Jump to content

Pandemic H1N1/09 virus: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
← Previous editNext edit →
Content deleted Content added
VisualWikitext
Sagan666 (talk | contribs)
94 edits
m added missing period
moved from 2009 flu pandemic article to trim size; not cleaned up
Line 3: Line 3:


The '''Pandemic H1N1/09 virus''' is a [[swine influenza|swine-origin]] [[influenza]] A([[H1N1]]) virus strain responsible for the [[2009 flu pandemic]].
The '''Pandemic H1N1/09 virus''' is a [[swine influenza|swine-origin]] [[influenza]] A([[H1N1]]) virus strain responsible for the [[2009 flu pandemic]].

==Virus characteristics==
The virus is a novel strain of influenza. Existing [[vaccination|vaccines]] against seasonal flu provide no protection, and there is no vaccine for this strain. A study at the U.S. Centers for Disease Control and Prevention published in May 2009 found that children had no preexisting immunity to the new strain but that adults, particularly those over 60, had some degree of immunity. Children showed no cross-reactive antibody reaction to the new strain, adults aged 18 to 64 had 6-9%, and older adults 33%.<ref>[http://www.cidrap.umn.edu/cidrap/content/influenza/swineflu/news/may2109serum-jw.html CIDRAP news: Some immunity to novel H1N1 flu found in seniors, 21 May 2009]</ref><ref name="CDC_MMWRDispatch_20090421">{{cite news |publisher=U.S. Centers for Disease Control |url=http://www.cdc.gov/mmwr/preview/mmwrhtml/mm58d0421a1.htm |title=Morbidity and Mortality Weekly Report Dispatch |date=21 April 2009}}</ref> It was also determined that the strain contained genes from five different flu viruses: North American swine influenza, North American avian influenza, human influenza, and two swine influenza viruses typically found in Asia and Europe. Further analysis showed that several of the proteins of the virus are most similar to strains that cause mild symptoms in humans, leading virologist Wendy Barclay to suggest on May 1 that the initial indications are that the virus was unlikely to cause severe symptoms for most people.<ref>{{cite news |url=http://news.bbc.co.uk/2/hi/health/8028371.stm |title=What scientists know about swine flu |publisher=BBC News |author=Emma Wilkinson |date=2009-05-01}}</ref> Scientists in Winnipeg completed the first full genetic sequencing of the virus on 6 May.<ref>{{cite press release |title=H1N1 virus genome: 'This is a world first' |date=May 6, 2009 |publisher=Independent |place=Cape Town |agency=Agence France Press |url=http://www.iol.co.za/index.php?art_id=nw20090506191835578C369647&click_id=31&set_id=1 |accessdate=May 6, 2009}}</ref>

===Virus origins===
On June 23, the ''New York Times'' reported that U.S. federal agriculture officials, "contrary to the popular assumption that the new swine flu pandemic arose on factory farms in Mexico," now believe that it "most likely emerged in pigs in Asia, but then traveled to North America in a human." They emphasized that there was no way to prove their theory, but stated that there is no evidence that this new virus, which combines Eurasian and North American genes, has ever circulated in North American pigs, "while there is tantalizing evidence that a closely related 'sister virus' has circulated in Asia."<ref name=NYT6-23/>

In early June 2009, using computational methods developed over the last ten years at Oxford, Dr Oliver Pybus of Oxford University's Department of Zoology and his team attempted to reconstruct the origins and timescale of the 2009 flu pandemic. He claims "Our results show that this strain has been circulating among pigs, possibly among multiple continents, for many years prior to its transmission to humans." The research team that worked on this report also believe that it was "derived from several viruses circulating in swine," and that the initial transmission to humans occurred several months before recognition of the outbreak. The team concluded that "despite widespread influenza surveillance in humans, the lack of systematic swine surveillance allowed for the undetected persistence and evolution of this potentially pandemic strain for many years."<ref name=OxfordU>{{cite journal|title=Origins and evolutionary genomics of the 2009 swine-origin H1N1 influenza A epidemic |author=Smith GJD, Vijaykrishna D, Bahl J, Lycett SJ, Worobey M, Pybus OG, Ma SK, Cheung CL, Raghwani J, Bhatt S, Peiris JSM, Guan Y & Rambaut A |journal=Nature |doi=10.1038/nature08182 |date=11 June 2009|laysummary=http://www.ox.ac.uk/media/news_stories/2009/090611_1.html|volume=459|pages=1122}} (near-final letter)</ref>

