2009 swine flu outbreak

From Wikipedia, the free encyclopedia

Retrieved from "http://en.wikipedia.org/wiki/2009_swine_flu_outbreak" on 2009-05-02

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "2009 swine flu outbreak".

CONTENTS

Initial outbreaks

First recognition

Spread within Mexico

Seasonal variation

Genetics and effects

Genetics

Symptoms and severity

International cases and responses

Pandemic concern

WHO alert phases

Government actions against pigs and pork

Prevention and treatment

Name of the disease

Scientific name and common name

Debate over name

Reactions

Media Response

See also

References

External links

|  This article documents a current event. Information may change rapidly as the event progresses.
2009 swine flu outbreak - Cases by country
Detected cases by country
Last update: 2 May 2009 at 12:04 (UTC)

Country: Cases: Deaths:

Laboratory
confirmed: Suspectedâ€¡ (probable)[1]: Confirmed
(suspected)â€¡:

Totals  |  666  |  4,600+  |  17 (101)

Mexico  |  397[2]  |  2,500±[§][3]  |  16 (101)[4]

United States  |  162[5][6]  |  464 (312)[6]  |  1[7]

Canada  |  55[8]  |  25[9]  |  0

United Kingdom  |  15[10]  |  642 (2)[11]  |  0

Spain  |  13[12]  |  108[12]  |  0

Germany  |  6[13]  |  30[13]  |  0

New Zealand  |  4[14]  |  101 (12)[14]  |  0

Israel  |  3[15]  |  1[15]  |  0

France  |  2[16]  |  40 (1)[16]  |  0

Costa Rica  |  2[17]  |  51 (2)[18]  |  0

South Korea  |  1[19]  |  23 (1)[19]  |  0

Italy  |  1[20]  |  20+[21]  |  0

Switzerland  |  1[22]  |  17[22]  |  0

Hong Kong  |  1[23]  |  5[24]  |  0

Austria  |  1[10]  |  2[25]  |  0

Denmark  |  1[26]  |  0  |  0

Netherlands  |  1[27]  |  0  |  0

Other countries  |  0  |  322+ (9)  |  0

§ The Mexican government stopped reporting suspected cases and deaths on April 30, 2009.[3]
This table collects information from media reports regarding swine flu. It is not epidemiological data and so may suffer from one or more measurement biases.

Countries that have unconfirmed cases only:

Country: Probable[1]: Suspectedâ€¡ cases: Deaths: Confirmed
(suspected)â€¡:

Brazil  |  7[28]  |  41[28]  |  0

Sweden  |  1[29]  |  11[29]  |  0

Ireland  |  1[30]  |  0[30]  |  0

Australia  |  0  |  95[31]  |  0

Colombia  |  0  |  29[32]  |  0

Chile  |  0  |  26[33]  |  0

Czech Republic  |  0  |  20[34][35]  |  0

Argentina  |  0  |  13[36]  |  0

Bahamas  |  0  |  10[37]  |  0

Honduras  |  0  |  9[38]  |  0

Poland  |  0  |  9[39]  |  0

Peru  |  0[40]  |  7[40]  |  0

Belize  |  0  |  4[41]  |  0

Taiwan  |  0  |  4[42]  |  0

El Salvador  |  0  |  3[43]  |  0

Guatemala  |  0  |  3[44]  |  0

Singapore  |  0  |  3[45]  |  0

Venezuela  |  0  |  3[46]  |  0

India  |  0  |  3[47]  |  0

Barbados  |  0  |  2[37]  |  0

Russia  |  0  |  2[48][49]  |  0

Norway  |  0  |  1+[50][51]  |  0

Benin  |  0  |  1[52]  |  0

Japan  |  0  |  1[53]  |  0

Panama  |  0  |  1[54]  |  0

Uruguay  |  0  |  1[55]  |  0

Number of countries with confirmed cases: 16.

Number of countries with confirmed or suspected cases: 44.
â€¡ Suspected and probable cases have not been confirmed as being due to this strain of influenza by laboratory tests, although some other strains may have been ruled out.

v â€¢ d â€¢ e

The 2009 flu outbreak, commonly called the swine flu, is a spread of a new strain of influenza virus that was clinically identified in April 2009.[56] The new virus strain is a type of influenza A (H1N1) virus.[57] The outbreak has also been called the H1N1 influenza,[58] 2009 H1N1 flu,[59][60] Mexican flu,[61] or swine-origin influenza.[62] It is currently a level 5 outbreak, one level below an official pandemic.

Although the exact time and location of the outbreak is unknown, it is believed to have been first detected when an influenza-like illness was reported by both health agencies and local news media in Mexico. The virus responsible was clinically identified as a new strain on April 24, 2009. Within days, isolated cases (and suspected cases) were identified elsewhere in Mexico, the U.S., and several other countries. In late April officials from both WHO and the CDC expressed serious concern about the situation, stating that the virus had the potential to become a flu pandemic.[63]

By April 28, the new strain was confirmed to have spread to Spain, the United Kingdom, New Zealand, and Israel, and the virus was suspected in many other nations, with a total of over 4,400 candidate cases, prompting the World Health Organization (WHO) to change its pandemic alert phase to "Phase 5",[64] which is defined as "...human-to-human spread of the virus into at least two countries in one WHO region. By April 30, 300 schools had closed across the United States and the Mexican government ordered a multi-day shutdown of all non-essential activities in the government and private sector, amounting to a shutdown of most of the country's economy.[65] By late April, however, some virologists believed that this strain was unlikely to cause as many fatalities as earlier pandemics, and may not even be as damaging as a typical flu season.[66]

The new strain is an apparent reassortment of four strains of influenza A virus subtype H1N1.[67] Analysis at the United States Centers for Disease Control and Prevention (CDC) identified the four component strains as one endemic in humans, one endemic in birds, and two endemic in pigs (swine).[67] One swine strain was widespread in the United States, the other in Eurasia.[67] Although called swine flu due to it predominantly containing swine strains, the World Organisation for Animal Health have proposed the name North American influenza because this new strain in its entirety has not been found in swine (pigs).[68] Worldwide the common human H1N1 influenza virus affects millions of people every year, according to WHO officials, and "these annual epidemics result in about three to five million cases of severe illness, and about 250,000 to 500,000 deaths."[69] In industrialized countries most of these annual deaths occur in those 65 or older.[69]

Initial outbreaks
Further information: 2009 swine flu outbreak timeline
First recognition

The new strain of swine flu was first recognized as such when the CDC received a sample on April 14 from a patient who fell ill on March 30 in San Diego County, California. A second case was confirmed on April 17 who had fallen ill on March 28 in Imperial County, California.[70][71]

