2020–2024 H5N1 outbreak

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Since 2020, global cases of avian influenza subtype H5N1 have been rising, with cases reported from every continent as of February 2023 except for Australia and Antarctica.[1][2][3][4] In late 2023, H5N1 was discovered in the Antarctic for the first time, raising fears of imminent spread throughout the region, potentially leading to a "catastrophic breeding failure" among animals that had not previously been exposed to avian influenza viruses.[5] The virus involved in the outbreak is classified in H5 clade 2.3.4.4b.[6][7]

Timeline[edit]

Urner Barry Egg Index

Origin[edit]

H5N6 and H5N8 viruses with the H5-2.3.4.4b hemagglutinin (HA) gene became prominent globally among poultry in 2018–2020.[7] In 2020, reassortment (genetic "swapping") between these H5-2.3.4.4b poultry viruses and N1 wild bird viruses led to the emergence of a H5N1 with a H5-2.3.4.4b gene. The virus then spread across Europe, detected there in autumn, before spreading to Africa and Asia.[1]

2021[edit]

In May 2021, H5N1 was detected in wild red foxes in the Netherlands.[8] It was later detected in December in Estonia in wild foxes.[1][9]

2022[edit]

In January 2022, an infection in an eighty-year-old man was reported, who raised ducks in England.[1] Also in January, infections were reported from the United States in wild birds.[1] In February, infections were reported from commercial poultry centres in the U.S., and Peru reported infections in sea lions.[1][10] A human case of H5N1 was reported in the U.S. in April.[1][11] The virus continued to spread further, infecting additional species of mammals. In September, Spain reported a human case; this was followed by a second case, in a person who worked at the same poultry farm as the first.[1][12] In November, China reported a human case, infected due to contact with poultry. The case died from their infection.[1]

2023[edit]

Antarctic islands[edit]

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 and further brown skua.[13]

Arctic[edit]

In December 2023, conservation officials confirmed that a polar bear had died of H5N1 near Alaska's northernmost city, Utqiagvik.[13]

Cambodia[edit]

In February 2023, Cambodia reported the death of a girl due to H5N1 infection after developing symptoms on 16 February.[14][15] The girl's father also tested positive for the virus. The World Health Organization (WHO) described the situation as "worrying" and urged "heightened vigilance".[16][17][18] 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.[19]

On March 1, 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.[20][21]

South America[edit]

In late February 2023, Argentina confirmed a case of H5N1 in industrial poultry, in the Rio Negro province. Avian product exports were suspended as a result.[22]

In March 2023, H5N1 was detected in black-necked swan populations in Carlos Anwandter Nature Sanctuary, Chile and Uruguay.[23][24] In Uruguay the death of ten swans found in the locality of Estación Tapia was attributed to flu.[24] Previously in Uruguay ten hens had died because of the flu in El Monarca, Montevideo.[24]

In late March 2023, Chile detected H5N1 in a 53 year-old man who had severe symptoms.[25]

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.[26]

According to a 2024 paper, a large outbreak of H5N1 killed 70% of elephant seal pups born in the 2023 breeding season. In surveyed areas of Península Valdés, Argentina, seal mortality rates exceed 96%.[6] A February 2024 article reports that the outbreak in South America has, since 2022, killed at least 600,000 wild birds and 50,000 mammals.[6]

Canada[edit]

On April 1 a domestic dog in Ottawa, Canada was tested positive for H5N1.[27]

Brazil[edit]

On May 22, Brazil declared an 180-day "animal health emergency" in response to eight cases of H5N1 found in wild birds. Although Brazil's major poultry-producing regions are in the country's south and the infections were found in Espirito Santo state and Rio de Janeiro state, Brazil, as the world's largest exporter of chicken meat, created an emergency operations center to plan for and mitigate potential further spread of H5N1.[28]

2024[edit]

Southeast Asia[edit]

A cluster of five human infections of H5N1 occurred in Cambodia in late January and early February. All patients had recent contact with sick poultry. One patient died. Sequencing of two of the patients indicate that they were infected by clade 2.3.2.1c, which is not the same same as the 2.3.4.4b clade virus that is causing global outbreaks in the US and beyond.[29] A person in Vietnam died of H5N1 infection around the same time.[30]

On April 5, 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.[31]

USA[edit]

The US CDC continues to report "widespread" occurrence in wild birds, "sporadic outbreaks" in poultry flocks, and "sporadic infections" as of March 2024.[32] As of March 8, 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.[33] Also in March 2024, H5N1 was confirmed to have infected farmed goats and cows in the USA.[34]

