sporadic outbreaks of HPAI H5N1 in backyard and commercial poultry flocks in the U.S., causing serious illness and death in infected chickens. […] Its possible that there are more human cases of bird flu than are being reported. […] The CDC has categorized the risk to the general public as low, and notes that people with exposure to infected animals are at higher risk of infection. […] However, 50% may be an overestimate, Dr. Roberts says, adding that there may be cases where people have no symptoms, are only mildly symptomatic, or havent sought care for their symptoms. […] Another reason for concern is that bird flu is now being detected in new animal species.

• #1 H5N1 bird flu: Questions patients may have and how to answer | American Medical Association

  https://www.ama-assn.org/delivering-care/public-health/h5n1-bird-flu-questions-patients-may-have-and-how-answer

  Antiviral treatment works best when started early after symptoms begin. Antivirals can also be given soon after unprotected exposure to prevent infection and illness. […] There are H5 candidate vaccine viruses that could be used to produce a vaccine. According to the U.S. Department of Health and Human Services assistant secretary for preparedness and response, officials are moving ahead with a plan to produce 4.8 million doses of H5N1 avian flu vaccine for pandemic preparedness. […] Testing for the flu typically declines over the summer, but the CDC is working on a plan for enhanced nationwide monitoring to ensure that even rare cases of A(H5N1) virus in the community are detected.

• #1 Bird Flu | Influenza A | Avian Flu | MedlinePlus

  https://medlineplus.gov/birdflu.html

  Bird flu is treated with antiviral medicines. It’s important to get them as soon as possible. The medicines may make your illness less severe. […] There is currently no vaccine available to the public. The government has developed a virus that is similar to some H5N1 viruses. The virus could be used to produce a vaccine for people, if needed. […] Bird Flu in Animals and People: Causes and How It Spreads (Centers for Disease Control and Prevention) […] What Causes Bird Flu Virus Infections in Humans (Centers for Disease Control and Prevention) […] Avian Influenza in Birds: Causes and How It Spreads (Centers for Disease Control and Prevention)

• #1 Avian influenza Information | Mount Sinai – New York

  https://www.mountsinai.org/health-library/diseases-conditions/avian-influenza

  Avian influenza A viruses cause the influenza (flu) infection in birds. These viruses occur in wild birds and can infect domestic poultry. The viruses that cause the disease in birds can change their genes (mutate) so they can spread to other animals and humans. […] The first avian influenza in humans was reported in Hong Kong in 1997. It was called avian influenza (H5N1). The outbreak was linked to chickens. Since then, there have been human cases of avian influenza A in Asia, Africa, Europe, Indonesia, Vietnam, the Pacific, and the Near East. The virus has caused illness and even death in humans. While rare, avian influenza has also spread to humans in the United States. […] The virus that causes human avian flu is resistant to the antiviral medicines amantadine and rimantadine. These medicines should not be used in the case of an H5N1 infection.

• #1 Avian Influenza (Bird Flu): H5N1, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/22401-bird-flu

  Avian influenza, commonly called bird flu, is a viral infection that spreads in birds, cows and other animals. In humans, H5 subtypes of influenza A are the most common cause. […] Bird flu (avian influenza) is an infection from a type of influenza (flu) virus that usually spreads in birds and other animals. Sometimes, humans can get bird flu from infected animals. […] A type of influenza A virus, often H5N1 in humans, causes bird flu. The virus can infect your upper respiratory tract and lungs, and sometimes spread to other parts of your body like your brain. […] Bird flu spreads in birds, cows and other mammals. It sometimes spreads from animals to people. This is a problem for wildlife health, food supply and human health.

• #1 Avian influenza: MedlinePlus Medical EncyclopediaLock

  https://medlineplus.gov/ency/article/007263.htm

  In March 2024, the virus was detected for the first time in dairy cows. The Centers for Disease Control and Prevention reports at least 16 states where H5N1 bird flu has infected dairy cows. […] Since April 2024, there have been a total of 61 reported cases of H5N1 in humans in the United States. […] Avian flu viruses can live in the environment for long periods of time. Infection may be spread just by touching surfaces that have the virus on them. Birds who were infected with the avian flu can shed the virus in their feces and saliva for as long as 10 days. […] There is an approved vaccine to protect humans from the H5N1 avian flu virus. This vaccine could be used if the current H5N1 virus starts spreading among people. The US government keeps a stockpile of the vaccine.

• #1 Avian Influenza (Bird Flu): Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/2500029-overview

  This spillover raises significant concerns for the dairy industry and highlights the potential for the virus to adapt to new hosts, including humans. […] The ongoing spread of avian influenza, particularly the H5N1 strain, poses significant risks not only to poultry but also to other species, including mammals. The potential for mutations that could enhance transmissibility among mammals raises serious public health concerns. […] The potential for spillover into other species, including mammals, raises significant concerns for public health. Continuous surveillance, enhanced biosecurity measures, and a comprehensive One Health approach are essential to mitigate the risks associated with avian influenza and prevent future outbreaks.

• #1 Avian Influenza in Poultry and Wild Birds – Poultry – Merck Veterinary Manual

  https://www.merckvetmanual.com/poultry/avian-influenza-in-poultry-and-wild-birds/avian-influenza-in-poultry-and-wild-birds

  The H9N2 LPAI virus has caused 132 human cases (2 deaths) in Asia and Africa. […] Most AI viruses (subtypes H1H16) are LPAI viruses. However, some of the H5 and H7 AI viruses are HPAI viruses and highly lethal for chickens, turkeys, and related gallinaceous domestic poultry. […] HPAI must be differentiated from other causes of high mortality rates, such as virulent Newcastle disease, the peracute septicemic form of fowl cholera, heat exhaustion, and severe water deprivation.

• #1 Bird flu

  https://www.nhs.uk/conditions/bird-flu/

  Bird flu, or avian flu, is an infectious type of influenza that spreads among birds. In rare cases, it can affect humans. […] There are lots of different strains of bird flu virus. Most of them don’t infect humans. But there are 4 strains that have caused concern in recent years: H5N1 (since 1997), H7N9 (since 2013), H5N6 (since 2014), H5N8 (since 2016). […] Although H5N1, H7N9 and H5N6 don’t infect people easily and aren’t usually spread from human to human, several people have been infected around the world, leading to a number of deaths. […] In February 2021 H5N8 was found to have infected a small number of people for the first time, in Russia. […] Bird flu is spread by close contact with an infected bird (dead or alive). […] You can’t catch bird flu through eating fully cooked poultry or eggs, even in areas with an outbreak of bird flu.