Spread within Mexico

The outbreak was first detected in Mexico City, where surveillance began picking up a surge in cases of influenza-like illness (ILI) starting March 18.[72] The surge was assumed by Mexican authorities to be "late-season flu" (which usually coincides with a mild Influenzavirus B peak)[73] until April 21,[74][75] when a U.S. Centers for Disease Control and Prevention alert concerning two isolated cases of a novel swine flu was reported in the media.[76] Some samples were sent to the U.S.-based CDC on April 18.[77] The Mexican cases were confirmed by the CDC and the World Health Organization to be a new strain of H1N1.[72][78]

Cases were also reported in the states of San Luis Potosí, Hidalgo, Querétaro and Mexico State.[79] Mexican Health Minister José Ángel Córdova on April 24, said "We’re dealing with a new flu virus that constitutes a respiratory epidemic that so far is controllable."[79]

The first death from swine flu occurred on April 13, when a diabetic woman from Oaxaca died from respiratory complications.[80][81] The Mexican fatalities are alleged to be mainly young adults of 25 to 45, a common trait of pandemic flu.[67][82] Although there have been reports of 152 "probable deaths"[83] in Mexico City and "more than 100 dead from swine flu",[84] the WHO had received reports of only 16 confirmed deaths total and explicitly denied the larger figure as of April 29.[85][86]

Seasonal variation

The high humidity of summer typically leads to the end of the flu season as the virus becomes less likely to spread. In Mexico City, May marks the end of the dry season, and experts speculate that the spread of the swine flu may slow.[87] On April 30 Mexican Health Secretary Jose Angel Cordova voiced cautious optimism that the spread of the swine flu might be slowing in that country.[88] However, the outbreak comes at the beginning of the flu season for Southern Hemisphere countries such as New Zealand, Australia, South Africa, and parts of South America.[89]

Genetics and effects

Genetics

Genetic origins of the 2009 swine flu outbreak[4]:

HA  |  Hemagglutinin  |  swine (H1)  |  North America

NA  |  Neuraminidase  |  swine (N1)  |  Europe

PA  |  Polymerase subunit A  |  avian  |  North America

PB1  |  Polymerase subunit B1, PB1-F2[90]  |  human  |  1993 H3N2 strain

PB2  |  Polymerase subunit B2  |  avian  |  North America

NP  |  Nucleoprotein  |  swine  |  North America

M  |  Matrix protein M1, M2  |  swine  |  Eurasia

NS  |  Non-structural proteins NS1, NEP  |  swine  |  North America

Source: La fiche d'identité d'un virus inédit, Lemonde.fr.  |   v â€¢ d â€¢ e

On April 24, the CDC determined that seven samples from suspected cases in Mexico matched the strain from California and Texas. Infecting patients in Texas and California with no known linkages to animals or one another, the strain appeared to be spreading from human to human.[91][63] 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."[67][92] A CDC investigative team arrived in Mexico City on April 25 to work with Mexican counterparts to study the virus.[74]

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.[93][94] Reassortment is a process that happens if two different types of influenza virus infects 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.[95] This new strain appears to be a result of the reassortment of two swine influenza viruses, one from North America and one from Europe.[96] 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.[97] These genes were passed on to the new virus.[98][99]

Gene sequences for every viral gene were made available through the Global Initiative on Sharing Avian Influenza Data (GISAID).[100][101] 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.[102] Preliminary analysis also reveals that the NS1 protein at the center of the virus - a protein responsible for the severity of the immune response produced by the virus- does not seem unusual. This suggests that the virus is unlikely to trigger severe cytokine storms similar to those caused by the 1918 pandemic flu virus.[103] So far, little is known about the spread of the virus in any pig population. As of April 30 an international team led Juan Lubroth, chief of veterinary investigations for the United Nations Food and Agriculture Organization, in coordination with researchers from the WHO, were in Mexico on the way to La Gloria, in pursuit of what has been dubbed "Pig Zero".[97]

The seasonal influenza strain H1N1 vaccine is thought to be unlikely to provide protection.[104] The virus was also resistant to amantadine and rimantadine, but susceptible to oseltamivir (Tamiflu) and zanamivir (Relenza).[105][106] Prelimenary genetic analyses of A(H1N1) suggests that it is a "fairly mild" flu virus, albeit subject to unpredictable mutations.[107]

Human swine flu symptoms[108]
See also: "Symptoms of swine flu on YouTube". Centers for Disease Control and Prevention. http://www.youtube.com/watch?v=0wK1127fHQ4.

Symptoms and severity

See also: Swine_influenza#In_humans, for symptoms in previous cases.

The CDC does not fully understand why the U.S. cases' symptoms were primarily mild disease while the Mexican cases had led to multiple deaths. However, research on previous pandemic strains has suggested that mortality can vary widely between different countries, with mortality being concentrated in the developing world.[109] Differences in the viruses or co-infection are also being considered as possible causes. In 1918, the 1918 influenza weakened the infected people, and it was then lung infections such as pneumonia which killed 3% of them. Such co-infection can be reduced by the use of antibiotics. In the current outbreak, the first death (13 and 21th April) were diagnosed as 'atypical pneumonias', a pneumonia which, helped by the flu, becomes more dangerous. The CDC's flu chief Nancy Cox said that genetic analysis of the swine flu strain did not reveal the markers for virulence found in the 1918 flu virus.[110]

At a press briefing on April 27, acting CDC director Dr. Richard Besser stated that out of 40 confirmed cases in the United States at that point, only one individual was hospitalized. He also revealed that the median age was 16 years "with a range in age of 7 to 54 years."[111] By April 29, the U.S. had 91 confirmed cases with 5 hospitalizations and one death.[112]

Whereas most influenza strains affect the elderly and young children worst, this strain has primarily caused deaths in people between the ages of 25 and 50.[113]

International cases and responses

Confirmed cases followed by death     Confirmed cases     Unconfirmed or suspected cases See also: Live map of swineflu, H1N1 live map

The new strain has spread widely beyond Mexico, with confirmed cases in fourteen countries and suspected cases in more than forty. Many countries have advised their inhabitants not to travel to infected areas.[weasel words] Countries including Australia, China, Iceland, India, Indonesia, Malaysia, Philippines, Singapore, South Korea and Thailand are monitoring visitors returning from flu-affected areas to identify people with fever and respiratory symptoms. Many countries have also issued warnings to visitors of flu-affected areas to contact a doctor immediately if they had flu-like symptoms.