On April 2, 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.[35] A few days later on April 4, 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 have deemed these to be either cow-to-cow transmission or spillover from wild birds.[36][37][38]

Antarctica[edit]

H5N1 was detected in dead birds on the Antarctic mainland for the first time in February 2024.[39]

Control[edit]

H5-2.3.4.4b can be prevented by vaccination in chickens. The H5-Re14 (2.3.4.4b) strain used in updated vaccines since 2022 is a reasonably good match for the new virus.[40]

See also[edit]

References[edit]

  1. ^ a b c d e f g h i "Highlights in the History of Avian Influenza (Bird Flu) Timeline – 2020-2023 | Avian Influenza (Flu)". www.cdc.gov. 2023-02-24. Retrieved 2023-02-24.
  2. ^ "A global bird flu outbreak is now so bad, many countries are considering vaccination". ABC News. 2023-02-16. Retrieved 2023-02-24.
  3. ^ Worden-Sapper, Emma; Sawyer, Sara; Wu, Sharon. "As bird flu continues to spread in the US and worldwide, what's the risk that it could start a human pandemic? 4 questions answered". The Conversation. Retrieved 2023-03-30.
  4. ^ Docter-Loeb, Hannah. "Vaccine Makers Are Preparing for Bird Flu". Scientific American. Retrieved 2023-03-30.
  5. ^ Weston, Phoebe (24 October 2023). "'Catastrophic': bird flu reaches Antarctic for the first time". The Guardian. Archived from the original on 29 October 2023. Retrieved 30 October 2023.
  6. ^ a b c Kerlin, Katherine E. (28 February 2024). "Avian Influenza Virus Is Adapting to Spread to Marine Mammals". UC Davis.
  7. ^ a b "Emergence and Evolution of H5N1 Bird Flu | Avian Influenza (Flu)". www.cdc.gov. 6 June 2023.
  8. ^ Rijks, Jolianne M.; Hesselink, Hanna; Lollinga, Pim; Wesselman, Renee; Prins, Pier; Weesendorp, Eefke; Engelsma, Marc; Heutink, Rene; Harders, Frank; Kik, Marja; Rozendaal, Harry; van den Kerkhof, Hans; Beerens, Nancy (November 2021). "Highly Pathogenic Avian Influenza A(H5N1) Virus in Wild Red Foxes, the Netherlands, 2021". Emerging Infectious Diseases. 27 (11): 2960–2962. doi:10.3201/eid2711.211281. ISSN 1080-6059. PMC 8544991. PMID 34670656.
  9. ^ European Food Safety Authority, European Centre for Disease Prevention, Control, European Union Reference Laboratory for Avian Influenza; Adlhoch C, Fusaro A, Gonzales JL, Kuiken T, Marangon S, Niqueux É, Staubach C, Terregino C, Aznar I, Muñoz Guajardo I, Baldinelli F. Avian influenza overview September - December 2021. EFSA J. 2021 Dec 23;19(12):e07108. doi: 10.2903/j.efsa.2021.7108. PMID 34987626; PMCID: PMC8698678.
  10. ^ Collyns, Dan (2023-03-21). "First birds, now mammals: how H5N1 is killing thousands of sea lions in Peru". The Guardian. ISSN 0261-3077. Retrieved 2023-03-30.
  11. ^ "CDC Newsroom". CDC. 2016-01-01. Retrieved 2023-02-24.
  12. ^ "Avian Influenza A (H5N1) – Spain". www.who.int. Retrieved 2023-02-24.
  13. ^ a b Weston, Phoebe (2 January 2024). "Polar bear dies from bird flu as H5N1 spreads across globe". The Guardian. Archived from the original on 4 January 2024. Retrieved 4 January 2024.
  14. ^ "Bird flu death: What will happen next and is there a vaccine?". New Scientist. Retrieved 2023-02-24.
  15. ^ "Bird flu: 11-year-old girl in Cambodia dies after being infected". The Guardian. 2023-02-24. ISSN 0261-3077. Retrieved 2023-02-24.
  16. ^ Rigby, Jennifer (2023-02-24). "Bird flu situation 'worrying'; WHO working with Cambodia". Reuters. Retrieved 2023-02-24.
  17. ^ "H5N1: Cambodian girl dies in rare bird flu case". BBC News. 2023-02-24. Retrieved 2023-02-24.
  18. ^ "An 11-year-old girl has died from bird flu in Cambodia. Here's why the WHO is 'worried'". SBS News. Retrieved 2023-02-24.
