2020 and prior Genetic reassortment of several influenza A strains culminates in the emergence of a highly pathogenic H5N1 subtype bearing the clade 2.3.4.4b hemagglutinin (HA) gene. It was later detected in December in Estonia in wild foxes. About 8,000 cranes died in Israel. Over 1,700
great cormorants died from H5N1 in the
Baltic Sea in the summers of 2021 and 2022.
2022 In January 2022, an infection in an eighty-year-old man who raises ducks in England was reported. The virus continued to spread further, infecting additional species of mammals. In October, a mink farm in northwest Spain was affected. A human case of H5N1 was reported in the U.S. in April, "though this detection may have been the result of contamination of the nasal passages with the virus rather than actual infection." In September, Spain reported a human case; this was followed by a second case in November, in a person who worked at the same poultry farm as the first. Both were asymptomatic. In November, China reported a human case, infected due to contact with poultry. The case died from their infection.
2023 Antarctic islands H5N1 was first detected in the islands of the Antarctic region in October 2023, via a
brown skua on Bird Island, near
South Georgia. Within several months, hundreds of
elephant seals were found dead, as well as
fur seals,
kelp gulls, 77 brown skuas, 38
gentoo penguins, and 58
snowy albatrosses.
Arctic In December 2023, conservation officials confirmed that a
polar bear had died of H5N1 near Alaska's northernmost city,
Utqiagvik.
Canada On 1 April 2023, a domestic dog in
Oshawa tested positive for H5N1.
Cambodia In February 2023, Cambodia reported the death of a girl due to H5N1 infection after developing symptoms on 16 February. The girl's father also tested positive for the virus. The
World Health Organization (WHO) described the situation as "worrying" and urged "heightened vigilance". Further sequencing determined that at least one of the two cases was from an older H5N1 clade, 2.3.2.1c, which had circulated as a common H5N1 strain in Cambodia for many years, rather than the more recent clade 2.3.4.4b, which had caused mass poultry deaths since 2020. This older clade had jumped to humans in the past yet hadn't previously resulted in any known human-to-human transmission. On 1 March 2023, as Taiwan raised its travel alert for Cambodia, the WHO and the U.S.
Center for Disease and Control and Prevention (CDC), in concert with Cambodian authorities, determined that both of the individuals had been infected through direct contact with poultry.
China On 4 February 2023, a 53-year-old patient was admitted to hospital with severe
pneumonia in Jiangsu. Genetic sequencing revealed that the H5N1 avian influenza infected in this case belonged to clade 2.3.4.4b. She had a co-infection of H5N1 and
SARS-CoV-2.
Hungary 10,000 cranes died of bird flu in Hungary. In March 2023, H5N1 was detected in
black-necked swan populations in
Carlos Anwandter Nature Sanctuary, Chile and Uruguay. In Uruguay the death of ten swans found in the locality of
Estación Tapia was attributed to flu. The patient survived but had to stay on a ventilator. The virus was determined to be in the 2.3.4.4b lineage. In September 2023, Uruguay reported upwards of 400 seals and sea lions found dead of H5N1 on the nation's Atlantic coastline and along the
River Plate. Between January and October 2023, at least 24,000
South American sea lions died from H5N1 flu, with the outbreak starting on the Pacific coast of Peru, moving down the coast to Chile and then up the Atlantic coast of Argentina. An outbreak of H5N1 killed 70% of
Southern elephant seal pups born in the 2023 breeding season. In surveyed areas of
Península Valdés, Argentina, seal mortality rates reached 96%. In February, scientists found H5N1 in 12
Antarctic skua seabirds carcasses on
Beak Island. Additional cases have also been found at
Hope Bay and on the
Devil and
Paulet islands. In March, scientists detected the virus in nine
Adélie penguins and one
Antarctic cormorant.
Australia In May 2024, H5N1 was detected for the first time in Australia after a human child who had returned to the country from India tested positive. The child was infected with the South Asian 2.3.2.1a clade of H5N1 and had severe symptoms but recovered.
India On 18 April 2024, H5N1 was detected in ducks in
Alappuzha district, Kerala. The
District Collector decided to initiate the process of culling domestic birds within a radius from the center of the outbreak. By 9 May 2024, district officials had culled 60,232 birds in Alappuzha. Farmers were compensated
₹100 per ducklings and chicks, ₹200 per older bird, and ₹5 per egg destroyed.
Canada In November 2024, a teenager from the
Vancouver region became infected with H5N1 avian influenza from an unknown source. Initially presenting with ocular symptoms, the patient later developed a serious pneumonia, indicating a novel progression of disease. The virus belongs to the 2.3.4.4b clade which has been circulating among poultry in British Columbia, related to virus carried by wild birds migrating along the
Pacific flyway.
China On 18 May, Chinese authorities confirm 275 cases of bird flu in dead
Pallas's gulls and other wild birds in two counties in
Qinghai province.