Mexico's schools, universities, and all public events will be closed from April 24, 2009 to May 6, 2009.[114][115] On April 27, 2009, a few schools in the U.S. closed due to confirmed cases in students.[116][117][118]

Pandemic concern
See also: Pandemic Severity Index
WHO and CDC officials are concerned that this outbreak may become a pandemic, for the following reasons:[63]

- New strain

The virus is a new strain of influenza, from which human populations have not been vaccinated or naturally immunized.[119] In the United States, cases infected 25% of family members. Seasonal flu tends to sicken 5% to 20% of family members.[120]

- Widespread human transmission

The virus infects by human-to-human transmission. Investigations of infected patients indicated no direct contact with swine, such as at a farm or agricultural fair.[78] The strain was later confirmed to have been transmitted between humans.[121] In contrast, for example, disease transmission in the last severe human outbreak of influenza, the bird flu that peaked in 2006, was determined to be almost entirely from direct contact between humans and birds.[citation needed]

- Virulence

For reasons not yet well understood, all but one of the fatalities to date have been in Mexico. Furthermore, in Mexico (but not elsewhere) the reported deaths from the illness have primarily been young, healthy adults.[122] Most other influenza strains produce the worst symptoms in young children, the elderly, and others with weaker immune systems.[78][123] However, the CDC has indicated that symptoms reported from this strain so far are similar to those of normal seasonal flu.[124] While some media outlets have speculated that this virus could cause a cytokine storm in patients,[122] there is presently no evidence for this hypothesis, with the CDC stating that there is "insufficient information to date about clinical complications of this variant of swine-origin influenza A (H1N1) virus infection."[124]

- Lack of data

That other crucial factors are still largely unknown, such as transmission rates and patterns (epidemicity) and effectiveness of current influenza treatments, combined with the innate unpredictability of influenza strains, means that reliable forecasts cannot be made.

As noted, predicting the size and severity of influenza outbreaks is a very inexact science. In 1976 the U.S. government incorrectly predicted a swine flu pandemic that never materialized.[125]

WHO officials observed that because there are "human cases associated with an animal influenza virus, and because of the geographical spread of multiple community outbreaks, plus the somewhat unusual age groups affected, these events are of high concern".[78]

By the end of April, however, some scientists believed that this strain was unlikely to cause as many fatalities as earlier pandemics, and may not even be as damaging as a typical flu season.[66]

WHO alert phases

Prior to the swine flu outbreak, the WHO worldwide pandemic alert was set at Phase 3 due to H5N1 avian flu, which spread widely in birds with occasional cases in humans.[127][128][129] A Phase 3 alert means that a new virus has been confirmed but there is no or limited evidence of human-to-human transmission - insufficient to sustain community-level outbreaks. The WHO decided not to raise the level of the worldwide pandemic alert after its first meeting, on April 25.[129]

Following the second meeting of the Emergency Committee on April 27, the pandemic alert level was raised to Phase 4.[130] Phase 4, "Sustained Human to Human Transmission," entails community-wide outbreaks.[126]

As of April 29, World Health Organization acting assistant director-general Dr. Keiji Fukuda stated:

“ [that the organization was] moving closer to Phase 5. What we are trying to do right now is make absolutely sure that we are dealing with sustained transmission in at least two or more countries.[131] ”

On April 29, the Emergency Committee had their third meeting,[132] and decided to raise the pandemic alert level to five,[133] the second-highest level, indicating that a pandemic is "imminent," and that human-to-human transmission cases have been recorded in multiple regions.[134] In Catalonia, officials confirmed the first European case of an infection in a person who had not (recently) traveled to Mexico, in a person whose girlfriend had done so, the second WHO region to experience intergenerational transmision of H1N1.[135][136]

Government actions against pigs and pork

Although there is no evidence that the virus is transmitted by food,[137] and influenza A viruses are generally not heat resistant,[137] some countries banned import and sale of pork products "as a precaution against swine flu".[138][139]

Despite the lack of any evidence that the virus is present in swine anywhere in the world, Egypt's parliament called for the nation's 250,000 pigs to be killed immediately,[140] a move the World Organization for Animal Health called "scientifically unjustified".[137] Several countries, including Serbia, China and Russia banned the import of pork products from North America in general as a response to the outbreak, despite assurances from the WHO that the disease is not spread through pork.[141] On April 29, the Egyptian Government decided to kill all 300,000 pigs in Egypt, despite none of them having been suspected to be infected. [142][143]

Prevention and treatment
Further information: Influenza: Prevention and Influenza treatment
Recommendations to prevent infection by the virus consist of the standard personal precautions against influenza. This includes frequent washing of hands with soap and water or with alcohol-based hand sanitizers, especially after being out in public. The CDC advises not touching the mouth, nose or eyes, as these are primary modes of transmission. When coughing, they recommend coughing into a tissue and disposing of the tissue, then immediately washing the hands.[144]

There is no risk of flu transmission from the consumption of properly-cooked pork products.[145]

The previously recommended influenza vaccines for the southern and northern hemispheres, including that for the 2009/2010 flu season, are ineffective against the new strain.[146] Current development, large-scale manufacturing, distribution and delivery of a new vaccine takes several months.[147][148] The WHO Director-General announced that production of the unchanged seasonal vaccine should continue for now, and that the WHO would assist the development process for an effective vaccine.[130] U.S.-based medical product company Baxter International has requested a virus sample from the WHO in order to begin development of a new vaccine.[149] Sanofi-Aventis (Sanofi-Pasteur) is manufacturing the conventional seasonal flu vaccine and has not been asked to produce a vaccine against the new H1N1 strain, which would be difficult to manufacture without diverting facilities from current production.[150]

Of the available antiviral treatments for influenza, the WHO stated that the viruses obtained from the human cases with swine influenza in the United States were sensitive to oseltamivir (Tamiflu)[151] and zanamivir (Relenza) but resistant to amantadine and rimantadine.[152] Tamiflu and Relenza also have a preventative effect against Influenzavirus A.[153] On April 27, the CDC recommended the use of Tamiflu and Relenza for both treatment and prevention of the new strain.[154] Roche and the U.S. government had already extended the shelf life of federally stockpiled Tamiflu from the original five years to seven years because studies indicated that the medication continues to maintain its effectiveness.[155]

Due to a more convenient method of administration, treatment with oseltamavir is typically preferred, but in H3N2 flu treatment leads to resistance in 0.4% of adult cases and 5.5% of children. The resistant strains are typically less transmissible, but that is not certain, and resistant human H1N1 viruses have become widely established. Fortunately, simulations reveal that using a second effective antiviral such as zanamivir (Relenza) to treat even 1% of cases will delay the spread of resistant strains. Even a drug such as amantadine (Symmetrel) for which resistance frequently emerges may be useful in combination therapy.[156][157]

Train commuters in Mexico City wearing surgical masks

There is so far little data available on the risk of airborne transmission of this particular virus. Mexican authorities are distributing surgical masks to the general public. The UK Health Protection Agency considers facial masks unnecessary for the general public.[158] Many authorities recommend the use of respirators by health-care workers in the vicinity of pandemic flu patients, in particular during aerosol generating procedures (e.g. intubation, chest physiotherapy, bronchoscopy).