[[File:3D Influenza virus.png|thumb|Structure of the influenza [[wikt:virion|virion]]. The [[hemagglutinin]] (HA) and [[neuraminidase]] (NA) proteins are shown on the surface of the particle. The viral RNAs that make up the [[genome]] are shown as red coils inside the particle and bound to ribonucleoproteins (RNPs).]]

According to the researchers, movement of live pigs between [[Eurasia]] and [[North America]] "seems to have facilitated the mixing of diverse swine influenza viruses, leading to the multiple reassortment events associated with the genesis of the (new H1N1) strain." They also stated that this new pandemic "provides further evidence of the role of domestic pigs in the ecosystem of influenza A."<ref name=Reuters6-11/> Some experts also suspect that a leading cause of the new virus outbreak is insufficient surveillance by the pork industry and the fact that "animal husbandry now more closely resembles the petrochemical industry than the happy family farm"<ref>Davis, Mike. [http://www.alternet.org/healthwellness/138798/the_swine_flu_crisis_lays_bare_the_meat_industry%27s_monstrous_power/?page=1 "The Swine Flu Crisis Lays Bare the Meat Industry's Monstrous Power"] ''Alternet.org'', April 28, 2009</ref>

===Estimates of total cases===
According to the WHO, the pandemic was still in its early stages globally and two billion infections over the course of the pandemic could be expected<ref>[http://www.cbsnews.com/stories/2009/07/24/world/main5185752.shtml?tag=cbsnewsLeadStoriesAreaMain;cbsnewsLeadStoriesHeadlines "WHO: Swine Flu Could Infect 2 Billion"] ''CBS News'', July 24, 2009</ref> The U.S. CDC's National Center for Immunization and Respiratory Disease estimated that 12% to 24% of Americans might get swine flu this fall and winter if there is no working vaccine. Initial availability of vaccines is expected by mid-October, although healthcare workers and people most at risk would likely get them first.<ref>[http://www.webmd.com/cold-and-flu/news/20090724/new-estimate-on-swine-flu-in-us "CDC Says Up to 24% of Americans Might Get Swine Flu if There Is No Vaccine"] ''WebMD'', July 24, 2009</ref>

In late June, the CDC estimated that 1 million Americans had so far contracted the flu.

By comparison, an estimated 15 million to 60 million Americans are infected with the seasonal flu each year, leading to roughly 36,000 deaths.<ref>[http://www.forbes.com/feeds/hscout/2009/06/25/hscout628467.html "1 Million Americans Likely Stricken by Swine Flu: CDC"] ''Forbes'', June 25, 2009</ref> According to the CDC, however, only about one in 20 cases was being officially reported in the U.S.<ref name=Bloomberg5-25>{{cite news |url=http://www.bloomberg.com/apps/news?pid=20601081&sid=aELZw0YSTTiI&refer=australia |title=Swine flu is spreading more widely than official numbers show |agency=Bloomberg News |date=25May 2009}}</ref> In the U.K., some experts thought the number of cases was potentially 300 times more than early published estimates,<ref name=Indep5-24>{{cite news |url=http://www.independent.co.uk/life-style/health-and-wellbeing/health-news/uk-swine-flu-toll-is-really-30000-says-leading-scientist-1690130.html |title=UK swine flu toll is really 30,000, says leading scientist |publisher=The Independent |date=24 May 2009}}</ref> warning that case estimates by the U.K. and other governments were highly inaccurate.

The CDC has discontinued reporting confirmed cases and will now only report Flu Hospitalizations and Deaths on a weekly basis.

As of August 21, There have been 7,983 Hospitalizations and 522 Deaths in the US reported to the CDC for 2009.