Southeast Asia A cluster of five human infections of H5N1 occurred in Cambodia in late January and early February; one patient died. All patients had recent contact with sick poultry. Genetic sequencing revealed that they were infected by clade 2.3.2.1c, a different
lineage from the 2.3.4.4b clade that is causing global outbreaks. A person in Vietnam died of H5N1 infection around the same time, clade unknown. In April 2024, the FAO reported that recent reassortment in the
Greater Mekong Subregion has produced viruses that carry internal genes from the 2.3.4.4b lineage but the H5 gene from the older 2.3.2.1c lineage. These viruses have been implicated in human cases. On 5 April, the Philippines reported a H5N1 outbreak on a poultry farm in
Leyte, which killed 4,475 birds. Earlier in the year, the Philippines Department of Agriculture temporarily banned poultry exports from several countries including Japan, Belgium, and France. On 6 July, it was reported that two Cambodian children became sick with H5N1 infections after handling dead chickens.
United States egg price index The US CDC continues to report "widespread" occurrence in wild birds, "sporadic outbreaks" in poultry flocks, and "sporadic infections" in mammals as of March 2024. As of 8 March 2024, the
United States Department of Agriculture's (USDA) Animal and Plant Health Inspection Service (APHIS) had recorded around
20 mammal species confirmed as being able to be infected by H5N1. Also in March 2024, H5N1 was confirmed to have infected farmed goats and cows in the USA. On 2 April, a dairy worker in Texas became infected, and strong indications of cow-to-cow spread were evident as cow herds in five different states became ill. A few days later, on 4 April, H5N1 was confirmed to have spread to several additional dairy herds in six US states, including Texas, along with Idaho, Kansas, New Mexico, Ohio and Michigan. Scientists deemed these to be either cow-to-cow transmission or
spillover from wild birds. On 11 April, H5N1 was found in dairy cattle herds in North Carolina and South Dakota. On 10 April, researchers found several cases of HPAI H5N1 in animals in New York City, including three
Canada geese, a
red-tailed hawk, a
peregrine falcon, and a chicken. Scientists have also found cases of H5N1 of clade 2.3.4.4b in
common bottlenose dolphins from Florida. On 26 April, the FDA reported the virus had spread to cow herds in nine states, including
Colorado, with one in five U.S. commercial milk samples testing positive for traces of bird flu. H5N1 was found to be present at high levels in the mammary glands of affected cows, and cats that consumed unpasteurized milk from symptomatic cows displayed a high mortality rate from a severe systemic influenza infection. More than half the cats on one farm died after drinking raw milk from infected cows. On 10 May, the
Biden administration announced it would provide nearly $200 million to help contain the current outbreak. The
US Department of Agriculture pledged $98 million at a split of $28,000 per dairy farm, while the
Department of Health and Human Services (HHS) will provide $101 million split between the
FDA and the
US Centers for Disease Control and Prevention (CDC). On 16 May, the US Department of Agriculture's
National Veterinary Services Laboratories confirmed positive tests for the virus in
alpacas on a farm in Idaho, who had to be culled. On 22 May, a farm worker in Michigan was infected with the bird flu due to their regular exposure to infected dairy cows. The person had mild symptoms and recovered. It was shown that H5N1 can persist on milking equipment, which provides a probable transmission route for cow-to-cow and cow-to-human spread. On 30 May, it was announced that a second Michigan farm worker from a different dairy farm had been diagnosed with bird flu after exhibiting respiratory symptoms. In early June, a flock of 4.2 million egg-laying chickens and a flock of 103,000 turkeys were infected in
Iowa. It was also that reported that HPAI H5N1 had spread to dairy herds in Iowa, as well as
Minnesota,
Wyoming and
Oklahoma, increasing the number of states with infected dairy herds to thirteen. As of 6 June, infected dairy cows in five states, South Dakota, Michigan, Texas, Ohio, and Colorado, had died from the H5N1 avian flu, with an estimated mortality rate of up to 10%. Beginning in late June, the USDA launched voluntary pilot programs to test bulk milk tanks on dairy farms in four states: Kansas, Nebraska, New Mexico, and Texas. Farmers who volunteer for the program were allowed to move their herds across state lines without additional testing if their bulk milk tanks were found negative for H5N1 for three consecutive weeks. By the end of July, it had become apparent that
Weld County, Colorado had become the centre of the unprecedented multi-species outbreak of H5N1 in the United States. Outbreaks in multiple large poultry facilities and intensive dairy farms led to ten human farm-worker cases being reported in and around the county. Research conducted in this region showed H5N1 as having the ability to replicate copiously in bovine mammary glands leading to multi-directional intra- and inter-species transmission between cows, humans, cats, birds and a raccoon. It was also shown that asymptomatic cows could spread the disease. In response, the Colorado authorities brought in mandatory milk tank testing (excluding
raw milk producers) and an on-line data tracker for human cases in the state. On 31 July, a study found 2 farmworkers who had not been tested for bird flu had antibodies against it. On 9 August, the
Colorado Department of Public Health reported bird flu in domestic cats, including indoor-only cats. In late August, H5N1 had spread to