• #1 Facts about avian influenza – inspection.canada.ca

  http://inspection.canada.ca/en/animal-health/terrestrial-animals/diseases/reportable/avian-influenza/facts-about-avian-influenza

  Avian influenza (AI), often called „bird flu,” is caused by the Type „A” influenza virus. This virus can affect several species of food-producing birds (chickens, turkeys, quails, guinea fowl, etc.), as well as pet and wild birds. […] Avian influenza viruses can be broadly classified into 2 types, based on the severity of the illness caused in birds: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI). […] Most avian influenza viruses are low pathogenic. These typically cause little or no signs of illness in infected birds. […] However, highly pathogenic viruses can cause severe illness and death in birds. […] The „H” gene determines how transmissible a virus will be, which directs our response plan. The H5 and H7 subtypes of the virus are of particular concern, given the ability of these 2 H-types to mutate from low pathogenic to highly pathogenic after they infect domestic birds.

• #1 Avian Influenza (Bird Flu) Fact Sheet | Cornell University College of Veterinary Medicine

  https://www.vet.cornell.edu/highly-pathogenic-avian-influenza-bird-flu-resource-center/avian-influenza-bird-flu-fact-sheet

  This finding suggests that the outbreak in Nevada did not result from contact with an infected cow or contaminated farm equipment, but rather resulted from a new introduction into cattle from wild birds. […] While this new genetic variation (genotype D1.1) does not in and of itself greatly change the risk to cattle or human health, it shows the risk of new introductions from birds into dairy operations. […] Avian influenza can be divided into two categories: highly pathogenic (HPAI) or low pathogenic (LPAI) strains. […] Avian influenza is categorized as HPAI depending on the severity of infection in domestic poultry, such as chickens and turkeys. […] Technically, a strain is defined as HPAI if it kills at least 75% of 4- to 6-week-old chickens within 10 days of infection. […] Practically, however, classification is based on whether there is systemic infection – infection that spreads beyond the respiratory tract – or if infection remains local to the respiratory system. […] The H5 and H7 subtypes are the most common causes of HPAI, and are also the subtypes that are most likely to infect humans. The current outbreak of HPAI is due to an H5N1 subtype.

• #1 H5N1 Avian Influenza (Bird Flu) From Dairy Cows – Your Questions, Answered | EBSCO

  https://www.ebsco.com/blogs/health-notes/h5n1-avian-influenza-bird-flu-dairy-cows-your-questions-answered

  Cases of H5N1 avian influenza virus have been reported in the United States in 2024. […] All cases are presumed to have acquired bird flu from infected dairy cows. […] The H5N1 avian influenza virus causing infections in dairy farm workers isn’t new. This strain of bird flu was first detected in humans in Asia in the 1990s and has continued to circulate among birds since then, causing occasional spillover cases in humans. […] Cows are an intermediary host, meaning that they are getting infected from birds (possibly by consuming grasses contaminated with bird feces). This is the first time that H5N1 bird flu has ever been detected in cows, and currently 168 dairy farms in the United States have reported positive H5N1 testing in their herds. […] The cases of H5N1 infection in dairy farm workers are associated with close contact with infected cows and it is thought that they may have acquired the infection during the milking process.

• #1 It’s like 'dead birds flying’: How bird flu is spreading in the wild : Goats and Soda : NPR

  https://www.npr.org/sections/goats-and-soda/2025/02/07/g-s1-46402/bird-flu-wild-animals-mammals-virus

  Bird flu is taking a massive toll on wild animals, researchers find. Dead from bird flu. […] The particular virus that causes bird flu H5N1 itself is not new. It’s a disease that originated in east Asia, first detected in China in 1996. […] The virus evolved so some wild birds are able to migrate just far enough to reach another bird community or mammal population to pass the virus on before dying. […] Scientists are still trying to understand exactly how the virus spreads between animals. […] Each animal that is infected particularly mammals is another chance for the virus to evolve and become better suited to infecting people. […] At the moment, the virus can infect humans but has not yet evolved to jump readily from one human to another. That could change.

• #1 CDC review of two more US H5N1 viruses similar to earlier assessments | CIDRAP

  https://www.cidrap.umn.edu/avian-influenza-bird-flu/cdc-review-two-more-us-h5n1-viruses-similar-earlier-assessments

  The US Centers for Disease Control and Prevention (CDC) on May 2 published assessments for two more H5N1 avian flu clade 2.3.4.4b viruses, noting that the risk is moderate, similar to that posed by other recent viruses from the same clade. […] One is a 2024 B3.13 genotype virus from California that is similar to those currently circulating in US dairy cattle and causes sporadic human infections, mainly in people who are exposed to sick cows. The other is a 2024 D1.1 genotype virus from Washington that resembles one circulating in wild birds and poultry, with occasional jumps to humans who have poultry exposure. […] The CDC said the new assessments weave in new information, including information from human cases. […] Potential emergence scores for the California and Washington viruses were 5.59 and 5.21, respectively, putting them at the mid-low range of the moderate risk category. […] The group said the susceptibility and occasional transmission they identified are worrisome from a public health perspective, given that pigs are susceptible to both mammalian and avian influenza virus, making them a mixing vessel for new reassortants.

• #1 Avian influenza in pets and backyard flocks | American Veterinary Medical Associationmultiple-users-1

  https://www.avma.org/resources-tools/animal-health-and-welfare/animal-health/avian-influenza/avian-influenza-companion-animals

  Potential sources of H5N1 infection for cats and possibly dogs include: Unpasteurized milk, cream, or colostrum; Raw or undercooked meat, especially poultry; Sick or dead infected birds; People who work on affected farms or their contaminated clothing. […] People also may become infected through exposure to infected animals. This is uncommon but does happen, typically involving close or prolonged exposure to infected poultry or dairy cows. At least one case of human H5N1 infection has been linked to exposure to sick and dead birds in backyard flocks. […] Numerous cases of HPAI have been reported in backyard flocks in the U.S. Although pet (possibly caged) birds are unlikely to be exposed to wild birds, the rare possibility remains that pet birds could catch HPAI, too. Currently, no vaccine is authorized for animals in the U.S.

• #1 H5N1 bird flu: Questions patients may have and how to answer | American Medical Association

  https://www.ama-assn.org/delivering-care/public-health/h5n1-bird-flu-questions-patients-may-have-and-how-answer

  Concerns swirl across the country as highly pathogenic avian influenza (HPAI) A(H5N1) virus commonly known as avian influenza or H5 bird flu once again takes flight. This avian influenza strain has killed millions of wild birds and caused sporadic outbreaks among poultry. […] HPAI A(H5N1) virus is a type of influenza virus that causes highly infectious and severe respiratory disease in birds. That is why it is called avian influenza or bird flu. It is causing outbreaks in poultry and dairy cows in the U.S. […] The risk of A(H5N1) virus infection is low for the general public in the U.S. But people who work with birds, poultry or cows, or have recreational exposure to them, are at higher risk. […] People rarely get A(H5N1) virus infections, but when they do, it is most often acquired through close, prolonged and unprotected contact with infected birds or other animals.