===Virulence===
The CDC has noted that most infections continue to be mild, similar to seasonal flu, and that recovery tends to be fairly quick.<ref name=Atlanta>{{cite news |url=http://www.ajc.com/health/content/shared-auto/healthnews/cdc-/627172.html |title=Swine flu may have infected more than 100,000 Americans |publisher=Atlanta Journal-Constitution |date=17 May 2009}}</ref> Deaths so far have been only a tiny fraction of the amount of people who die every year from seasonal flu<ref>[http://www.nydailynews.com/ny_local/2009/06/07/2009-06-07_250_times_as_many_die_from_regular_flu_swines_new__scary__but_not_nearly_as_dead.html#ixzz0HmggXARQ&D "Swine flue may be scary, but 250 times as many die from regular flu"] ''New York Daily News'', June 7, 2009</ref><ref>[http://townhall.com/columnists/MichaelFumento/2009/07/30/figuring_how_to_terrify_us_over_swine_flu?page=full "Figuring How to Terrify Us Over Swine Flu"] ''Townhall'', July 30, 2009</ref>

===Mutation potential===
On May 22, 2009, WHO chief Dr. [[Margaret Chan]] said that the virus must be closely monitored in the southern hemisphere, as it could mix with ordinary seasonal influenza and change in unpredictable ways. "In cases where the H1N1 virus is widespread and circulating within the general community, countries must expect to see more cases of severe and fatal infections," she said. "<ref name=Intellasia>{{cite news |url=http://www.intellasia.net/news/articles/health/111265498.shtml |title=WHO chief warns H1N1 swine flu likely to worsen |publisher=Intellasia |date=May 23, 2009}}</ref> Experts writing in the July ''New England Journal of Medicine'' note that "historically, pandemic viruses have evolved between seasons, and the current strain may become more severe or transmissible in the coming months." They therefore stress that "international cooperation will be crucial" to engage in proper surveillance to help monitor changes in the virus's behavior, which will aid in both "vaccine targeting" and interpreting illness patterns in the fall of 2009.<ref name=NEJM>[http://content.nejm.org/cgi/content/full/NEJMp0904380 "Managing and Reducing Uncertainty in an Emerging Influenza Pandemic"] ''New England Journal of Medicine'', July 9, 2009</ref>

Other experts are also concerned that the new virus strain could [[mutate]] over the coming months. Guan Yi, a leading virologist from the [[University of Hong Kong]], for instance, described the new H1N1 influenza virus as "very unstable", meaning it could mix and swap genetic material when exposed to other viruses. During an interview he said "Both H1N1 and [[H5N1 avian influenza|H5N1]] are unstable so the chances of them exchanging genetic material are higher, whereas a stable (seasonal flu) virus is less likely to take on genetic material." The H5N1 virus is mostly limited to birds, but in rare cases when it infects humans it has a mortality rate of between 60% to 70%.<ref name=Yi>{{cite news |url=http://www.reuters.com/article/asiaCrisis/idUSHKG147261 |title=New virus "very unstable", more changes seen-expert |agency=Reuters |date=May 12, 2009}}</ref> Experts worry about the emergence of a hybrid of the more [[Virulence|virulent]] Asian-lineage HPAI (highly pathogenic avian influenza) A/H5N1 strain (media labeled "bird flu") with more human-transmissible Influenza A strains such as this novel 2009 swine-origin A/H1N1 strain (media labeled "swine flu"), especially since the H5N1 strain is and has been for years [[endemic (epidemiology)|endemic]] in birds in countries like [[China]], [[Indonesia]], [[Vietnam]] and [[Egypt]].<ref name=Yi/><ref>{{cite web |url=http://www.fao.org/docs/eims/upload//246457/aj097e00.pdf |format=PDF |date=July 25, 2008 |publisher=[[FAO]] |title=Avian Influenza Disease Emergency Situation Update}}</ref> (See the suite of [[H5N1]] articles for details.)

