Influenza A virus subtype H1N1

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Influenza A virus subtype H1N1
Virus classification Edit this classification
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum:
Negarnaviricota
Class: Insthoviricetes
Order: Articulavirales
Family: Orthomyxoviridae
Genus: Alphainfluenzavirus
Species:
Serotype:
Influenza A virus subtype H1N1
Strains

In

orthomyxovirus that contains the glycoproteins hemagglutinin (H) and neuraminidase (N), antigens whose subtypes are used to classify the strains of the virus as H1N1, H1N2 etc. Hemagglutinin causes red blood cells to clump together and binds the virus to the infected cell. Neuraminidase is a type of glycoside hydrolase enzyme which helps to move the virus particles through the infected cell and assist in budding from the host cells.[1]

Some strains of H1N1 are

seasonal influenza, for instance in 2004–2005.[2] Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza). Its size is 80 to 120 nm (3.1×10−6 to 4.7×10−6 in) in diameter.[3]

Genetic analyses of virus from tissue preserved medically or in

1918 flu pandemic virus, but not conclusively so.[4][5]

Swine influenza

Swine influenza (also known as swine flu or pig flu) is a respiratory disease that occurs in pigs that is caused by the Influenza A virus. Influenza viruses that are normally found in swine are known as swine influenza viruses (SIVs). The known SIV strains include influenza C and the subtypes of influenza A known as H1N1,

H9N2 subtypes.[6]

Swine influenza virus is common throughout pig populations worldwide. Transmission of the virus from pigs to humans is not common and does not always lead to human influenza, often resulting only in the production of antibodies in the blood. If transmission does cause human influenza, it is called zoonotic swine flu or a variant virus. People with regular exposure to pigs are at increased risk of swine flu infection. Properly cooking the meat of an infected animal removes the risk of infection.

Pigs experimentally infected with the strain of swine flu that caused the

human pandemic of 2009–10 showed clinical signs of flu within four days, and the virus spread to other uninfected pigs housed with the infected ones.[7]

Incidents

1918–1920 flu pandemic

The 1918 flu was an unusually severe and deadly strain of H1N1[8] avian influenza, a viral infectious disease, that killed from 17[9] to 50 or more million people worldwide over about a year in 1918 and 1920. It was one of the deadliest pandemics in human history.

Soldiers march in front of the Pomona College Carnegie Library during the Spanish flu pandemic in 1918, all garbed in uniforms and face masks.

The 1918 flu caused an abnormally high number of deaths, possibly due to it provoking a

leukocyte migration towards the lungs, resulting in the destruction of lung cells and secretion of blood and mucus into the alveoli and airways. This makes it difficult for the patient to breathe and can result in suffocation. In contrast to other pandemics, which mostly kill the old and the very young, the 1918 pandemic killed unusual numbers of young adults, which may have been due to their healthy immune systems mounting a too-strong and damaging response to the infection.[13]

The term "Spanish" flu was coined because Spain was at the time the only European country where the press were printing reports of the outbreak, which had killed thousands in the armies fighting World War I (1914–1918). Other countries suppressed the news in order to protect morale.[14]

1976 swine flu outbreak

In 1976, a novel swine influenza A (H1N1) caused severe respiratory illness in 13 soldiers, with one death at

Fort Dix, New Jersey. The virus was detected only from 19 January to 9 February and did not spread beyond Fort Dix.[15] Retrospective serologic testing subsequently demonstrated that up to 230 soldiers had been infected with the novel virus, which was an H1N1 strain. The cause of the outbreak is still unknown and no exposure to pigs was identified.[16]

1977 Russian flu

The 1977 Russian flu pandemic was caused by strain Influenza A/USSR/90/77 (H1N1). It infected mostly children and young adults under 23; because a similar strain was prevalent in 1947–57, most adults had substantial immunity.[17][18] Later analysis found that the re-emergent strain had been circulating for approximately one year before it was detected in China and Russia.[19][20] The virus was included in the 1978–79 influenza vaccine.[21][22][23][24]

2009 A(H1N1) pandemic

Illustration of influenza antigenic shift

In the

human influenza and swine influenza
viruses, in all four different strains of subtype H1N1.