• #2 Avian Influenza (Bird Flu): H5N1, Causes, Symptoms & Treatment

  https://my.clevelandclinic.org/health/diseases/22401-bird-flu

  Avian influenza, commonly called bird flu, is a viral infection that spreads in birds, cows and other animals. In humans, H5 subtypes of influenza A are the most common cause. […] Bird flu (avian influenza) is an infection from a type of influenza (flu) virus that usually spreads in birds and other animals. Sometimes, humans can get bird flu from infected animals. […] A type of influenza A virus, often H5N1 in humans, causes bird flu. The virus can infect your upper respiratory tract and lungs, and sometimes spread to other parts of your body like your brain. […] Bird flu spreads in birds, cows and other mammals. It sometimes spreads from animals to people. This is a problem for wildlife health, food supply and human health.

• #2 Pathology, Molecular Biology, and Pathogenesis of Avian Influenza A (H5N1) Infection in Humans

  https://pmc.ncbi.nlm.nih.gov/articles/PMC2329826/

  H5N1 avian influenza is a highly fatal infectious disease that could cause a potentially devastating pandemic if the H5N1 virus mutates into a form that spreads efficiently among humans. […] Dysregulation of cytokines and chemokines is likely to be one of the key mechanisms in the pathogenesis of H5N1 influenza. […] H5N1 influenza is still a relatively novel disease with poorly understood pathology and pathogenesis. […] The major pathogenetic mechanisms and etiological factors of H5N1 influenza are discussed. […] The various molecular determinants of increased pathogenicity of H5N1 avian influenza viruses that have been identified in recent years are also presented. […] H5N1 influenza appears to be a systemic infection in both human and animal cases. […] It appears that the virus may also spread to other organs, such as the kidneys and liver, as has also been demonstrated in animals.

• #2 Bird flu (avian influenza) | RIVM

  https://www.rivm.nl/en/bird-flu

  Avian flu (avian influenza, also known as bird flu) is a contagious disease primarily found in birds. Various influenza viruses that can cause avian flu have been observed worldwide. […] Avian flu affects the respiratory system (nose, mouth and airways), digestive system and/or nervous system. […] Highly pathogenic avian influenza (HPAI) is deadly to birds. […] Low pathogenic avian influenza (LPAI) causes minimal or no symptoms in birds. […] In rare cases, avian influenza viruses can be transmitted from animals to humans. This only happens after extended close contact between humans and infected animals (birds or mammals). […] Some types of avian influenza, especially in Asia, can sometimes make people very ill. In these cases, they cause severe pneumonia or shortness of breath. […] There has been a striking increase in avian flu among waterfowl in the Netherlands. Avian flu has become a pandemic among these birds, affecting very high numbers of waterfowl worldwide.

• #2 Facts about avian influenza – inspection.canada.ca

  http://inspection.canada.ca/en/animal-health/terrestrial-animals/diseases/reportable/avian-influenza/facts-about-avian-influenza

  Avian influenza (AI), often called „bird flu,” is caused by the Type „A” influenza virus. This virus can affect several species of food-producing birds (chickens, turkeys, quails, guinea fowl, etc.), as well as pet and wild birds. […] Avian influenza viruses can be broadly classified into 2 types, based on the severity of the illness caused in birds: low pathogenic avian influenza (LPAI) and highly pathogenic avian influenza (HPAI). […] Most avian influenza viruses are low pathogenic. These typically cause little or no signs of illness in infected birds. […] However, highly pathogenic viruses can cause severe illness and death in birds. […] The „H” gene determines how transmissible a virus will be, which directs our response plan. The H5 and H7 subtypes of the virus are of particular concern, given the ability of these 2 H-types to mutate from low pathogenic to highly pathogenic after they infect domestic birds.

• #2 What Causes Bird Flu Virus Infections in Humans | Bird Flu | CDC

  https://www.cdc.gov/bird-flu/virus-transmission/avian-in-humans.html

  Avian influenza or bird flu refers to the disease caused by infection with avian (bird) influenza (flu) Type A viruses. […] Although avian (bird) influenza (flu) A viruses usually do not infect people, there have been some rare cases of human infection with these viruses. […] Avian influenza A(H7N9) virus and highly pathogenic avian influenza (HPAI) A(H5N1) and A(H5N6) viruses have been responsible for most human illness from avian influenza viruses reported worldwide to date, including the most serious illnesses with high mortality. […] Human infections with avian influenza viruses can happen when virus gets into a person’s eyes, nose or mouth, or is inhaled. […] In late March 2024, a human case of influenza A(H5N1) virus infection was identified after exposure to dairy cattle presumably infected with bird flu.

• #2 Avian Influenza – Overview | Occupational Safety and Health Administration

  http://www.osha.gov/avian-flu

  Commonly known as avian flu or bird flu, avian influenza is a disease caused by infection with avian (bird) influenza (flu) Type A viruses. These viruses naturally spread among wild aquatic birds worldwide, including ducks, geese, swans, and storks, and can infect domesticated birds like chickens and turkeys. Some bird flu viruses can infect and spread to other animals as well. Bird flu viruses do not normally infect humans. However, sporadic human infections with bird flu viruses have occurred. […] While uncommon, workers can be infected after unprotected exposure to infected birds/animals when enough virus gets into a person’s eyes, nose, or mouth, is inhaled, or when a person touches something that has virus on it and then touches their mouth, eyes, or nose. Animals with avian flu shed the virus in their bodily fluids.

• #2 Pathology, Molecular Biology, and Pathogenesis of Avian Influenza A (H5N1) Infection in Humans

  https://pmc.ncbi.nlm.nih.gov/articles/PMC2329826/

  Various factors are thought to be involved in the pathogenesis of H5N1 influenza, and a combination of these factors most likely determines the extent of tissue injury and disease outcome. […] The role of dysregulation of cytokines and chemokines has been studied extensively and may be one of the key mechanisms in the pathogenesis of H5N1 influenza, in addition to injury resulting from viral replication. […] Up-regulation of functional TRAIL in macrophages infected with the H5N1 virus may be another important factor in the pathogenesis of H5N1 influenza virus infection. […] H5N1 viral replication appears to be prolonged with high levels of viral RNA, and the virus may disseminate to extra-pulmonary organs. […] The NS gene of H5N1 viruses may also account for up-regulation of cytokines and chemokines. […] The presence of glutamic acid at position 92 of NS1 appeared to be a prerequisite for the resistance to antiviral cytokines. […] In fact virulence appears to be a polygenic trait with several genes co-operating together.

• #2 Avian Influenza – Infectious Diseases – MSD Manual Professional Edition

  https://www.msdmanuals.com/professional/infectious-diseases/respiratory-viruses/avian-influenza

  Because all influenza viruses are capable of rapid genetic change, avian strains could possibly acquire the ability to spread more easily from person-to-person via direct mutation or via reassortment of genome subunits with human strains during replication in a human, animal or, avian host. If these strains acquire the ability to spread efficiently from person to person, an influenza pandemic could result. […] Human infection is typically acquired from infected birds although human-to-human transmission has occurred.