Nor had federal health officials in the U.S. dismissed the possibility that the worst was yet to come. "Far from it," Ann Schuchat of the CDC says, noting that the horrific 1918 flu epidemic, which killed hundreds of thousands in the United States alone, was preceded by a mild "herald" wave of cases in the spring, followed by devastating waves of illness in the autumn. "That 1918 experience is in our minds," she said.<ref name="USAToday5-26">{{cite news|url=http://www.usatoday.com/news/health/2009-05-26-swine-flu-decrease_N.htm |title=CDC expert says flu outbreak is dying down – for now |author=Steve Sternberg |date=May 26, 2009}}</ref>

As of late July, U.S. health officials said that the swine flu "isn't yet mutating to become more dangerous," but they are closely tracking that as the virus continues to circle the globe.<ref name=AP-7-23>[http://www.google.com/hostednews/ap/article/ALeqM5gcx9bjqSn_mHLMw5rb3eoY32TZdQD99K6PF00 "CDC says no sign yet that swine flu is mutating"] ''Associated Press'', July 23, 2009</ref>

===Infection among animals===
;Swine
Before being transmitted to humans, the viruses have circulated in swine which has allowed for the undetected persistence and evolution of this potentially pandemic strain for many years.

;Birds
In late August, the government of [[Chile]] discovered that the swine flu virus had jumped to birds, "opening a new chapter in the global epidemic." Top flu and animal-health experts with WHO and the CDC were monitoring the situation closely, but said the infected turkeys have suffered only mild effects, easing concern about a potentially dangerous development. Chile's turkey meat remains safe to eat, they said, and so far there have been no signs of a potentially dangerous mutation.<ref>[http://news.yahoo.com/s/ap/20090821/ap_on_re_la_am_ca/lt_swine_flu_turkeys "Chile confirms swine flu in turkeys"] ''Associated Press'', Aug. 21, 2009</ref>


==Nomenclature==
==Nomenclature==

Revision as of 02:04, 30 August 2009

This article is about the virus which is causing the 2009 flu pandemic. For information about the outbreak itself, see 2009 flu pandemic.
For information on ways to decrease one's chances of contracting H1N1, see influenza prevention.

The Pandemic H1N1/09 virus is a swine-origin influenza A(H1N1) virus strain responsible for the 2009 flu pandemic.

Virus characteristics

The virus is a novel strain of influenza. Existing vaccines against seasonal flu provide no protection, and there is no vaccine for this strain. A study at the U.S. Centers for Disease Control and Prevention published in May 2009 found that children had no preexisting immunity to the new strain but that adults, particularly those over 60, had some degree of immunity. Children showed no cross-reactive antibody reaction to the new strain, adults aged 18 to 64 had 6-9%, and older adults 33%.[1][2] It was also determined that the strain contained genes from five different flu viruses: North American swine influenza, North American avian influenza, human influenza, and two swine influenza viruses typically found in Asia and Europe. Further analysis showed that several of the proteins of the virus are most similar to strains that cause mild symptoms in humans, leading virologist Wendy Barclay to suggest on May 1 that the initial indications are that the virus was unlikely to cause severe symptoms for most people.[3] Scientists in Winnipeg completed the first full genetic sequencing of the virus on 6 May.[4]

Virus origins

On June 23, the New York Times reported that U.S. federal agriculture officials, "contrary to the popular assumption that the new swine flu pandemic arose on factory farms in Mexico," now believe that it "most likely emerged in pigs in Asia, but then traveled to North America in a human." They emphasized that there was no way to prove their theory, but stated that there is no evidence that this new virus, which combines Eurasian and North American genes, has ever circulated in North American pigs, "while there is tantalizing evidence that a closely related 'sister virus' has circulated in Asia."[5]

In early June 2009, using computational methods developed over the last ten years at Oxford, Dr Oliver Pybus of Oxford University's Department of Zoology and his team attempted to reconstruct the origins and timescale of the 2009 flu pandemic. He claims "Our results show that this strain has been circulating among pigs, possibly among multiple continents, for many years prior to its transmission to humans." The research team that worked on this report also believe that it was "derived from several viruses circulating in swine," and that the initial transmission to humans occurred several months before recognition of the outbreak. The team concluded that "despite widespread influenza surveillance in humans, the lack of systematic swine surveillance allowed for the undetected persistence and evolution of this potentially pandemic strain for many years."[6]

Structure of the influenza virion. The hemagglutinin (HA) and neuraminidase (NA) proteins are shown on the surface of the particle. The viral RNAs that make up the genome are shown as red coils inside the particle and bound to ribonucleoproteins (RNPs).