On April 28, Dr. Keiji Fukuda, the Assistant Director-General for Health Security and Environment of WHO, pointed out that it is too late to contain the swine flu. "Containment is not a feasible operation. Countries should now focus on mitigating the effect of the virus," he said.[83] He also stressed that the experts did not recommend closing borders or restricting travel. "With the virus being widespread... closing borders or restricting travel really has very little effects in stopping the movement of this virus."[83] However, on April 28, the U.S. CDC began "recommending that people avoid non-essential travel to Mexico."[159] The WHO's early reaction was that it saw no need at this point to issue travel advisories warning travellers not to go to parts of Mexico or the United States. The spokesperson said that the situation might change "depending on what the situation in the field is".[160] WHO Director-General Dr. Margaret Chan also said that it was too premature to issue such recommendations without better analysis and understanding of the situation at this stage.[161] Many countries confirmed that inbound international passengers will be screened. Typical airport health screening involves asking passengers which countries they have visited and checking whether they feel or appear particularly unwell. Thermographic equipment was put into use at a number of airports to screen passengers. In the USA, two confirmed cases were detected through their border infectious disease surveillance.[147] A number of countries advised against travel to known affected regions.

Dr. Ira Longini, a specialist in the mathematical and statistical theory of epidemics, suggests that if those infected stay at home or seek medical care, public meeting places are closed, and anti-flu medications are made widely available, then in simulations the sickness is reduced by nearly two-thirds. "The name of the game is to slow transmission until a well-matched vaccine can be made and distributed. I am fairly optimistic we can do that".[162]

Name of the disease

Scientific name and common name

The standard scientific subtype and strain nomenclature gives influenza virus isolates names such as "A/California/09/2009(H1N1)-like",[163] which are too complex to achieve widespread use. For more information see the influenza article.

According to researchers cited by The New York Times, "based on its genetic structure, the new virus is without question a type of swine influenza, derived originally from a strain that lived in pigs".[164] This origin gave rise to the nomenclature "Swine flu", largely used by mass media in the first days of the epidemic. Despite this origin, the current strain is now a human-to-human issue, requiring no contact with swine. On April 30 the World Health Organization stated that no pigs in any country have been determined to have the illness, but farmers remain alert due to concerns that infected humans may pass the virus to their herds.[165]

Debate over name

Some authorities object to calling the flu outbreak "swine flu". U.S. Agriculture Secretary Tom Vilsack expressed concerns that this would lead to the misconception that pork is unsafe for consumption.[166] Israeli deputy health minister Yaakov Litzman proposed the name "Mexican flu" because Muslims and Jews consider pork to be unclean,[167] but the Israeli government retracted this proposal following Mexican complaints.[168] Although the South Korean Ministry for Food, Agriculture, Forestry and Fisheries asked the press to use the term “Mexican Virus” on April 29,[169] most of South Korean press and people prefer to use SI (short for Swine Influenza). Taiwanese authorities suggested the names “H1N1 flu” or “new flu”, which most local media now use.[170] The World Organization for Animal Health has proposed the name "North American influenza".[171] The European Commission uses the term "novel flu virus".[168]

The WHO announced they would refer to the new influenza virus as influenza A(H1N1) or "Influenza A (H1N1) virus, human"[168] as opposed to "swine flu", to avoid suggesting pork products carried a risk of causing infection.[172] They confirmed that you cannot contract Influenza A (H1N1) by eating any properly cooked pork products.[173]

Others such as Henry Niman of Recombinomics object to the name change: "It's clearly swine. It's a flu virus from a swine, there's no other name to call it."[174]

Reactions

Media Response

Since the outbreak began, there has been a week of near constant media attention.[175] When a health emergency was officially declared[citation needed], the story of the outbreak spread quickly through news networks.[176] Multiple news conferences were aired in the United States by government officials. By the next day, it was the main topic of discussion.[176]

Epidemiologists caution that the number of cases reported in the early days of an outbreak can be very inaccurate and deceptive.[177] This can be due to several causes, including selection bias, media bias, and incorrect reporting by governments.

One hypothetical selection bias in this situation pertains to authorities in different countries looking at different sets of patient populations. For example, doctors in Mexico may be concentrating on patients in hospitals, rather than the larger vulnerable population, which may in part explain the higher mortality recorded in the country.[177] Media bias in reporting swine flu cases and deaths may skew incidence maps based on these media reports. Countries with poor health care systems and poor laboratory facilities may take longer to identify suspected cases, analyse those cases, and report them. Passive data collection methodologies (waiting for the patient to arrive at a health care facility) are considered inferior to active data collection techniques (performing random stratified sampling) because of various forms of selection bias.[178]

Furthermore, if national governments and local health care services for whatever reason do not accurately report their own data on suspected cases and deaths this will produce a garbage in garbage out bias in conclusions drawn from such data by any agency downstream, whether private or governmental, the media or official. For example, World Health Organization accused China of under-reporting cases of SARS during the 2002 SARS outbreak.[179] Gathering accurate data for the flu outbreak is further complicated by the possibility of further mutations of the virus,[180] and because laboratory facilities to perform swift genetic tests on patient samples are not widely available.[177]

See also

- 1976 swine flu outbreak

- 1918 flu pandemic (Spanish flu)

- Hong Kong Flu (1968–1969)

- Influenza pandemic

- Severe acute respiratory syndrome (SARS)

- Health care in Mexico

References

1. ^ [a] [b] "WHO case classification". WHO. 2009-04-29. http://www.who.int/csr/disease/swineflu/WHO_case_definition_swine_flu_2009_04_29.pdf. Retrieved on 2009-04-30.

2. ^ http://www.who.int/csr/don/2009_05_02/en/

3. ^ [a] [b] "Mexico: Number of new swine flu cases stabilizing". AP. 2009-04-30. http://www.google.com/hostednews/ap/article/ALeqM5gfYcVCw5PiKbk5yaX7JaF9NqhPygD97SVQV02. Retrieved on 2009-04-30.

4. ^ "Flu death toll 'less than feared'". BBC News Online. 2009-05-02. http://news.bbc.co.uk/1/hi/world/americas/8030365.stm. Retrieved on 2009-05-02.

5. ^ Thomas H. Maugh II (2 May 2009). "Parts of U.S. on hold as swine flu cases climb to 162". Los Angeles Times. http://www.latimes.com/features/health/la-sci-swineflu2-2009may02,0,6925163.story.

6. ^ [a] [b] See table at 2009 swine flu outbreak in the United States for references for potential cases.

7. ^ "Influenza A(H1N1) - update 8.1". World Health Organization. 1 May 2009. http://www.who.int/csr/don/2009_05_01a/en/index.html.

8. ^ "More cases of swine flu confirmed across Canada". CBC News. http://www.cbc.ca/canada/story/2009/05/01/swine-flu.html. Retrieved on 2009-05-01.

9. ^ See table at 2009 swine flu outbreak in Canada for references for potential cases.

10. ^ [a] [b] "ECDC Situation Report 02 May 2009". ECDC. 2009-05-02. http://ecdc.europa.eu/en/files/pdf/Health_topics/Situation_Report_020509.pdf. Retrieved on 2009-05-02.