dairy cow herds in California. On 22 August, the first person in the U.S. who didn't work with poultry or dairy cows was hospitalized with the H5 influenza virus. This person is also the 15th human case of H5 reported in the U.S. since 2022. In September 2024, the
CDC confirms that two dairy workers in California have contracted bird flu, marking the 15th and 16th human cases in this year's ongoing outbreak, which has impacted dairy cows nationwide. The cases occurred in
California's Central Valley, where over 50 herds have been affected since August. Both workers, who had contact with infected cattle, developed mild symptoms, including
conjunctivitis. The CDC confirmed the positive test results on Thursday, while state health officials noted that the workers were employed at separate farms, indicating the infections likely resulted from animal exposure rather than human transmission. In October 2024, a third farmworker in California has tested positive for bird flu, according to the state's health department, marking the 17th potential human case of H5N1 in the U.S. since March. Like the previous two cases, this farmworker had contact with infected dairy cattle, and investigators believe the transmission occurred from animals rather than between people. By late October, California had reported that 133 of its 1,100 dairy herds were infected, with a bovine mortality rate of around 15%. The business interests of the heavily corporatised dairy and livestock industries being prioritised over public health and animal welfare was stipulated as the main cause of the failure to control the novel outbreak. H5N1 was also detected in a pig in
Oregon, the first ever reported case in the USA. Meanwhile, by late November human cases of H5N1 in the USA increased to over fifty for the year with infections being reported in seven states. On 7 November, the CDC reported asymptomatic bird flu infection in 4 workers at dairy farms. The workers didn't recall ever being sick but had antibodies showing that they had been infected with bird flu. On 22 November, the CDC confirmed the first case of bird flu in a U.S. child, being the 55th case of bird flu in humans in the U.S. The child also tested positive for other common respiratory viruses.
New Scientist said that an H5N1 virus infecting a human could acquire all the abilities it needs to become a pandemic virus by swapping genes with a human virus infecting the same individual. In the last quarter of 2024, 20 million chickens were put down, causing an egg shortage in the following months. On 6 December, the USDA announced a new mandate to test the national milk supply for bird flu as part of efforts to combat the virus's spread among dairy herds. Beginning 16 December, entities handling raw milk, such as dairy processors, would collect and share samples with agricultural officials. The initiative initially targeted six states: California, Colorado, Michigan, Mississippi, Pennsylvania, and Oregon. Since March, over 700 dairy herds, predominantly in California, had already been affected, alongside 57 human cases of mild symptoms reported across the country. The USDA emphasized the program's role in swiftly identifying and controlling outbreaks, ensuring the safety of livestock and public health. The agency further noted that the mandate complemented rather than replaced an earlier April mandate requiring bird flu testing for milk-producing cows before interstate movement. On 18 December,
Centers for Disease Control and Prevention confirmed that a patient in Louisiana was hospitalized with a severe case of H5N1, as well as another case in Wisconsin. The Louisiana patient later died, becoming the first human fatality to H5N1 to occur in the USA. California governor
Gavin Newsom announced a state of emergency due to the rising cases of the bird flu. The following day, a report of a human case with the bird flu was confirmed in Texas.
2025 Cambodia In January, a 28-year-old man from
Kampong Cham province died from H5N1 avian flu infection after possibly consuming symptomatic chickens. In February, a second death from H5N1 occurred in a toddler who had played and slept near sick chickens. In March, a 3-year-old boy died from H5N1 after being exposed to and consuming infected chickens.
Germany Estimated 2,000 cranes died of bird flu. The
Friedrich Loeffler Institute (FLI) registered 15 outbreaks in poultry farms. The
German government culled over 500,000 birds in October as the FLI reported over 103 outbreaks, including 30 among
poultry battery farms, across the country.
India India reported a fatal human case of H5N1 in April.
Mexico Mexico reported its first human case of H5N1 infection in April. The patient, a 3 year old girl, died soon after.
United Kingdom The UK reported a human case of H5N1 avian influenza in late January which was detected in a poultry farm worker. An infected
sheep located on an outbreak affected poultry farm was reported in March. Similar to H5N1 in cows, the sheep displayed
mastitis and produced milk containing the virus. In November the progress of the outbreak in the UK was described as equal to that of 2022-2023, the previous season with largest outbreak; 50 cases had occurred so far on farms across the UK this season.
United States , New York in February 2025. On 6 January, the
Louisiana Department of Health reported the first confirmed bird flu-related death in a human the United States. The victim, an unidentified Louisiana man, had previously been reported sick with the virus in December after being exposed to a combination of infected backyard chickens and wild birds. The man was reported to be over 65 and had underlying health conditions. On 12 February, Ohio confirmed their first case, being an adult male, which was then followed by
Wyoming Department of Health reporting the first case of bird flu in their state two days later on 14 February, which was a woman. ==See also==