According to the researchers, movement of live pigs between Eurasia and North America "seems to have facilitated the mixing of diverse swine influenza viruses, leading to the multiple reassortment events associated with the genesis of the (new H1N1) strain." They also stated that this new pandemic "provides further evidence of the role of domestic pigs in the ecosystem of influenza A."[7] Some experts also suspect that a leading cause of the new virus outbreak is insufficient surveillance by the pork industry and the fact that "animal husbandry now more closely resembles the petrochemical industry than the happy family farm"[8]

Estimates of total cases

According to the WHO, the pandemic was still in its early stages globally and two billion infections over the course of the pandemic could be expected[9] The U.S. CDC's National Center for Immunization and Respiratory Disease estimated that 12% to 24% of Americans might get swine flu this fall and winter if there is no working vaccine. Initial availability of vaccines is expected by mid-October, although healthcare workers and people most at risk would likely get them first.[10]

In late June, the CDC estimated that 1 million Americans had so far contracted the flu.

By comparison, an estimated 15 million to 60 million Americans are infected with the seasonal flu each year, leading to roughly 36,000 deaths.[11] According to the CDC, however, only about one in 20 cases was being officially reported in the U.S.[12] In the U.K., some experts thought the number of cases was potentially 300 times more than early published estimates,[13] warning that case estimates by the U.K. and other governments were highly inaccurate.

The CDC has discontinued reporting confirmed cases and will now only report Flu Hospitalizations and Deaths on a weekly basis.

As of August 21, There have been 7,983 Hospitalizations and 522 Deaths in the US reported to the CDC for 2009.

Virulence

The CDC has noted that most infections continue to be mild, similar to seasonal flu, and that recovery tends to be fairly quick.[14] Deaths so far have been only a tiny fraction of the amount of people who die every year from seasonal flu[15][16]

Mutation potential

On May 22, 2009, WHO chief Dr. Margaret Chan said that the virus must be closely monitored in the southern hemisphere, as it could mix with ordinary seasonal influenza and change in unpredictable ways. "In cases where the H1N1 virus is widespread and circulating within the general community, countries must expect to see more cases of severe and fatal infections," she said. "[17] Experts writing in the July New England Journal of Medicine note that "historically, pandemic viruses have evolved between seasons, and the current strain may become more severe or transmissible in the coming months." They therefore stress that "international cooperation will be crucial" to engage in proper surveillance to help monitor changes in the virus's behavior, which will aid in both "vaccine targeting" and interpreting illness patterns in the fall of 2009.[18]

Other experts are also concerned that the new virus strain could mutate over the coming months. Guan Yi, a leading virologist from the University of Hong Kong, for instance, described the new H1N1 influenza virus as "very unstable", meaning it could mix and swap genetic material when exposed to other viruses. During an interview he said "Both H1N1 and H5N1 are unstable so the chances of them exchanging genetic material are higher, whereas a stable (seasonal flu) virus is less likely to take on genetic material." The H5N1 virus is mostly limited to birds, but in rare cases when it infects humans it has a mortality rate of between 60% to 70%.[19] Experts worry about the emergence of a hybrid of the more virulent Asian-lineage HPAI (highly pathogenic avian influenza) A/H5N1 strain (media labeled "bird flu") with more human-transmissible Influenza A strains such as this novel 2009 swine-origin A/H1N1 strain (media labeled "swine flu"), especially since the H5N1 strain is and has been for years endemic in birds in countries like China, Indonesia, Vietnam and Egypt.[19][20] (See the suite of H5N1 articles for details.)