• #2 Avian Influenza (Bird Flu): Background, Pathophysiology, Epidemiology

  https://emedicine.medscape.com/article/2500029-overview

  The spillover of avian influenza into other species is facilitated by several factors: […] Genetic Reassortment: The segmented nature of the influenza A virus genome allows for genetic reassortment when a host is co-infected with multiple strains. This can result in the creation of new viral strains with altered antigenic properties, potentially evading the immune response of existing hosts. […] Host Susceptibility: Certain strains of avian influenza have shown a preference for specific receptors found in different species. For example, the receptor usage of the virus can determine its ability to infect mammals. The presence of sialic acid receptors, which bind to hemagglutinin, plays a crucial role in the virus’s ability to infect various hosts. […] Recent findings have highlighted the ongoing threat of avian influenza, particularly the H5N1 strain, to both animal and human health:

• #2 Avian influenza: MedlinePlus Medical EncyclopediaLock

  https://medlineplus.gov/ency/article/007263.htm

  Avian influenza A viruses cause the influenza (flu) infection in birds. These viruses occur in wild birds and can infect domestic poultry. The viruses that cause the disease in birds can change their genes (mutate) so they can spread to other animals and humans. […] The first avian influenza in humans was reported in Hong Kong in 1997. It was called avian influenza (H5N1). The outbreak was linked to chickens. […] Since then, there have been human cases of avian influenza A in Asia, Africa, Europe, Indonesia, Vietnam, the Pacific, and the Near East. The virus has caused illness and even death in humans. While rare, avian influenza has also spread to humans in the United States. […] The latest outbreak in the United States started in 2022 and has affected over 1,100 flocks of birds in 48 states.

• #2 How bird flu differs from seasonal flu − an infectious disease researcher explainsverifiedverifiedverifiedverifiedverifiedverifiedverifiedverifiedverifiedverified

  https://www.gavi.org/vaccineswork/how-bird-flu-differs-seasonal-flu-infectious-disease-researcher-explains

  The first major outbreak of H5 family avian flu occurred in North America in 2014-2015. This 2014 outbreak was caused by the H5N8 strain, a close relative of H5N1. […] As of March 21, 2025, there have been 988 human cases of H5N1 worldwide since 1997, about half of which resulted in death. The current outbreak in the U.S. accounts for 70 of those infections and one death. Importantly, there have been no reports of H5N1 spreading directly from one person to another. […] It is possible for this type of transformation to also occur in H5N1. The CDC monitors which strains of flu are circulating in order prepare for that possibility. Additionally, the U.S. Department of Agriculture has a surveillance system for monitoring potential threats for spillover from birds and other animals, although this capacity may be at risk due to staff cuts in the department.

• #2 Avian influenza: MedlinePlus Medical EncyclopediaLock

  https://medlineplus.gov/ency/article/007263.htm

  In March 2024, the virus was detected for the first time in dairy cows. The Centers for Disease Control and Prevention reports at least 16 states where H5N1 bird flu has infected dairy cows. […] Since April 2024, there have been a total of 61 reported cases of H5N1 in humans in the United States. […] Avian flu viruses can live in the environment for long periods of time. Infection may be spread just by touching surfaces that have the virus on them. Birds who were infected with the avian flu can shed the virus in their feces and saliva for as long as 10 days. […] There is an approved vaccine to protect humans from the H5N1 avian flu virus. This vaccine could be used if the current H5N1 virus starts spreading among people. The US government keeps a stockpile of the vaccine.

• #2 Avian Influenza (Bird Flu) Fact Sheet | Cornell University College of Veterinary Medicine

  https://www.vet.cornell.edu/highly-pathogenic-avian-influenza-bird-flu-resource-center/avian-influenza-bird-flu-fact-sheet

  Like all viruses, influenza viruses can change over time. Every time an animal or person is infected, small changes in the genetic sequence of the virus occur, and these help the virus avoid getting cleared by the immune system. […] Large genetic changes can also occur when one individual is infected with more than one type of influenza virus and the viruses mix their genetic material. This can result in new forms of the virus that suddenly gain the ability to infect new species. […] Avian influenza can be transmitted in three ways: Direct contact, Indirect contact (e.g. contaminated surfaces), Inhalation. […] Infected birds (whether showing symptoms or not) can shed the virus in saliva, ocular, nasal or oral secretions, and feces. […] The consumption of raw foods, including raw milk and raw milk products, poses known risks of transmission and should be avoided by domestic cats and people.

• #2

  https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)

  Humans can be infected with avian, swine and other influenza viruses. […] Direct contact with infected animals (through handling, culling, slaughtering or processing) or indirect contact (through environments contaminated with bodily fluids from infected animals) represent a risk for human infection. […] Exposure to animal influenza viruses can lead to infection and disease in humans ranging from mild, flu-like symptoms or eye inflammation to severe, acute respiratory disease and/or death. […] For avian influenza viruses, the primary risk factor for human infection appears to be exposure to infected live or dead poultry or contaminated environments, such as live bird markets. […] There is no evidence to suggest that A(H5), A(H7N9) or other avian influenza viruses can be transmitted to humans through properly prepared and cooked poultry or eggs.

• #2 H5N1 Bird Flu: What You Need to Know > News > Yale Medicine

  https://www.yalemedicine.org/news/h5n1-bird-flu-what-to-know

  Avian influenza A (H5N1), or bird flu, has killed millions of wild birds, and caused sporadic outbreaks among poultry and an ongoing multistate outbreak among cows in the United States. […] Most of the human cases of H5N1 have involved people working on farms where they were exposed to sick cows or poultry in California, Colorado, Iowa, Louisiana, Michigan, Oregon, Texas, Washington, and Wisconsin. […] Both pigs and dairy cows are new and unexpected hosts of the H5N1 virus, and the spread of the virus among cows is a sign that it could mutate in them, making it easier for it to spread to other animals or potentially humans, according to the CDC. […] Experts have been concerned about the possibility of the virus infecting pigs at some point, because pigs have been infected in the past with both human and animal flu viruses, adds Dr. Roberts.

• #2 Avian influenza in pets and backyard flocks | American Veterinary Medical Associationmultiple-users-1

  https://www.avma.org/resources-tools/animal-health-and-welfare/animal-health/avian-influenza/avian-influenza-companion-animals

  Potential sources of H5N1 infection for cats and possibly dogs include: Unpasteurized milk, cream, or colostrum; Raw or undercooked meat, especially poultry; Sick or dead infected birds; People who work on affected farms or their contaminated clothing. […] People also may become infected through exposure to infected animals. This is uncommon but does happen, typically involving close or prolonged exposure to infected poultry or dairy cows. At least one case of human H5N1 infection has been linked to exposure to sick and dead birds in backyard flocks. […] Numerous cases of HPAI have been reported in backyard flocks in the U.S. Although pet (possibly caged) birds are unlikely to be exposed to wild birds, the rare possibility remains that pet birds could catch HPAI, too. Currently, no vaccine is authorized for animals in the U.S.