11. ^ "Update on confirmed swine flu cases in England". Health Protection Agency. 1 May 2009. http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1241180227456.

12. ^ [a] [b] "La OMS niega que exista evidencia de transmisión sostenida entre personas en España" (in Spanish). Público (Spain). 2009-05-01. http://www.publico.es/espana/222538/numero/casos/sospechosos/espana/eleva. Retrieved on 2009-05-01.

13. ^ [a] [b] "Zweite Mensch-zu-Mensch-Infektion in Deutschland" (in German). 2009-05-02. http://www.spiegel.de/wissenschaft/natur/0,1518,622442,00.html. Retrieved on 2009-05-02.

14. ^ [a] [b] "Influenza A (H1N1) Swine Flu - Update Nineteen". New Zealand Ministry of Health. http://www.moh.govt.nz/moh.nsf/indexmh/influenza-a-h1n1-update-nineteen-020509. Retrieved on 2009-05-02.

15. ^ [a] [b] "3rd case of swine flu diagnosed in Israel". The Associated Press. 2009-05-02. http://www.ynetnews.com/articles/0,7340,L-3709377,00.html. Retrieved on 2009-05-02.

16. ^ [a] [b] "Grippe A : deux cas avérés en France" (in French). Le Figaro. 2009-05-01. http://www.lefigaro.fr/sante/2009/04/29/01004-20090429ARTFIG00067-h1n1-le-mexique-revoit-a-la-baisse-le-nombre-de-deces-.php. Retrieved on 2009-05-01.

17. ^ "Total Swine Flu Cases Worldwide, Also Countries With Confirmed Cases Of Secondary Transmission - 1 May 2009". Medical News Today.. 2009-05-01. http://www.medicalnewstoday.com/articles/148487.php. Retrieved on 2009-05-02.

18. ^ Costa Rica rules out 125 suspected cases of A/H1N1 flu

19. ^ [a] [b] >"ì‹ ì¢…í”Œë£¨ ì²« ê°�ì—¼ìž� í™•ì�¸". Nocut News. http://media.daum.net/society/cluster_list.html?clusterid=10477. Retrieved on 2009-05-02.

20. ^ "Italy confirms first case of new flu virus". Reuters. 2009-05-02. http://www.alertnet.org/thenews/newsdesk/L2543842.htm. Retrieved on 2009-05-02.

21. ^ "About 20 suspected cases of swine flu monitored in Italy". Xinhua. 30 April 2009. http://news.xinhuanet.com/english/2009-04/30/content_11284403.htm.

22. ^ [a] [b] "Aktueller Situationsbericht des Bundesamtes für Gesundheit (BAG): Neuer Influenza A/H1N1-Stamm". Bundesamt für Gesundheit (Federal Office of Public Health). 2009-05-01. http://www.bag.admin.ch/influenza/06411/index.html?lang=de&download=M3wBPgDB/8ull6Du36WcnojN14in3qSbnpWZaXCZnE6p1rJgsYfhyt3NhqbdqIV+baqwbKbXrZ6lhuDZz8mMps2go6fo. Retrieved on 2009-05-02.

23. ^ "Asia's first swine flu case reported in Hong Kong". The Guardian. 2009-05-01. http://www.guardian.co.uk/world/2009/may/01/mexico-economic-shutdown. Retrieved on 2009-05-01.

24. ^ "Update on swine influenza infection in humans". Surveillance and Epidemiology Branch of the Centre for Health Protection. 2009-05-02. http://www.chp.gov.hk/files/pdf/Daily_update_on_swine_influenza_bilingual.pdf. Retrieved on 2009-05-02.

25. ^ "Austria confirms 1st case of swine flu". Xinhua. 2009-04-30. http://en.chinagate.cn/features/swineflu/2009-04/30/content_17703229.htm. Retrieved on 2009-05-02.

26. ^ "First Dane confirmed with flu virus". The Copenhagen Post Online. 2009-05-01. http://www.cphpost.dk/news/national/88-national/45564-first-dane-confirmed-with-flu-virus.html. Retrieved on 2009-05-01.

27. ^ "Dutch confirm swine flu case in three year-old". Reuters. 2009-04-30. http://www.reuters.com/article/europeCrisis/idUSAAT007741. Retrieved on 2009-04-30.

28. ^ [a] [b] "Ocorrências de casos humanos de influenza A (H1N1)" (in Portuguese). Brasília: Ministry of Health of Brazil. 1 May 2009. http://189.28.128.100/portal/aplicacoes/noticias/default.cfm?pg=dspDetalheNoticia&id_area=124&CO_NOTICIA=10144. Retrieved on 1 May 2009.

29. ^ [a] [b] "Inkomna prover till SMI" (in Swedish). Smittskyddsinstitutet. http://www.smittskyddsinstitutet.se/svininfluensa/analys-av-svininfluensa/. Retrieved on 2009-05-02.

30. ^ [a] [b] "No further probable cases swine flu in Ireland". The Irish Times. 2009-05-01. http://www.irishtimes.com/newspaper/breaking/2009/0501/breaking4.htm. Retrieved on 2009-05-01.

31. ^ aap (2009-05-02). "Aus swine flu outbreak probable - Roxon". The Australian. http://www.theaustralian.news.com.au/story/0,25197,25418365-12377,00.html. Retrieved on 2009-05-02.

32. ^ "Tres nuevas sospechas del virus en Colombia" (in Spanish). El espectador. 1 May 2009. http://www.elespectador.com/articulo138794-van-15-muertos-y-343-contagiados-gripe-ah1n1. Retrieved on 2009-05-01.

33. ^ "Minsal eleva a 26 los potenciales afectados por gripe porcina". El Mercurio Online. http://www.emol.com/noticias/nacional/detalle/detallenoticias.asp?idnoticia=355877. Retrieved on 2009-04-29.

34. ^ "Infections of novel influenza virus A(H1N1), Update 29 April 2009, 08:00 hours CET". ECDC. 2009-04-27. http://ecdc.europa.eu/en/files/pdf/Health_topics/Situation_Report_290409-0830.pdf. Retrieved on 2009-04-27.

35. ^ "V domácí izolaci je po návratu z Mexika u~ 20 lidí". ct24.cz. 2009-04-30. http://www.ct24.cz/domaci/53348-v-domaci-izolaci-je-po-navratu-z-mexika-uz-20-lidi/. Retrieved on 2009-04-30.

36. ^ "En el país hay 13 casos sospechosos en estudio". 2009-04-29. http://www.lanacion.com.ar/nota.asp?nota_id=1123873. Retrieved on 2009-04-29.

37. ^ [a] [b] "Suspected swine flu cases in Caribbean as WHO raises alert level". Caribbean360. 30 April 2009. http://www.caribbean360.com/News/Caribbean/Stories/2009/04/30/NEWS0000007287.html.