Nor had federal health officials in the U.S. dismissed the possibility that the worst was yet to come. "Far from it," Ann Schuchat of the CDC says, noting that the horrific 1918 flu epidemic, which killed hundreds of thousands in the United States alone, was preceded by a mild "herald" wave of cases in the spring, followed by devastating waves of illness in the autumn. "That 1918 experience is in our minds," she said.[21]

As of late July, U.S. health officials said that the swine flu "isn't yet mutating to become more dangerous," but they are closely tracking that as the virus continues to circle the globe.[22]

Infection among animals

Swine

Before being transmitted to humans, the viruses have circulated in swine which has allowed for the undetected persistence and evolution of this potentially pandemic strain for many years.

Birds

In late August, the government of Chile discovered that the swine flu virus had jumped to birds, "opening a new chapter in the global epidemic." Top flu and animal-health experts with WHO and the CDC were monitoring the situation closely, but said the infected turkeys have suffered only mild effects, easing concern about a potentially dangerous development. Chile's turkey meat remains safe to eat, they said, and so far there have been no signs of a potentially dangerous mutation.[23]

Nomenclature

On 30 April 2009, World Health Organization (WHO) spokesman Dick Thompson said that because of the banning of pork products and the slaughter of pigs, "Rather than calling this swine flu ... we're going to stick with the technical scientific name H1N1 influenza A"[24]

In July 2009 the WHO stated[25]

"As you know, since the emergence of the pandemic, the name of the virus has been a difficult issue for many reasons. In the past, we have seen how the naming of viruses by location can stigmatize those locations and we have also seen in this and in other episodes where associating the virus with one animal species or another, can really cause both anxiety and then fears about food and in this particular instance, about pork. So, in recognition of those issues, what WHO, FAO and OIE did, actually some weeks ago, was to get together several of the experts who work in these organizations and with many of the laboratory experts who work with these organizations, and then we had a meeting – a virtual meeting – in which these issues were discussed and one of the things that we wanted to do was make sure that any naming of the virus was scientifically accurate but also would avoid any kind of adverse reactions to the name or to minimize those as much as possible. Based on those discussions, what the experts decided – calling this a pandemic H1N1/09 virus – was a good way to distinguish it from the current seasonal H1N1 viruses and to do so, in a way which was scientifically sound, but also would avoid some of the stigma associated with other options."

On 5 August 2009 the United States Centers for Disease Control and Prevention were calling it the novel H1N1 virus.[26]

Genetics

Template:2009 swine flu genetic table

On April 24, the U.S. Centers for Disease Control and Prevention (CDC) determined that seven samples from suspected cases in Mexico matched the strain that had infected patients in Texas and California with no known linkages to animals or one another; the strain appeared to be spreading from human to human.[27][28] The CDC determined that the strain contained genes from four different flu viruses – North American swine influenza, North American avian influenza, human influenza, and swine influenza virus typically found in Asia and Europe – "an unusually mongrelised mix of genetic sequences."[29][30] A CDC investigative team arrived in Mexico City on April 25 to work with Mexican counterparts to study the virus.[31]

Pigs are susceptible to influenza viruses that can also infect both humans and birds, so they may act as a "mixing vessel" in which reassortment can occur between flu viruses of several species.[32][33] Reassortment is a process that happens if two different types of influenza virus infect a single cell and it can produce a new strain of influenza. This is because the virus genome is split between eight independent pieces of RNA, which allows pieces of RNA from different viruses to mix together and form a novel type of virus as new virus particles are being assembled.[34] This new strain appears to be a result of the reassortment of two swine influenza viruses, one from North America and one from Europe.[35] But the North American pig strain was itself the product of previous reassortments, and has carried an avian PB2 gene for at least ten years and a human PB1 gene since 1993.[36] These genes were passed on to the new virus.[37][38]

Gene sequences for every viral gene were made available through the Global Initiative on Sharing Avian Influenza Data (GISAID).[39][40] A preliminary analysis found that the hemagglutinin (HA) gene was similar to that of swine flu viruses present in U.S. pigs since 1999, but the neuraminidase (NA) and matrix protein (M) genes resembled versions present in European swine flu isolates. 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.[41] So far, little is known about the spread of the virus in any pig population. A preliminary analysis has also shown that several of the proteins involved in the pathophysiology of the virus are most similar to strains that cause mild symptoms in humans. This suggests that the virus is unlikely to cause severe infections similar to those caused by the 1918 pandemic flu virus or the H5N1 avian influenza.[42]