• #2 Avian Influenza (Bird Flu) | Erie County Department of Health (ECDOH)

  https://www3.erie.gov/health/avian-influenza-bird-flu

  Avian influenza A(H7N9) virus, highly pathogenic avian influenza (HPAI) A(H5N1), and A(H5N6) viruses have been responsible for most human illness from avian influenza viruses reported worldwide to date, including the most serious illnesses with high mortality (death). […] The spread of bird flu viruses from one infected person to a close contact is very rare, and when it has happened, it has only spread to a few people. However, because of the possibility that bird flu viruses could change and gain the ability to spread easily between people, monitoring for human infection and person-to-person spread is extremely important for public health.

• #2 Avian Influenza H5N1 (Bird Flu)

  https://www.healthhub.sg/a-z/diseases-and-conditions/topics_avian_flu_h5n1

  Avian influenza, also known as bird flu, is an infectious disease in birds caused by type A of the influenza virus. […] Domestic poultry, including chickens and turkeys, are particularly vulnerable to this rapidly fatal influenza. […] Birds infected by this type A influenza virus have a spectrum of symptoms, ranging from mild illness to a highly contagious and rapidly fatal disease resulting in severe epidemics, which are characterised by sudden onset, severe illness and rapid death. […] Influenza A (H5N1) virus, also called H5N1 virus, is a subtype of the influenza A virus that mainly affects birds and is deadly to them. […] The primary mode of transmission in human cases of avian influenza virus infection is from bird to human through direct or close contact with infected birds or contaminated surfaces. […] To date, the World Health Organisation (WHO) has stated that there is no evidence of sustained human-to-human transmission.

• #2 What Causes Bird Flu Virus Infections in Humans | Bird Flu | CDC

  https://www.cdc.gov/bird-flu/virus-transmission/avian-in-humans.html

  The spread of bird flu viruses from one infected person to a close contact is very rare, and when it has happened, it has only spread to a few people. […] However, because of the possibility that bird flu viruses could change and gain the ability to spread easily between people, monitoring for human infection and person-to-person spread is extremely important for public health.

• #2 Bird flu

  https://www.nhs.uk/conditions/bird-flu/

  Bird flu, or avian flu, is an infectious type of influenza that spreads among birds. In rare cases, it can affect humans. […] There are lots of different strains of bird flu virus. Most of them don’t infect humans. But there are 4 strains that have caused concern in recent years: H5N1 (since 1997), H7N9 (since 2013), H5N6 (since 2014), H5N8 (since 2016). […] Although H5N1, H7N9 and H5N6 don’t infect people easily and aren’t usually spread from human to human, several people have been infected around the world, leading to a number of deaths. […] In February 2021 H5N8 was found to have infected a small number of people for the first time, in Russia. […] Bird flu is spread by close contact with an infected bird (dead or alive). […] You can’t catch bird flu through eating fully cooked poultry or eggs, even in areas with an outbreak of bird flu.

• #2 Investigation of Avian Influenza A (H5N1) Virus in Dairy Cattle | FDA

  https://www.fda.gov/food/alerts-advisories-safety-information/investigation-avian-influenza-h5n1-virus-dairy-cattle

  The FDA continues to recommend that dairy producers monitor herds for H5N1 infection by enrolling in USDA or state testing programs. […] Research to date has demonstrated heating raw milk at 54C (130F) for at least 15 minutes or 60C (140F) for at least 10 seconds inactivates H5N1 in raw milk. […] The FDA has engaged in research and other efforts with industry, federal, and state partners to ensure the continued effectiveness of the federal-state milk safety system. […] Pasteurization kills harmful bacteria and viruses by heating milk to a specific temperature over time. Even if the virus is detected in raw milk, the current pasteurization process (HTST High Temperature, Short Time) will inactivate the virus. […] The FDA continues to advise strongly against the consumption of raw milk and recommends that industry does not manufacture or sell raw milk or raw milk products.

• #2 Bird Flu | Influenza A | Avian Flu | MedlinePlus

  https://medlineplus.gov/birdflu.html

  Birds, just like people, can get the flu. Another name for bird flu is avian influenza. The viruses that cause bird flu normally only infect birds, including chickens, other poultry, and wild birds such as ducks. But sometimes the viruses can infect other animals and, in rare cases, people. […] A few types of these viruses have caused most of the infections in people. They are the H5N1, H7N9, and H5N6 viruses. These infections in people have mainly been in Asia, Africa, Europe, the Pacific, and the Near East. Although it’s very rare, there have also been some infections in people in the United States. […] Bird flu can also infect many other animals, including some dogs, cats, certain wild and zoo animals, and livestock such as cattle. These animals can then spread the flu to people. […] Certain people may be more likely to get bird flu, including poultry workers, animal handlers, wildlife biologists, disease control workers, research laboratory workers, veterinarians, and people who travel to countries where bird flu is present.

• #2 H5N1 Avian Influenza (Bird Flu) From Dairy Cows – Your Questions, Answered | EBSCO

  https://www.ebsco.com/blogs/health-notes/h5n1-avian-influenza-bird-flu-dairy-cows-your-questions-answered

  Cases of H5N1 avian influenza virus have been reported in the United States in 2024. […] All cases are presumed to have acquired bird flu from infected dairy cows. […] The H5N1 avian influenza virus causing infections in dairy farm workers isn’t new. This strain of bird flu was first detected in humans in Asia in the 1990s and has continued to circulate among birds since then, causing occasional spillover cases in humans. […] Cows are an intermediary host, meaning that they are getting infected from birds (possibly by consuming grasses contaminated with bird feces). This is the first time that H5N1 bird flu has ever been detected in cows, and currently 168 dairy farms in the United States have reported positive H5N1 testing in their herds. […] The cases of H5N1 infection in dairy farm workers are associated with close contact with infected cows and it is thought that they may have acquired the infection during the milking process.

• #2 Avian Influenza – Overview | Occupational Safety and Health Administration

  http://www.osha.gov/avian-flu

  People should avoid unprotected exposure to dead animals/birds, animal waste, bedding, raw milk/uncooked animal products, or materials touched by, or close to animals with suspected or confirmed avian influenza. Workers who have unprotected exposure (no gloves or other personal protective equipment) with infected animals or their products (e.g. raw milk, raw cheeses, raw eggs) are at risk of infection.