Preliminary genetic characterization found that the

matrix protein (M) genes resembled versions present in European swine flu isolates. The six genes from American swine flu are themselves mixtures of swine flu, bird flu, and human flu viruses.[26] While viruses with this genetic makeup had not previously been found to be circulating in humans or pigs, there is no formal national surveillance system to determine what viruses are circulating in pigs in the U.S.[27]

In April 2009, an outbreak of influenza-like illness (ILI) occurred in Mexico and then in the United States;[28] the CDC reported seven cases of novel A/H1N1 influenza and promptly shared the genetic sequences on the GISAID database.[29][30] With similar timely sharing of data for Mexican isolates,[31] by 24 April it became clear that the outbreak of ILI in Mexico and the confirmed cases of novel influenza A in the southwest US were related and WHO issued a health advisory on the outbreak of "influenza-like illness in the United States and Mexico".[28] The disease then spread very rapidly, with the number of confirmed cases rising to 2,099 by 7 May, despite aggressive measures taken by the Mexican government to curb the spread of the disease.[32] The outbreak had been predicted a year earlier by noticing the increasing number of replikins, a type of peptide, found in the virus.[33]

On 11 June 2009, the

national emergency.[35] The President's declaration caused many U.S. employers to take actions to help stem the spread of the swine flu and to accommodate employees and / or workflow which may have been impacted by an outbreak.[36]

A study conducted in coordination with the University of Michigan Health Service – scheduled for publication in the December 2009

arterial thrombus of infrarenal aorta, thrombosis of right external iliac vein and common femoral vein or cerebral gas embolism. The type of embolic events caused by H1N1 infection are summarized in a 2010 review by Dimitroulis Ioannis et al.[38]

The 21 March 2010 worldwide update, by the U.N.'s World Health Organization (WHO), states that "213 countries and overseas territories/communities have reported laboratory confirmed cases of pandemic influenza H1N1 2009, including at least 16,931 deaths."

T helper type 2 response to H1N1 influenza which may be responsible for the systemic inflammatory response syndrome that causes pulmonary edema and death.[42]

On 26 April 2011, an H1N1 pandemic preparedness alert was issued by the World Health Organization for the Americas.[43] In August 2011, according to the U.S. Geological Survey and the CDC, northern sea otters off the coast of Washington state were infected with the same version of the H1N1 flu virus that caused the 2009 pandemic and "may be a newly identified animal host of influenza viruses".[44] In May 2013, seventeen people died during an H1N1 outbreak in Venezuela, and a further 250 were infected.[45] As of early January 2014, Texas health officials have confirmed at least thirty-three H1N1 deaths and widespread outbreak during the 2013/2014 flu season,[46] while twenty-one more deaths have been reported across the US. Nine people have been reported dead from an outbreak in several Canadian cities,[47] and Mexico reports outbreaks resulting in at least one death.[48] Spanish health authorities have confirmed 35 H1N1 cases in the Aragon region, 18 of whom are in intensive care.[49] On 17 March 2014, three cases were confirmed with a possible fourth awaiting results occurring at the Centre for Addiction and Mental Health in Toronto, Ontario, Canada.[50]

2012 India outbreak

With more than 300 infections and over 20 deaths, India's health ministry declared an outbreak "well under control" with "no reason to panic" in April 2012.[51]

2015 India outbreak

According to the Indian Health Ministry, 31,974 cases of swine flu had been reported and 1,895 people had died from an outbreak by mid-March.[52][53]

2017 Maldives outbreak

Maldives reported swine flu in early 2017;

better source needed] 501 people were tested for the disease and 185 (37%) of those tested were positive for the disease. Four of those who tested positive from these 185 died due to this disease.[55]

The total number of people who have died due to the disease is unknown. Patient Zero was never identified.[56]