  19. ^ "Viruses in Cambodian bird flu cases identified as endemic clade". Reuters. 26 February 2023. Archived from the original on 26 February 2023. Retrieved 27 February 2023.
  20. ^ Strong, Matthew (1 March 2023). "Taiwan raises Cambodia travel alert after human H5N1 cases | Taiwan News | 2023-03-01 16:02:00". Taiwan News. Archived from the original on 3 March 2023. Retrieved 3 March 2023.
  21. ^ Cheang, Sopheng (1 March 2023). "Cambodia says recent bird flu cases not spread by humans". ABC News. Archived from the original on 1 March 2023. Retrieved 3 March 2023.
  22. ^ "Argentina suspends poultry exports as first industrial case of bird flu confirmed". Reuters. 2023-03-01. Retrieved 2023-03-30.
  23. ^ Salgado, Daniela; López, Carlos (2023-03-25). "Influenza aviar: declaran emergencia zoosanitaria por contagio de cisnes de cuello negro en Valdivia". Radio Bío-Bío (in Spanish). Retrieved 2023-03-25.
  24. ^ a b c "En Uruguay siguen apareciendo casos de gripe aviar". Diario El Comercial (in Spanish). 2023-03-15. Retrieved 2023-03-22.
  25. ^ "Chile detects first case of bird flu in a human". Reuters. 2023-03-29. Retrieved 2023-03-30.
  26. ^ "Bird flu kills 400 seals, sea lions in Uruguay". phys.org. 30 September 2023. Archived from the original on 3 October 2023. Retrieved 3 October 2023.
  27. ^ "Domestic dog tests positive for avian influenza in Canada". Government of Canada. 2023-04-04. Retrieved 2023-04-04.
  28. ^ Mano, Ana (22 May 2023). "Brazil declares 180-day animal health emergency amid avian flu cases in wild birds". Reuters. Archived from the original on 22 May 2023. Retrieved 23 May 2023.
  29. ^ "First Human Influenza A(H5N1) (Bird Flu) Virus Infections in Cambodia". Centers for Disease Control and Prevention. 12 February 2024.
  30. ^ "Vietnam confirms H5N1 in man's avian flu death". CIDRAP. 2024-04-04. Retrieved 2024-04-04.{{cite web}}: CS1 maint: url-status (link)
  31. ^ "Philippines reports H5N1 bird flu outbreak on poultry farm". GMA News Online. 2024-04-05. Retrieved 2024-04-04.{{cite web}}: CS1 maint: url-status (link)
  32. ^ "Avian Influenza Current Situation Summary". Centers for Disease Control and Prevention. 7 March 2024.
  33. ^ "2022-2024 Detections of Highly Pathogenic Avian Influenza in Mammals". aphis.usda.gov.
  34. ^ Schnirring, Lisa (25 March 2024). "Sick cows in 2 states test positive for avian flu". University of Minnesota. CIDRAP. Retrieved 26 March 2024.
  35. ^ Schnirring, Lisa (1 April 2024). "Avian flu infects person exposed to sick cows in Texas". University of Minnesota. CIDRAP. Retrieved 2 April 2024.
  36. ^ Polansek, Tom (2024-04-05). "Bird flu dairy cow outbreak widens in Ohio, Kansas, New Mexico". GMA News Online. Retrieved 2024-04-04.
  37. ^ Orue, Maitane (2024-04-04). "The Idaho State Department of Agriculture detects HPAI in local dairy operation". KVMT. Retrieved 2024-04-04.
  38. ^ Thomas, Patrick. "Bird Flu Spreads to Cattle, Raising Fears on Farms". WSJ. Retrieved 2024-04-04.
  39. ^ Weston, Phoebe (27 February 2024). "Scientists confirm first cases of bird flu on mainland Antarctica". The Guardian. Retrieved 21 March 2024.
  40. ^ Tian, Jingman; Bai, Xiaoli; Li, Minghui; Zeng, Xianying; Xu, Jia; Li, Peng; Wang, Miao; Song, Xingdong; Zhao, Zhiguo; Tian, Guobin; Liu, Liling; Guan, Yuntao; Li, Yanbing; Chen, Hualan (July 2023). "Highly Pathogenic Avian Influenza Virus (H5N1) Clade 2.3.4.4b Introduced by Wild Birds, China, 2021". Emerging Infectious Diseases. 29 (7). doi:10.3201/eid2907.221149. PMC 10310395.
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