Late on May 6, Canada's National Microbiology Laboratory first completed the sequencing of the virus, publishing the result to GenBank. Samples from Mexico, Nova Scotia and Ontario had the same sequence, ruling out genetic explanations for the greater severity of the Mexican cases.[43][44]

The genetic divergence of the virus in samples from different cases has been analysed by Mike Worobey at the University of Arizona at Tucson, USA, who found that the virus jumped to humans in 2008 probably after June, and not later than the end of November.[45]


See also

References

  1. ^ CIDRAP news: Some immunity to novel H1N1 flu found in seniors, 21 May 2009
  2. ^ "Morbidity and Mortality Weekly Report Dispatch". U.S. Centers for Disease Control. 21 April 2009.
  3. ^ Emma Wilkinson (2009-05-01). "What scientists know about swine flu". BBC News.
  4. ^ "H1N1 virus genome: 'This is a world first'" (Press release). Cape Town: Independent. Agence France Press. May 6, 2009. Retrieved May 6, 2009.
  5. ^ Cite error: The named reference NYT6-23 was invoked but never defined (see the help page).
  6. ^ Smith GJD, Vijaykrishna D, Bahl J, Lycett SJ, Worobey M, Pybus OG, Ma SK, Cheung CL, Raghwani J, Bhatt S, Peiris JSM, Guan Y & Rambaut A (11 June 2009). "Origins and evolutionary genomics of the 2009 swine-origin H1N1 influenza A epidemic". Nature. 459: 1122. doi:10.1038/nature08182. {{cite journal}}: Unknown parameter |laysummary= ignored (help)CS1 maint: multiple names: authors list (link) (near-final letter)
  7. ^ Cite error: The named reference Reuters6-11 was invoked but never defined (see the help page).
  8. ^ Davis, Mike. "The Swine Flu Crisis Lays Bare the Meat Industry's Monstrous Power" Alternet.org, April 28, 2009
  9. ^ "WHO: Swine Flu Could Infect 2 Billion" CBS News, July 24, 2009
  10. ^ "CDC Says Up to 24% of Americans Might Get Swine Flu if There Is No Vaccine" WebMD, July 24, 2009
  11. ^ "1 Million Americans Likely Stricken by Swine Flu: CDC" Forbes, June 25, 2009
  12. ^ "Swine flu is spreading more widely than official numbers show". Bloomberg News. 25May 2009. {{cite news}}: Check date values in: |date= (help)
  13. ^ "UK swine flu toll is really 30,000, says leading scientist". The Independent. 24 May 2009.
  14. ^ "Swine flu may have infected more than 100,000 Americans". Atlanta Journal-Constitution. 17 May 2009.
  15. ^ "Swine flue may be scary, but 250 times as many die from regular flu" New York Daily News, June 7, 2009
  16. ^ "Figuring How to Terrify Us Over Swine Flu" Townhall, July 30, 2009
  17. ^ "WHO chief warns H1N1 swine flu likely to worsen". Intellasia. May 23, 2009.
  18. ^ "Managing and Reducing Uncertainty in an Emerging Influenza Pandemic" New England Journal of Medicine, July 9, 2009
  19. ^ a b "New virus "very unstable", more changes seen-expert". Reuters. May 12, 2009.
  20. ^ "Avian Influenza Disease Emergency Situation Update" (PDF). FAO. July 25, 2008.
  21. ^ Steve Sternberg (May 26, 2009). "CDC expert says flu outbreak is dying down – for now".
  22. ^ "CDC says no sign yet that swine flu is mutating" Associated Press, July 23, 2009
  23. ^ "Chile confirms swine flu in turkeys" Associated Press, Aug. 21, 2009
  24. ^ Jordans, Frank (2009-04-30). "WHO to stop using term 'swine flu' to protect pigs". guardian.co.uk. Associated Press. Retrieved 2009-08-17.
  25. ^ "Transcript of virtual press conference with Dr Keiji Fukuda, Assistant Director-General ad Interim for Health Security and Environment, World Health Organization" (PDF). World Health Organization. 7 July 2009. Retrieved 2009-07-09.