• #2 Investigation of Avian Influenza A (H5N1) Virus in Dairy Cattle | FDA

  https://www.fda.gov/food/alerts-advisories-safety-information/investigation-avian-influenza-h5n1-virus-dairy-cattle

  The U.S. Department of Agriculture (USDA), the U.S. Food and Drug Administration (FDA), and the Centers for Disease Control and Prevention (CDC), along with state partners, continue to investigate an outbreak of Avian Influenza A (H5N1) impacting poultry, dairy cows, and people in multiple states. […] The FDA has sampled a total of 464 pasteurized dairy products, including milk, cheese, butter, and ice cream, all were negative for viable H5N1. In addition, multiple research studies have confirmed that pasteurization inactivates the virus. […] Research Results from Cornell University Suggest that the Aging Process Alone May Not Be Effective in Eliminating Viable H5N1 in Raw Milk Cheese. […] The FDA is confident that pasteurization is effective at inactivating H5N1, and that the commercial, pasteurized milk supply is safe.

• #2 Ask an Expert: What is Bird Flu, And Why Is It Such a Big Deal? | Cal Poly

  https://www.calpoly.edu/news/ask-expert-what-bird-flu-and-why-it-such-big-deal

  Declaring a state of emergency doesn’t mean there’s imminent danger of the virus crossing over into the human population and causing dangerous disease. […] Influenza viruses in general including this one are adept at mutating easily and quickly to avoid being neutralized by the immune system. The virus maintains its presence in nature by constantly being ahead of a population’s immune recognition capabilities. […] One of the scenarios where influenza viruses can be aided in mutating is when different strains of influenza mingle inside a host. That can facilitate viruses mixing genes and changing their surface proteins to the point where a new strain develops. These kinds of mixtures are thought to be how a newly-assembled influenza virus can become highly pathogenic and begin infecting other species.

• #2

  https://www.who.int/news-room/fact-sheets/detail/influenza-(avian-and-other-zoonotic)

  Human infections with avian and other zoonotic influenza viruses, though rare, have been reported sporadically. […] Current zoonotic influenza viruses have not demonstrated sustained person-to-person transmission. […] Whether currently circulating avian, swine and other influenza viruses will result in a future pandemic is unknown. […] The case fatality rate for A(H5) and A(H7N9) subtype virus infections among humans is higher than that of seasonal influenza infections. […] Influenza viruses are impossible to eradicate and zoonotic infections will continue to occur.

• #2 Bird Flu: Symptoms, Outbreak, Causes, Vaccine & Survival

  https://www.emedicinehealth.com/bird_flu/article_em.htm

  Bird flu is caused by a type of influenza A virus (for example, H5N1 and H7N9). […] If avian influenza mutated to be able to spread easily among people, it would likely cause a serious pandemic. […] Humans may get bird flu from contact with infected birds (chicken, for example) or their droppings or surfaces with infected droppings. […] However, if the highly pathogenic strains of bird flu (H5N1, H7N9) mutate to allow them to be easily transmitted from human to human, investigators are concerned that a lethal pandemic could occur in humans. […] The prognosis (outcomes) for bird flu continues to be poor with the death rate reaching about 60% with the N7H9 strain of bird flu, there is reason to believe it, too, could have a high death rate in future outbreaks.

• #2 H5N1 bird flu: Questions patients may have and how to answer | American Medical Association

  https://www.ama-assn.org/delivering-care/public-health/h5n1-bird-flu-questions-patients-may-have-and-how-answer

  Antiviral treatment works best when started early after symptoms begin. Antivirals can also be given soon after unprotected exposure to prevent infection and illness. […] There are H5 candidate vaccine viruses that could be used to produce a vaccine. According to the U.S. Department of Health and Human Services assistant secretary for preparedness and response, officials are moving ahead with a plan to produce 4.8 million doses of H5N1 avian flu vaccine for pandemic preparedness. […] Testing for the flu typically declines over the summer, but the CDC is working on a plan for enhanced nationwide monitoring to ensure that even rare cases of A(H5N1) virus in the community are detected.

• #2

  https://www.ncid.sg/Health-Professionals/Diseases-and-Conditions/Pages/Avian-Influenza.aspx

  In the 2004 outbreaks involving H5N1 subtype in Thailand and Vietnam, human cases were associated with severe respiratory disease and high mortality. […] Almost all human cases had antecedent avian exposure during a coincident avian influenza outbreak among chickens. […] Oseltamivir remains the primary recommended antiviral therapy. […] Oseltamivir resistance can emerge during therapy for avian H5N1 and may be associated with clinical deterioration. […] Surveillance of affected flocks and culling (killing) of sick and exposed birds are the most effective methods of controlling an epidemic.

• #2 Bird Flu | Influenza A | Avian Flu | MedlinePlus

  https://medlineplus.gov/birdflu.html

  Bird flu is treated with antiviral medicines. It’s important to get them as soon as possible. The medicines may make your illness less severe. […] There is currently no vaccine available to the public. The government has developed a virus that is similar to some H5N1 viruses. The virus could be used to produce a vaccine for people, if needed. […] Bird Flu in Animals and People: Causes and How It Spreads (Centers for Disease Control and Prevention) […] What Causes Bird Flu Virus Infections in Humans (Centers for Disease Control and Prevention) […] Avian Influenza in Birds: Causes and How It Spreads (Centers for Disease Control and Prevention)

• #2 Bird Flu: Symptoms, Causes, and Risk Factors

  https://www.healthline.com/health/avian-influenza

  Bird flu, also called avian influenza, is a viral infection that can infect not only birds, but also humans and other animals. Most forms of the virus are restricted to birds. […] H5N1 is the most common form of bird flu. Its deadly to birds and can easily affect humans and other animals that come in contact with a carrier. According to the World Health Organization, H5N1 was first discovered in humans in 1997 and has killed nearly 60 percent of those infected. […] Although there are several types of bird flu, H5N1 was the first avian influenza virus to infect humans. The first infection occurred in Hong Kong in 1997. The outbreak was linked to handling infected poultry. […] H5N1 occurs naturally in wild waterfowl, but it can spread easily to domestic poultry. The disease is transmitted to humans through contact with infected bird feces, nasal secretions, or secretions from the mouth or eyes.

• #2 Avian influenza

  https://tephi.texas.gov/training/selected-outbreaks/avianinfluenza

  Influenza A is an RNA virus, and like other RNA viruses, such as SARS-CoV-2, it mutates or changes easily and can obtain new characteristics. […] The virus currently infecting large numbers of both wild birds and domestic poultry is influenza A subtype H5N1. This influenza A found in birds commonly referred to as avian influenza is a highly pathogenic strain in birds, which means it causes high rates of death when birds are infected; therefore, it is often referred to as highly pathogenic avian influenza (HPAI). […] Since 1997, more than 900 human cases of influenza A (H5N1) that spilled over from birds have been reported in 23 countries, with more than half of these cases resulting in death. […] The World Health Organization and the US Centers for Disease Control and Prevention have stated that at this time, the avian flu risk to the general public remains low.