Schools were closed for a week due to the disease, but were ordered by the Ministry of Education to open after the holidays even though the disease was not fully under control.[57]

2017 Myanmar outbreak

Myanmar reported H1N1 in late July 2017. As of 27 July, there were 30 confirmed cases and six people had died.[58] The Ministry of Health and Sports of Myanmar sent an official request to WHO to provide help to control the virus; and also mentioned that the government would be seeking international assistance, including from the UN, China and the United States.[59]

2017–18 Pakistan outbreak

Pakistan reported H1N1 cases mostly arising from the city of Multan, with deaths resulting from the epidemic reaching 42.[60] There have also been confirmed cases in cities of Gujranwala and Lahore.

2019 Malta outbreak

An outbreak of swine flu in the European Union member state was reported in mid-January 2019, with the island's main state hospital overcrowded within a week, with more than 30 cases being treated.[61]

2019 Morocco outbreak

In January 2019 an outbreak of H1N1 was recorded in Morocco, with nine confirmed fatalities.[62]

2019 Iran outbreak

In November 2019 an outbreak of H1N1 was recorded in Iran, with 56 fatalities and 4,000 people hospitalized.[63]

G4 virus

The G4 virus, also known as the "G4 swine flu virus" (G4) and "G4 EA H1N1", is a swine influenza virus

Proceedings of the National Academy of Sciences (PNAS) stated that "G4 EA H1N1 viruses possess all the essential hallmarks of being highly adapted to infect humans ... Controlling the prevailing G4 EA H1N1 viruses in pigs and close monitoring of swine working populations should be promptly implemented."[65]

Michael Ryan, executive director of the World Health Organization (WHO) Health Emergencies Program, stated in July 2020 that this strain of influenza virus was not new and had been under surveillance since 2011.[66] The Chinese CDC said it had implemented an influenza surveillance program in 2010, analyzing more than 400,000 tests annually, to facilitate early identification of influenza.[67] Of those, 13 A(H1N1) cases were detected, of which three were of the G4 variant.[67]

The study stated that almost 30,000 swine had been monitored via nasal swabs between 2011 and 2018.[65] While other variants of the virus have appeared and diminished, the study claimed the G4 variant had sharply increased since 2016 to become the predominant strain.[65][68] The Chinese Ministry of Agriculture and Rural Affairs rebutted the study, saying that the number of pigs sampled was too small to demonstrate G4 had become the dominant strain and that the media had interpreted the study "in an exaggerated and nonfactual way".[69] They also said the infected workers "did not show flu symptoms and the test sample is not representative of the pig population in China".[67]

The US

Smithsonian Magazine reported in July 2020 that scientists agree that the virus should be closely monitored, but because it "so far cannot jump from person to person", it should not be a cause for alarm yet.[72]

In pregnancy

Pregnant women who contract the H1N1 infection are at greater risk of developing complications because of hormonal changes, physical changes and changes to their immune system to accommodate the growing fetus.[73] For this reason the Centers for Disease Control and Prevention recommends that those who are pregnant be vaccinated to prevent the influenza virus. The vaccination should not be taken by people who have had a severe allergic reaction to the influenza vaccination. Those who are moderately to severely ill, with or without a fever should wait until they recover before vaccination.[74]

Pregnant women who become infected with the influenza are advised to contact their doctor immediately. Influenza can be treated with prescription antiviral medications. Oseltamivir (trade name Tamiflu) and zanamivir (Relenza) are two neuraminidase inhibitors (antiviral medications) recommended. They are most effective when taken within two days of becoming sick.[75]

Since 1 October 2008, the CDC has tested 1,146 seasonal influenza A (H1N1) viruses for resistance against oseltamivir and zanamivir. It was found that 99.6% of the samples were resistant to oseltamivir while none were resistant to zanamivir. After 2009 Influenza A (H1N1) virus samples were tested, only 4% (of 853 samples) showed resistance to oseltamivir (again, no samples showed resistance to zanamivir).

embryotoxic (malformations and toxic effects on the embryo) when given at high doses in animal studies.[78]