38. ^ "Confirman 1er. caso de influenza tipo A en Honduras". 2009-04-30. http://www.laprensahn.com/Especiales/Ediciones/2009/04/30/Noticias/Confirman-1er.-caso-de-influenza-tipo-A-en-Honduras. Retrieved on 2009-04-30.

39. ^ "Stan na dzieD 1 maja 2009 r. z godziny 6:00". 2009-05-01. http://www.pzh.gov.pl/page/index.php?id=956. Retrieved on 2009-05-01.

40. ^ [a] [b] "Sin liderazgo frente a la pandemia". El Comercio. 2009-04-30. http://www.elcomercio.com.pe/impresa/notas/sin-liderazgo-frente-pandemia/20090501/280780. Retrieved on 2009-04-30.

41. ^ "Looming Pandemic. Swine Flu stirs fear". 2009-04-30. http://www.reporter.bz/index.php?option=content&task=view&id=3508&Itemid=2. Retrieved on 2009-04-30.

42. ^ "Four suspected swine flu cases under investigation: Taiwan DOH". May 1, 2009. http://www.etaiwannews.com/etn/news_content.php?id=935886&lang=eng_news&cate_img=49.jpg&cate_rss=news_Society_TAIWAN. Retrieved on 2009-05-01.

43. ^ "País en emergencia y hay tres casos sospechosos" (in Spanish). 2009-04-27. http://www.elsalvador.com/mwedh/nota/nota_completa.asp?idCat=6364&idArt=3586764. Retrieved on 2009-04-28.

44. ^ "La Prensa: Asciende a tres los casos sospechos de gripe porcina en Guatemala" (in Spanish). Prensa Libra. 2009-04-27. http://www.laprensahn.com/Ediciones/2009/04/27/Noticias/Asciende-a-tres-los-casos-sospechos-de-gripe-porcina-en-Guatemala. Retrieved on 2009-04-27.

45. ^ "3 more S'poreans tested". Straits Times. 2009-05-01. http://www.straitstimes.com/Breaking%2BNews/Singapore/Story/STIStory_371195.html. Retrieved on 2009-05-02.

46. ^ "Gripe porcina: Venezuela informa de tres casos sospechosos en el centro del país" (in Spanish). El Economista. 2009-04-27. http://ecodiario.eleconomista.es/internacional/noticias/1203507/04/09/Gripe-porcina-Venezuela-informa-de-tres-casos-sospechosos-en-el-centro-del-pais-.html. Retrieved on 2009-04-27.

47. ^ "Swine flu arrives in Asia; 3 suspected cases in Delhi". ET Bureau & Agencies. 2009-05-02. http://economictimes.indiatimes.com/News/PoliticsNation/Swine-flu-arrives-in-Asia-3-suspected-cases-in-Delhi/articleshow/4474677.cms. Retrieved on 2009-05-02.

48. ^ "Ð¡ÐœÐ˜: Ñ� Ð¿Ð¾Ð´Ð¾Ð·Ñ€ÐµÐ½Ð¸ÐµÐ¼ Ð½Ð° Ñ�Ð²Ð¸Ð½Ð¾Ð¹ Ð³Ñ€Ð¸Ð¿Ð¿ Ð³Ð¾Ñ�Ð¿Ð¸Ñ‚Ð°Ð»Ð¸Ð·Ð¸Ñ€Ð¾Ð²Ð°Ð½Ð° Ñ�ÐµÐ¼ÑŒÑ� Ð¼Ð¾Ñ�ÐºÐ²Ð¸Ñ‡ÐµÐ¹. Ð’Ð»Ð°Ñ�Ñ‚Ð¸ Ð¿Ð¾Ð´Ñ‚Ð²ÐµÑ€Ð´Ð¸Ð»Ð¸ Ñ‚Ð¾Ð»ÑŒÐºÐ¾ Ð¿Ñ€Ð¾ Ð´Ð²ÑƒÑ… Ð¶ÐµÐ½Ñ‰Ð¸Ð½" (in Russian). newsru.com. 2009-05-01. http://newsru.com/russia/01may2009/family.html. Retrieved on 2009-05-01.

49. ^ "Ð§ÐµÑ‚Ð²ÐµÑ€Ð¾ Ð¼Ð¾Ñ�ÐºÐ²Ð¸Ñ‡ÐµÐ¹ Ð² Ð±Ð¾Ð»ÑŒÐ½Ð¸Ñ†Ðµ Ñ� Ð¿Ð¾Ð´Ð¾Ð·Ñ€ÐµÐ½Ð¸ÐµÐ¼ Ð½Ð° Ñ�Ð²Ð¸Ð½Ð¾Ð¹ Ð³Ñ€Ð¸Ð¿Ð¿" (in Russian). Life.ru. 2009-05-01. http://life.ru/news/74655. Retrieved on 2009-05-01.

50. ^ Sindre Granly Meldalen, Arnhild Aass Kristiansen and Ragnhild Avdem Fretland (2009-04-28). "Det er åtte-ti mistenkte i Norge" (in Norwegian). http://www.dagbladet.no/2009/04/28/nyheter/innenriks/svineinfluensa/folkehelseinstituttet/5958960/. Retrieved on 2009-04-28.

51. ^ Kristin Agerlie (30 April 2009). "Ingen smitta ved St. Olav". NRK (Norwegian Broadcasting Corporation). http://nrk.no/nyheter/distrikt/nrk_trondelag/1.6589484.

52. ^ "Benin Confirms Africa's Second Suspected Swine-Flu Case" (in English). Dow Jones News Wire. 2009-05-02. http://www.beurs.nl/nieuws/artikel.php?id=291085&taal=US. Retrieved on 2009-05-02.

53. ^ Staff writer (2009-05-02). "Baby at Yokota base latest flu scare focus". Japan Times. http://search.japantimes.co.jp/cgi-bin/nn20090502a1.html. Retrieved on 2009-5-02.

54. ^ Manuel Vega Loo (2009-04-30). "Analizan caso sospechoso de gripe porcina". Prensa. http://mensual.prensa.com/mensual/contenido/2009/04/28/uhora/local_2009042806551776.asp. Retrieved on 2009-04-30.

55. ^ Staff writer (2009-04-28). "Influenza: Aparece primer presunto infectado en Uruguay" (in Spanish). El Universal. http://www.eluniversal.com.mx/notas/594224.html. Retrieved on 2009-04-28.

56. ^ "Swine flu timeline". http://biosurveillance.typepad.com/biosurveillance/2009/04/swine-flu-in-mexico-timeline-of-events.html.

57. ^ "Influenza A(H1N1)". World Health Organization. 30 April 2009. http://www.who.int/csr/disease/swineflu/en/index.html. Retrieved on April 30, 2009.

58. ^ "WHO changes swine flu name to 'H1N1 influenza'". HT Media Limited. 30 April 2009. http://www.hindustantimes.com/StoryPage/StoryPage.aspx?sectionName=Cricket&id=763ce0b9-923f-445b-bdd8-e31fb051270a&Headline=WHO+changes+swine+flu+name+to+%27H1N1+influenza%27%2c+257+confirmed+cases.