• #2 Avian Influenza – WOAH – World Organisation for Animal Health

  https://www.woah.org/en/disease/avian-influenza/

  Avian influenza, also known as bird flu, is a highly contagious viral disease that affects both domestic and wild birds. This complex disease is caused by viruses divided into multiple subtypes (i.e. H5N1, H5N3, H5N8 etc.) whose genetic characteristics rapidly evolve. […] The many strains of avian influenza viruses can generally be classified into two categories according to the severity of the disease in poultry: low pathogenicity avian influenza (LPAI) that typically causes little or no clinical signs; high pathogenicity avian influenza (HPAI) that can cause severe clinical signs and possible high mortality rates. […] While it is likely that international trade, farming practices and migratory wild birds have contributed to the spread of avian influenza, the current wide range of avian influenza subtypes circulating shows an ever-evolving complexity in both virus genetics and spatiotemporal distribution. This might be explained by multiple reassortments with low pathogenicity viruses circulating in wild birds. […] The transmission of avian influenza from birds to humans is rare and usually occurs when there is close contact with infected birds or heavily contaminated environments. […] The risk of transmission of avian influenza from a sick cat to a human is currently very low or negligible.

• #2 Avian Influenza (Bird Flu) Fact Sheet | Cornell University College of Veterinary Medicine

  https://www.vet.cornell.edu/highly-pathogenic-avian-influenza-bird-flu-resource-center/avian-influenza-bird-flu-fact-sheet

  This finding suggests that the outbreak in Nevada did not result from contact with an infected cow or contaminated farm equipment, but rather resulted from a new introduction into cattle from wild birds. […] While this new genetic variation (genotype D1.1) does not in and of itself greatly change the risk to cattle or human health, it shows the risk of new introductions from birds into dairy operations. […] Avian influenza can be divided into two categories: highly pathogenic (HPAI) or low pathogenic (LPAI) strains. […] Avian influenza is categorized as HPAI depending on the severity of infection in domestic poultry, such as chickens and turkeys. […] Technically, a strain is defined as HPAI if it kills at least 75% of 4- to 6-week-old chickens within 10 days of infection. […] Practically, however, classification is based on whether there is systemic infection – infection that spreads beyond the respiratory tract – or if infection remains local to the respiratory system. […] The H5 and H7 subtypes are the most common causes of HPAI, and are also the subtypes that are most likely to infect humans. The current outbreak of HPAI is due to an H5N1 subtype.

• #2 Influenza A virus subtype H5N1 – Wikipedia

  https://en.wikipedia.org/wiki/Influenza_A_virus_subtype_H5N1

  All subtypes of avian Influenza A have potential to cross the species barrier, with H5N1 and H7N9 considered the biggest threats. […] The avian influenza hemagglutinin prefers to bind to alpha-2,3 sialic acid receptors, while the human influenza hemagglutinin prefers to bind to alpha-2,6 sialic acid receptors. This means that when the H5N1 strain infects humans, it will replicate in the lower respiratory tract (where alpha-2,3 sialic acid receptors are more plentiful in humans) and consequently cause viral pneumonia. […] The H5N1 avian flu variant had first been identified in cattle around March 25, 2024. […] A wide range of other animals have been affected by avian flu, generally due to eating birds which had been infected.

• #2 Bird Flu Is Raising Red Flags Among Health Officials | Johns Hopkins | Bloomberg School of Public Health

  https://publichealth.jhu.edu/2025/bird-flu-is-raising-red-flags-among-health-officials

  H5N1 is a dynamic virus that poses an increasing threat in terms of spillover and pandemic potential. […] To make matters worse, samples taken from the individual suggest that the virus mutated within the patient after infection meaning it had begun to adapt to infect humans better raising new questions about H5N1’s pandemic potential. […] H5N1 is a very dynamic virus. There’s lots of versions of it circulating in lots of different animals and birds, and it’s continuing to pose a greater and greater threat in terms of spillover and leading to a pandemic. […] The critical thing is understanding whether the virus that’s in dairy cows right now will pick up mutations that will help it to be more transmissible in mammals. […] If the virus changes the way it transmits and becomes a respiratory pathogen among dairy cows, that would be another sign that this virus is changing and posing more of a risk to the human population.

• #2 Avian influenza | Poultry diseases | Animal diseases | Biosecurity | Agriculture Victoria

  https://agriculture.vic.gov.au/biosecurity/animal-diseases/poultry-diseases/avian-influenza-bird-flu

  With the emergence of H5 bird flu internationally, many animal species have become infected following close contact with infected birds or contaminated environments. […] Ongoing outbreaks of H5 bird flu globally have increased the level of risk to Australia for incursions of HPAI viruses of global concern. Occasional outbreaks of internationally notifiable high pathogenicity avian influenza (non-H5N1) and of low pathogenicity avian influenza do occur on poultry farms in Australia, such as the H7 outbreaks in 2020, 2024 and 2025. […] Procedures for responding to outbreaks generally include: euthanasia of infected and in-contact poultry (depopulation), decontamination, strict quarantine, movement controls to prevent the spread of infection, tracing and surveillance to locate the extent of infection.

• #2 Bird Flu H5N1 Causes, Symptoms and Treatments | Froedtert & MCW

  https://www.froedtert.com/infectious-diseases/bird-flu

  Bird flu, also known as avian influenza, is an infectious disease caused by a virus that mainly affects birds but can also infect humans. The disease comes from influenza A viruses, which have several subtypes. The subtypes fall into categories based on the protein composition on the virus’s surface, namely, hemagglutinin (H) and neuraminidase (N) as seen in names such as H5N1 and H7N9. […] Bird flu refers to a specific Type A flu virus, H5N1, which currently spreads easily among birds, but can sometimes spread to other animals and humans. […] The virus can survive in the environment especially in water and on surfaces for long periods. […] Migratory birds play a significant role in spreading the virus during seasonal migration, introducing it to areas that have not been affected by the virus before. […] Research is ongoing to develop vaccines for humans that can offer a stronger defense against bird flu. Developing a vaccine is challenging due to the virus’s ability to change, requiring constant updates to vaccine formulations.

• #3 Avian Influenza – WOAH – World Organisation for Animal Health

  https://www.woah.org/en/disease/avian-influenza/

  Avian influenza, also known as bird flu, is a highly contagious viral disease that affects both domestic and wild birds. This complex disease is caused by viruses divided into multiple subtypes (i.e. H5N1, H5N3, H5N8 etc.) whose genetic characteristics rapidly evolve. […] The many strains of avian influenza viruses can generally be classified into two categories according to the severity of the disease in poultry: low pathogenicity avian influenza (LPAI) that typically causes little or no clinical signs; high pathogenicity avian influenza (HPAI) that can cause severe clinical signs and possible high mortality rates. […] While it is likely that international trade, farming practices and migratory wild birds have contributed to the spread of avian influenza, the current wide range of avian influenza subtypes circulating shows an ever-evolving complexity in both virus genetics and spatiotemporal distribution. This might be explained by multiple reassortments with low pathogenicity viruses circulating in wild birds. […] The transmission of avian influenza from birds to humans is rare and usually occurs when there is close contact with infected birds or heavily contaminated environments. […] The risk of transmission of avian influenza from a sick cat to a human is currently very low or negligible.