References

  1. .
  2. ^ "Influenza Summary Update 20, 2004–2005 Season". FluView: A Weekly Influenza Surveillance Report. Centers for Disease Control and Prevention. Archived from the original on 16 October 2020. Retrieved 9 September 2017.
  3. from the original on 12 March 2020. Retrieved 25 August 2020.
  4. .
  5. ^ Clare Wilson (21 May 2022). "Deadly 1918 flu pandemic may be source of modern milder seasonal virus". New Scientist.
  6. from the original on 9 June 2021. Retrieved 9 June 2021.
  7. ^ "Humans May Give Swine Flu To Pigs In New Twist To Pandemic". Sciencedaily.com. 10 July 2009. Archived from the original on 26 January 2021. Retrieved 16 October 2010.
  8. ^ "1918 Pandemic (H1N1 virus) | Pandemic Influenza (Flu) | CDC". www.cdc.gov. 22 March 2020. Archived from the original on 27 March 2020. Retrieved 5 June 2020.
  9. PMID 30202996
    .
  10. .
  11. .
  12. .
  13. .
  14. from the original on 3 August 2020. Retrieved 1 September 2017.
  15. .
  16. ^ "Pandemic H1N1 2009 Influenza". CIDRAP. Center for Infectious Disease Research & Policy, University of Minnesota. Archived from the original on 27 October 2011. Retrieved 30 July 2011.
  17. ^ "Origin of current influenza H1N1 virus". virology blog. 2 March 2009. Archived from the original on 12 January 2012. Retrieved 22 December 2011.
  18. ^ "New Strain May Edge Out Seasonal Flu Bugs". NPR. 4 May 2009. Archived from the original on 26 January 2012. Retrieved 22 December 2011.
  19. S2CID 4207293
    .
  20. .
  21. ^ "Interactive health timeline box 1977: Russian flu scare". CNN. Archived from the original on 22 March 2007.
  22. ^ "Invasion from the Steppes". Time magazine. 20 February 1978. Archived from the original on 30 September 2007.
  23. ^ "Pandemic Influenza: Recent Pandemic Flu Scares". Global Security. Archived from the original on 24 June 2017. Retrieved 17 April 2007.
  24. ^ "Russian flu confirmed in Alaska". State of Alaska Epidemiology Bulletin (9). 21 April 1978. Archived from the original on 27 September 2006. Retrieved 17 April 2007.
  25. ^ "Deadly new flu virus in US and Mexico may go pandemic". New Scientist. 26 April 2009. Archived from the original on 29 April 2009. Retrieved 26 April 2009.
  26. ^ Susan Watts (25 April 2009). "Experts concerned about potential flu pandemic". BBC. Archived from the original on 2 April 2019. Retrieved 21 December 2019.
  27. from the original on 1 October 2009. Retrieved 9 September 2017.
  28. ^ a b "Influenza-like illness in the United States and Mexico". Disease Outbreak News. World Health Organization. 24 April 2009. Archived from the original on 26 April 2009. Retrieved 16 October 2010.
  29. ^ "Viral gene sequences to assist update diagnostics for swine influenza A(H1N1)" (PDF). World Health Organization. 15 April 2009. Archived (PDF) from the original on 7 August 2017. Retrieved 31 August 2017.
  30. .
  31. ^ "Influenza cases by a new sub-type: Regional Update". Pan American Health Organization (PAHO). Epidemiological Alerts Vol. 6, No. 15. 29 April 2009. Archived from the original on 1 September 2017. Retrieved 31 August 2017.
  32. ^ "Influenza A(H1N1) – update 19". Disease Outbreak News. World Health Organization. 7 May 2009. Archived from the original on 7 May 2009. Retrieved 16 October 2010.
  33. ^ "Efforts To Quickly Develop Swine Flu Vaccine". Science Daily. 4 June 2009. Archived from the original on 31 July 2009. Retrieved 28 December 2016. One company, Replikins, actually predicted over a year ago that significant outbreaks of the H1N1 flu virus would occur within 6–12 months.