59. ^ "Ni porcina ni mexicana, la OMS bautiza la gripe como «H1»". ABC.es. 1 May 2009. http://www.abc.es/20090501/nacional-sociedad/porcina-mexicana-bautiza-gripe-20090501.html.

60. ^ "Name dilemma: Swine flu or Mexican flu?". IndiaTimes. 30 April 2009. http://timesofindia.indiatimes.com/India/Name-dilemma-Swine-flu-or-Mexican-flu/articleshow/4464770.cms.

61. ^ . Radio Netherlands. 29 April 2009. http://www.radionetherlands.nl/news/international/6280110/WHOs-call-new-strain-of-H1N1-Mexican-flu.

62. ^ "Update: infections with a swine-origin influenza A (H1N1) virus --- United States and other countries". Morbidity and Mortality Weekly Report (U.S. Centers for Disease Control). 28 April 2009. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm58d0428a2.htm.

63. ^ [a] [b] [c] "CDC Press Briefing Transcripts April 24, 2009". Centers for Disease Control and Prevention. 24 April 2009. http://www.cdc.gov/media/transcripts/2009/t090424.htm. Retrieved on 2009-04-25.

64. ^ "Swine influenza". World Health Organization. 29 April 2009. http://www.who.int/entity/mediacentre/news/statements/2009/h1n1_20090429/en/index.html. Retrieved on 2009-04-30.

65. ^ Staff writer (29 April 2009). "Mexico to shut down government in flu fight". MSNBC. http://www.msnbc.msn.com/id/30487509/. Retrieved on 2009-04-30.

66. ^ [a] [b] "Scientists see this flu strain as relatively mild". Los Angeles Times. 2009-04-30. http://www.latimes.com/features/health/la-sci-swine-reality30-2009apr30,0,3606923.story. Retrieved on 2009-05-01.

67. ^ [a] [b] [c] [d] [e] "Deadly new flu virus in U.S. and Mexico may go pandemic". New Scientist. 28 April 2009. Archived from the original on 2009-04-28. http://www.webcitation.org/5gNd9HTT9. Retrieved on 2009-04-28.

68. ^ World Organisation for Animal Health (April 29, 2009). A/H1N1 influenza like human illness in Mexico and the USA: OIE statement. Press release. http://www.oie.int/eng/press/en_090427.htm. Retrieved on April 29, 2009.

69. ^ [a] [b] "Influenza (seasonal)". World Health Organization. 2009-04-30. http://www.who.int/mediacentre/factsheets/fs211/en/index.html. Retrieved on 2009-04-30.

70. ^ "Swine influenza A (H1N1) infection in two children --- Southern California, March--April 2009". Morbidity and Mortality Weekly Report. Centers for Disease Control. 22 April 2009. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5815a5.htm.

71. ^ David Brown (April 22, 2009). "New strain of swine flu investigated: two children in San Diego area had no contact with pigs". Washington Post. http://www.washingtonpost.com/wp-dyn/content/article/2009/04/21/AR2009042103694.html. Retrieved on April 24, 2009.

72. ^ [a] [b] "Q&A: Swine flu.". BBC News. http://news.bbc.co.uk/2/hi/health/8017585.stm.

73. ^ McNeil Jr., Donald G. (2009-04-26). "Flu outbreak raises a set of questions". New York Times. http://www.nytimes.com/2009/04/27/health/27questions.html. Retrieved on 2009-04-26.

74. ^ [a] [b] Mark Stevenson (2009-04-25). "U.S., Mexico battle deadly flu outbreak". Associated Press. http://www.komonews.com/news/national/43692847.html.

75. ^ Brown David (26 April 2009). "U.S. slow to learn of Mexico flu". Washington Post. http://www.washingtonpost.com/wp-dyn/content/article/2009/04/25/AR2009042501335.html.

76. ^ Mike Stobbe (April 21, 2009). "Officials alert doctors after 2 California children infected with unusual swine flu". Associated Press. http://www.startribune.com/lifestyle/health/43357097.html?elr=KArks7PYDiaK7DUvDE7aL_V_BD77:DiiUiacyKUUr. Retrieved on April 24, 2009.

77. ^ "Grippe porcine: Mexico sous tension, le monde en alerte - Yahoo! Actualités". Fr.news.yahoo.com. http://fr.news.yahoo.com/3/20090426/twl-monde-grippe-porcine-1be00ca.html. Retrieved on 2009-04-27.

78. ^ [a] [b] [c] [d] "Influenza-Like Illness in the United States and Mexico". World Health Organization. 2009-04-24. http://www.who.int/csr/don/2009_04_24/en/index.html. Retrieved on 2009-04-25.

79. ^ [a] [b] Lacey, Marc; McNeil, Donald G. Jr. (April 24, 2009). "Fighting deadly flu, Mexico shuts schools". The New York Times. http://www.nytimes.com/2009/04/25/world/americas/25mexico.html.

80. ^ "El virus mutó en mujer de Oaxaca". El Universal. http://www.eluniversal.com.mx/nacion/167576.html. Retrieved on 2009-04-27.

81. ^ Orsi, Peter. "Mexico says suspected swine flu deaths now at 149". Associated Press. Archived from the original on 2009-04-28. http://www.webcitation.org/5gNf8rqeS. Retrieved on 2009-04-28.

82. ^ "World on alert as Mexico flu epidemic fear grows". Reuters. 2009-04-26. http://www.reuters.com/article/marketsNews/idUSN2648252220090426. Retrieved on 2009-04-26.

83. ^ [a] [b] [c] "'Too late' to contain swine flu". BBC News. 28 April 2009. http://news.bbc.co.uk/1/hi/world/americas/8021827.stm. Retrieved on 2009-04-28.

84. ^ "More than 100 dead from swine flu outbreak in Mexico". Herald Sun. April 27, 2009. http://www.news.com.au/heraldsun/story/0,21985,25392188-23109,00.html.

85. ^ "Only 7 swine flu deaths, not 152, says WHO". Sydney Morning Herald. April 29, 2009. http://www.smh.com.au/world/only-7-swine-flu-deaths-not-152-says-who-20090429-aml1.html. Retrieved on 2009-04-29.

86. ^ "WHO | Swine influenza - update 4". World Health Organization. http://www.who.int/csr/don/2009_04_28/en/index.html. Retrieved on 2009-04-29.

87. ^ John Roach (2009-04-30). "Summer to Kill Swine Flu in U.S. and Mexico?". National Geographic. http://news.nationalgeographic.com/news/2009/04/090430-swine-flu-summer.html.

88. ^ Paul Haven and Niko Price (2009-04-30). "Mexico's health chief hopeful swine flu has slowed". Associated Press. http://www.sfgate.com/cgi-bin/article.cgi?f=/n/a/2009/04/29/international/i194308D09.DTL&feed=rss.news.