• #3 Pathology, Molecular Biology, and Pathogenesis of Avian Influenza A (H5N1) Infection in Humans

  https://pmc.ncbi.nlm.nih.gov/articles/PMC2329826/

  Various factors are thought to be involved in the pathogenesis of H5N1 influenza, and a combination of these factors most likely determines the extent of tissue injury and disease outcome. […] The role of dysregulation of cytokines and chemokines has been studied extensively and may be one of the key mechanisms in the pathogenesis of H5N1 influenza, in addition to injury resulting from viral replication. […] Up-regulation of functional TRAIL in macrophages infected with the H5N1 virus may be another important factor in the pathogenesis of H5N1 influenza virus infection. […] H5N1 viral replication appears to be prolonged with high levels of viral RNA, and the virus may disseminate to extra-pulmonary organs. […] The NS gene of H5N1 viruses may also account for up-regulation of cytokines and chemokines. […] The presence of glutamic acid at position 92 of NS1 appeared to be a prerequisite for the resistance to antiviral cytokines. […] In fact virulence appears to be a polygenic trait with several genes co-operating together.

• #3 What makes the bird flu virus so unusual? – News Bureau

  https://news.illinois.edu/what-makes-the-bird-flu-virus-so-unusual/

  The H5N1 virus attacks specific body systems in each species and behaves very differently in each depending on which body systems are involved, causing widespread death in some animals while barely affecting others, says University of Illinois Urbana-Champaign veterinary clinical medicine professor Dr. Jim Lowe. […] For influenza A viruses like H5N1, the key receptor is a sialic acid receptor. Humans primarily have one type, while birds have another. Different species have varying mixes of SA receptors, which influences disease transmission. […] Initially, we believed cows lacked these receptors entirely. While they dont have them in their respiratory tract, they do in the udder allowing H5N1 infection. […] Weve also seen H5N1 infect marine mammals like seals which have birdlike SA receptors in their respiratory tracts, making them highly susceptible.

• #3 Avian influenza – Wikipedia

  https://en.wikipedia.org/wiki/Avian_influenza

  Avian influenza, also known as avian flu or bird flu, is a disease caused by the influenza A virus, which primarily affects birds but can sometimes affect mammals including humans. Wild aquatic birds are the primary host of the influenza A virus, which is enzootic (continually present) in many bird populations. […] Influenza A virus is shed in the saliva, mucus, and feces of infected birds; other infected animals may shed bird flu viruses in respiratory secretions and other body fluids (e.g., cow milk). The virus can spread rapidly through poultry flocks and among wild birds. A particularly virulent strain, influenza A virus subtype H5N1 (A/H5N1) has the potential to decimate domesticated poultry stocks and an estimated half a billion farmed birds have been slaughtered in efforts to contain the virus.

• #3 Avian Influenza (Bird Flu) | Erie County Department of Health (ECDOH)

  https://www3.erie.gov/health/avian-influenza-bird-flu

  Avian influenza A(H7N9) virus, highly pathogenic avian influenza (HPAI) A(H5N1), and A(H5N6) viruses have been responsible for most human illness from avian influenza viruses reported worldwide to date, including the most serious illnesses with high mortality (death). […] The spread of bird flu viruses from one infected person to a close contact is very rare, and when it has happened, it has only spread to a few people. However, because of the possibility that bird flu viruses could change and gain the ability to spread easily between people, monitoring for human infection and person-to-person spread is extremely important for public health.

• #3 H5N1 bird flu: Questions patients may have and how to answer | American Medical Association

  https://www.ama-assn.org/delivering-care/public-health/h5n1-bird-flu-questions-patients-may-have-and-how-answer

  Antiviral treatment works best when started early after symptoms begin. Antivirals can also be given soon after unprotected exposure to prevent infection and illness. […] There are H5 candidate vaccine viruses that could be used to produce a vaccine. According to the U.S. Department of Health and Human Services assistant secretary for preparedness and response, officials are moving ahead with a plan to produce 4.8 million doses of H5N1 avian flu vaccine for pandemic preparedness. […] Testing for the flu typically declines over the summer, but the CDC is working on a plan for enhanced nationwide monitoring to ensure that even rare cases of A(H5N1) virus in the community are detected.

• #3 Avian Influenza (Bird Flu) Fact Sheet | Cornell University College of Veterinary Medicine

  https://www.vet.cornell.edu/highly-pathogenic-avian-influenza-bird-flu-resource-center/avian-influenza-bird-flu-fact-sheet

  This finding suggests that the outbreak in Nevada did not result from contact with an infected cow or contaminated farm equipment, but rather resulted from a new introduction into cattle from wild birds. […] While this new genetic variation (genotype D1.1) does not in and of itself greatly change the risk to cattle or human health, it shows the risk of new introductions from birds into dairy operations. […] Avian influenza can be divided into two categories: highly pathogenic (HPAI) or low pathogenic (LPAI) strains. […] Avian influenza is categorized as HPAI depending on the severity of infection in domestic poultry, such as chickens and turkeys. […] Technically, a strain is defined as HPAI if it kills at least 75% of 4- to 6-week-old chickens within 10 days of infection. […] Practically, however, classification is based on whether there is systemic infection – infection that spreads beyond the respiratory tract – or if infection remains local to the respiratory system. […] The H5 and H7 subtypes are the most common causes of HPAI, and are also the subtypes that are most likely to infect humans. The current outbreak of HPAI is due to an H5N1 subtype.

• #4 Pathology, Molecular Biology, and Pathogenesis of Avian Influenza A (H5N1) Infection in Humans

  https://pmc.ncbi.nlm.nih.gov/articles/PMC2329826/

  Various factors are thought to be involved in the pathogenesis of H5N1 influenza, and a combination of these factors most likely determines the extent of tissue injury and disease outcome. […] The role of dysregulation of cytokines and chemokines has been studied extensively and may be one of the key mechanisms in the pathogenesis of H5N1 influenza, in addition to injury resulting from viral replication. […] Up-regulation of functional TRAIL in macrophages infected with the H5N1 virus may be another important factor in the pathogenesis of H5N1 influenza virus infection. […] H5N1 viral replication appears to be prolonged with high levels of viral RNA, and the virus may disseminate to extra-pulmonary organs. […] The NS gene of H5N1 viruses may also account for up-regulation of cytokines and chemokines. […] The presence of glutamic acid at position 92 of NS1 appeared to be a prerequisite for the resistance to antiviral cytokines. […] In fact virulence appears to be a polygenic trait with several genes co-operating together.

Zobacz więcej