  34. ^ "H1N1 Pandemic – It's Official". 11 June 2009. Archived from the original on 15 June 2009.
  35. ^ "Obama declares swine flu a national emergency". The Daily Herald. 2009. Archived from the original on 29 October 2009. Retrieved 26 October 2009.
  36. National Law Review. Davis Wright Tremaine, LLP. 2 November 2009. Archived
    from the original on 15 October 2011. Retrieved 3 November 2011.
  37. .
  38. ^ Dimitroulis I, Katsaras M, Toumbis (October 2010). "H1N1 infection and embolic events. A multifaceted disease". Pneumon. 29 (3): 7–13. Archived from the original on 13 December 2019. Retrieved 1 November 2016.
  39. ^ "Situation updates – Pandemic (H1N1) 2009". World Health Organization. Archived from the original on 2 May 2009. Retrieved 16 October 2010.
  40. ^ "Pandemic (H1N1) 2009 – update 103". Disease Outbreak News. World Health Organization. 4 June 2010. Archived from the original on 9 June 2010. Retrieved 16 October 2010.
  41. ^ "H1N1 Pandemic Flu Hits Pregnant Women Hard". Businessweek.com. 24 May 2010. Archived from the original on 5 June 2010. Retrieved 16 October 2010.
  42. PMID 19858268
    .
  43. ^ "WHO Issues H1N1 Pandemic Alert". Recombinomics.com. 26 April 2011. Archived from the original on 29 April 2011. Retrieved 28 April 2011.
  44. ^ Rogall, Gail Moede (8 April 2014). "Sea Otters Can Get the Flu, Too". U.S. Department of the Interior, U.S. Geological Survey. Archived from the original on 13 April 2014. Retrieved 11 April 2014.
  45. ^ "H1N1 flu outbreak kills 17 in Venezuela: media". Reuters. 27 May 2013. Archived from the original on 30 March 2019. Retrieved 5 July 2021.
  46. ^ "North Texas confirmed 20 flu deaths – Xinhua". English.news.cn. Archived from the original on 12 January 2014.
  47. ^ "9 deaths caused by H1N1 flu in Alberta". Cbc.ca. Archived from the original on 19 May 2020. Retrieved 10 February 2019.
  48. ^ "Un muerto en Coahuila por influenza AH1N1". Vanguardia.com.mx. 3 January 2014. Archived from the original on 7 January 2014. Retrieved 8 January 2014.
  49. ^ "Aumentan a 35 los hospitalizados por gripe A en Aragón". Cadenaser.com. 12 January 2014. Archived from the original on 12 January 2014. Retrieved 12 January 2014.
  50. ^ "Three cases of H1N1 reported at CAMH". Thestar.com. 21 March 2014. Archived from the original on 30 March 2019. Retrieved 10 February 2019.
  51. ^ "India swine flu 'under control'". BBC News. 12 April 2012. Archived from the original on 20 July 2020. Retrieved 20 July 2020.
  52. ^ "Swine flu toll inches towards 1,900". The Hindu. 19 March 2015. Archived from the original on 20 March 2015. Retrieved 20 July 2020.
  53. PMID 27748308
    .
  54. ^ "Makeshift flu clinics swamped as H1N1 cases rise to 82". Maldives Independent.com. 15 March 2017. Archived from the original on 24 March 2017. Retrieved 25 March 2017.
  55. ^ "Breaking: Swine flu gai Ithuru meehaku maruve, ithuru bayaku positive vejje". Mihaaru.com. 25 March 2017. Archived from the original on 25 March 2017. Retrieved 25 March 2017.
  56. ^ "H1N1 death toll rises to three". Maldives Independent.com. 21 March 2017. Archived from the original on 26 March 2017. Retrieved 25 March 2017.
  57. ^ "Schools to open after flu outbreak". Maldives Independent.com. 23 March 2017. Archived from the original on 26 March 2017. Retrieved 25 March 2017.