  26. ^ "Novel H1N1 Flu (Swine Flu) and You". Centers for Disease Control and Prevention. 2009-08-05. Retrieved 2009-08-19.
  27. ^ "CDC Press Briefing Transcripts April 24, 2009". Centers for Disease Control and Prevention. April 24, 2009. Retrieved April 25, 2009.
  28. ^ "CDC says too late to contain U.S. flu outbreak". Reuters. 24 April 2009.
  29. ^ "Deadly new flu virus in U.S. and Mexico may go pandemic". New Scientist. April 28, 2009. Archived from the original on April 28, 2009. Retrieved April 28, 2009.
  30. ^ MacKenzie Debora (28 April 2009). "Deadly new flu virus in U.S. and Mexico may go pandemic". New Scientist. {{cite journal}}: Cite journal requires |journal= (help)
  31. ^ Mark Stevenson (April 25, 2009). "U.S., Mexico battle deadly flu outbreak". Associated Press.
  32. ^ Roos Robert (2007-12-20). "New swine flu virus supports 'mixing vessel' theory". Center for Infectious Disease Research and Policy (CIDRAP). Retrieved 2009-05-01.
  33. ^ Thacker E, Janke B (2008). "Swine influenza virus: zoonotic potential and vaccination strategies for the control of avian and swine influenzas". J Infect Dis. 197 Suppl 1: S19–24. doi:10.1086/524988. PMID 18269323. {{cite journal}}: Unknown parameter |month= ignored (help)
  34. ^ Hilleman M (19 August 2002). "Realities and enigmas of human viral influenza: pathogenesis, epidemiology and control". Vaccine. 20 (25–26): 3068–87. doi:10.1016/S0264-410X(02)00254-2. PMID 12163258.
  35. ^ Keim Brandon (28 April 2009). "Swine flu genes from pigs only, not humans or birds". Wired News.
  36. ^ McNeil Donald (30 April 2009). "Virus's tangled genes straddle continents, raising a mystery about its origins". New York Times.
  37. ^ Watts Susan (25 April 2009). "Experts concerned about potential flu pandemic". BBC News.
  38. ^ Dr. Henry Niman at FluTrackers has described the homologies of the genes as PB2 Avian North America, PB1 Human circa 1993, PA Swine Eurasia and/or North America, HA Swine North America, NP Swine Eurasia and/or North America, NA Swine Eurasia, MP Swine Eurasia, NS Swine Eurasia and/or North America.[1]
  39. ^ "Likely swine flu in Auckland New Zealand students". Recombinomics.com. 26 April 2009.
  40. ^ "Welcome to the GISAID Platform". GISAID is freely available, but subject to license terms. As of 8 May registration remained subject to a backlog of applications. Some discussion of sequence homologies can be found at "FluTracker.com".. The first strains released are A/California/09/2009 7M 2009-04-15, A/Texas/05/2009 16M 2009-04-15, A/Texas/04/2009 16M 2009-04-14, A/California/07/2009 54M 2009-04-09, A/California/06/2009 41F 2009-04-16, A/California/05/2009 9F 2009-03-30, and A/California/04/2009 10M 2009-04-01.
  41. ^ "Swine influenza A (H1N1) infection in two children --- Southern California, March--April 2009". MMWR. Centers for Disease Control and Prevention. 22 April 2009.
  42. ^ Emma Wilkinson (1 May 2009). "What scientists know about swine flu". BBC News.
  43. ^ Kirkey Sharon (6 May 2009). "Canadian lab completes sequencing of flu virus". Canwest News Service.
  44. ^ Galloway Gloria, Walton Dawn (6 May 2009). "Canadian, Mexican flu strains match". Toronto: The Globe and Mail.
  45. ^ Debora MacKenzie, New Scientist magazine, 2707 (9 May 2009), 4 "Preparing for the storm ahead". Text also available on website

External links

Retrieved from "https://en.wikipedia.org/w/index.php?title=Pandemic_H1N1/09_virus&oldid=310817967"