  58. ^ Lone, Wa; Lewis, Simon (27 July 2017). "Myanmar tracks spread of H1N1 as outbreak claims sixth victim". Reuters. Archived from the original on 11 December 2018. Retrieved 16 August 2019.
  59. ^ Htet Naing Zaw (27 July 2017). "Myanmar Asks WHO to Help Fight H1N1 Virus". The Irrawaddy. Archived from the original on 28 August 2019. Retrieved 16 August 2019.
  60. ^ "Toll rises to 42 as 3 more succumb to swine flu". The Nation. 24 January 2018. Archived from the original on 25 January 2018. Retrieved 25 January 2018.
  61. ^ Caruana, Claire; Xuereb, Matthew (18 January 2019). "Swine flu outbreak at Mater Dei hospital, St Vincent de Paul". Times of Malta. Archived from the original on 16 August 2019. Retrieved 16 August 2019.
  62. ^ "Swine flu outbreak kills 9 in Morocco". Al Arabiya. AFP. 2 February 2019. Archived from the original on 16 August 2019. Retrieved 16 August 2019.
  63. ^ "آنفولانزا و راه‌های درمان آن را بشناسید" [Learn about the flu and how to treat it]. yjc.ir (in Persian). Archived from the original on 3 December 2019. Retrieved 3 December 2019.
  64. ^ a b c d "CDC takes action to prepare against 'G4' swine flu viruses in China with pandemic potential" (Press release). Centers for Disease Control and Prevention. 2 July 2020. Archived from the original on 3 July 2020. Retrieved 3 July 2020.
  65. ^
    PMID 32601207
    .
  66. ^ "Recently publicized swine flu not new, under surveillance since 2011: WHO expert". Xinhuanet. 2 July 2020. Archived from the original on 3 July 2020. Retrieved 2 July 2020.
  67. ^ a b c "The swine flu virus is not a new virus and does not very spread and is pathogenic to humans and animals [translated from Chinese]". Ministry of Agriculture of the People's Republic of China. 2020. Archived from the original on 20 July 2020. Retrieved 20 July 2020. Translation via "Eurasian avian-like A(H1N1) swine influenza viruses" (PDF). European Centre for Disease Prevention and Control. 13 July 2020. Archived (PDF) from the original on 19 July 2020. Retrieved 20 July 2020.
  68. S2CID 225687803
    .
  69. ^ "China says G4 swine flu virus not new; does not infect humans easily". Reuters. 4 July 2020. Archived from the original on 4 July 2020. Retrieved 4 July 2020.
  70. ^ a b c "Eurasian avian-like A(H1N1) swine influenza viruses" (PDF). European Centre for Disease Prevention and Control. 13 July 2020. Archived (PDF) from the original on 19 July 2020. Retrieved 20 July 2020.
  71. ^ a b Garcia de Jesus E (2 July 2020). "4 reasons not to worry about that 'new' swine flu in the news". Science News. Archived from the original on 2 July 2020. Retrieved 3 July 2020.
  72. ^ Machemer T (6 July 2020). "New Swine flu strain with pandemic potential isn't cause for alarm". Smithsonian Magazine. Archived from the original on 11 July 2020. Retrieved 20 July 2020.
  73. PMID 22851818
    .
  74. ^ "Key Facts about Seasonal Flu Vaccine". Centers for Disease Control and Prevention. 2013. Archived from the original on 30 June 2017. Retrieved 31 January 2014.
  75. ^ "What You Should Know About Flu Antiviral Drugs". Centers for Disease Control and Prevention. Archived from the original on 23 January 2014. Retrieved 31 January 2014.
  76. ^ "2008–2009 Influenza Season Week 32 ending 15 August 2009". Centers for Disease Control and Prevention. Archived from the original on 9 July 2017. Retrieved 31 January 2014.
  77. PMID 23583838
    .
  78. ^ "Pandemic OBGYN". Sarasota Memorial Health Care System. Archived from the original on 3 February 2014. Retrieved 31 January 2014.

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