89. ^ Oppman, Patrick (April 28, 2009). "Expert on flu's spread says new strain here to stay". CNN. http://www.cnn.com/2009/HEALTH/04/28/flu.computer.modeling/index.html. Retrieved on April 29, 2009.

90. ^ PB1-F2 is not present in this strain.Bruce Lieberman (2009-05-01). "Scientists studying genetics of flu strain". http://www3.signonsandiego.com/stories/2009/may/01/1n1strain00212-scientists-studying-genetics-flu-st/?nation.  Compare a human strain with the gene[1] to the equivalent nucleotides 95-367 of swine flu.[2]

91. ^ "CDC says too late to contain U.S. flu outbreak". Reuters. 2009-04-24. http://www.alertnet.org/thenews/newsdesk/24443479.htm.

92. ^ Debora MacKenzie (28 April 2009). Deadly new flu virus in US and Mexico may go pandemic. New Scientist. http://www.webcitation.org/5gNd9HTT9.

93. ^ Robert Roos (2007-12-20). "New swine flu virus supports 'mixing vessel' theory". Center for Infectious Disease Research and Policy (CIDRAP). http://www.cidrap.umn.edu/cidrap/content/influenza/avianflu/news/dec2007swine.html. Retrieved on 2009-05-01.

94. ^ Thacker E, Janke B (February 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.

95. ^ Hilleman, M (August 19 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.

96. ^ Brandon Keim (2009-04-28). "Swine flu genes from pigs only, not humans or birds". Wired News. http://www.wired.com/wiredscience/2009/04/swinefluupdate/.

97. ^ [a] [b] Donald McNeil (2009-04-30). "Virus’s Tangled Genes Straddle Continents, Raising a Mystery About Its Origins". New York Times. http://www.nytimes.com/2009/05/01/health/01origin.html.

98. ^ Susan Watts (2009-04-25). "Experts concerned about potential flu pandemic". BBC. http://www.bbc.co.uk/blogs/newsnight/susanwatts/2009/04/experts_concerned_about_potent.html.

99. ^ 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.[3]

100. ^ "Likely swine flu in Auckland New Zealand students". Recombinomics.com. 2009-04-26. http://www.recombinomics.com/News/04260901/H1N1_Swine_Aukland.html.

101. ^ "GISAID". http://platform.gisaid.org/dante-cms/live/struktur.jdante?aid=1131.  GISAID is freely available, but subject to license terms and currently subject to a backlog of applications following the outbreak. Some discussion of sequence homologies can be found at "FluTracker.com". http://www.flutrackers.com/forum/showthread.php?t=100610. . 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.

102. ^ "Swine Influenza A (H1N1) Infection in Two Children --- Southern California, March--April 2009". CDC MMWR. 2009-04-22. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5815a5.htm.

103. ^ Emma Wilkinson (2009-05-01). "What scientists know about swine flu". BBC. http://news.bbc.co.uk/2/hi/health/8028371.stm.

104. ^ "Update: Swine Influenza A (H1N1) Infections --- California and Texas, April 2009". CDC MMWR. 2009-04-24. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm58d0424a1.htm.

105. ^ "CDC briefing on public health investigation of human cases of swine influenza". CDC online newsroom. 2009-04-23. http://www.cdc.gov/media/transcripts/2009/t090423.htm.

106. ^ "Influenza-like illness in the United States and Mexico". WHO. 2009-04-24. http://www.who.int/csr/don/2009_04_24/en/index.html.

107. ^ Emma Wilkinson. "Health | What scientists know about swine flu". BBC News. http://news.bbc.co.uk/2/hi/health/8028371.stm. Retrieved on 2009-05-02.

108. ^ "Key facts about swine influenza (swine flu)". Centers for Disease Control and Prevention. http://www.cdc.gov/h1n1flu/key_facts.htm. Retrieved on 2009-04-27.

109. ^ Murray CJ, Lopez AD, Chin B, Feehan D, Hill KH (December 2006). "Estimation of potential global pandemic influenza mortality on the basis of vital registry data from the 1918–20 pandemic: a quantitative analysis". Lancet 368 (9554): 2211–8. doi:10.1016/S0140-6736(06)69895-4. PMID 17189032.

110. ^ "CDC: New Swine Flu Virus Lacks Genes Of 1918 Killer Flu". Associated Press. 2009-05-01. http://www.wjbf.com/jbf/news/national/article/cdc_new_swine_flu_virus_lacks_genes_of_1918_killer_flu/13244/.

111. ^ "CDC media availability on human swine influenza cases - April 27, 2009, 1 p.m. EST". Centers for Disease Control and Prevention. April 27, 2009. http://www.cdc.gov/media/transcripts/2009/t090427.htm. Retrieved on April 27, 2009.

112. ^ "CDC: swine flu cases climb to 91 in 10 states". FoxNews/AP. 29 April 2009. http://www.foxnews.com/politics/first100days/2009/04/29/obama-stay-home-youre-sick/.

113. ^ "Mexico increases closures as flu toll rises to 149 (Update4)". Bloomberg. 27 April 2009. http://www.bloomberg.com/apps/news?pid=20601086&sid=aH8DeSCFHnJY&refer=latin_america.

114. ^ "Mexican schools shut as epidemic hits 'critical' point". The Washington Post. 2009-04-27. http://www.washingtonpost.com/wp-dyn/content/article/2009/04/27/AR2009042702017.html. Retrieved on 2009-04-28.

115. ^ Tom Randall (April 29, 2009). "Swine flu kills child in Texas as virus spreads". Bloomberg. http://www.bloomberg.com/apps/news?pid=20601080&sid=aiUTjQxkoGZM&refer=asia. Retrieved on 2009-05-01.

116. ^ "Notice: Important updates regarding the temporary closure of all SCUC ISD campases from the superintendent". Schertz-Cibolo-Universal City Independent School District. http://www.scuc.txed.net/. Retrieved on 2009-05-01.

117. ^ "Home page". St. Francis Preparatory School Online. http://www.sfponline.org/. Retrieved on 2009-04-27.

118. ^ "Della Lindsey Elementary School closes by probable swine flu case, second local school to close after Indio High School's closure". Palm Springs, California: The Desert Sun. 2009-04-30. http://www.mydesert.com/article/20090430/NEWS08/904300334. Retrieved on 2009-04-30.

119. ^ "Morbidity and Mortality Weekly Report Dispatch". U.S. Centers for Disease Control. 21 April 2009. http://www.cdc.gov/mmwr/preview/mmwrhtml/mm58d0421a1.htm.

120. ^ "Sharper picture of swine flu virus outbreak begins to emerge". Associated Press. 2009-05-01. http://www.cbc.ca/health/story/2009/05/01/swine-flu-cdc.html.

121. ^ "Questions & Answers: Swine Influenza and You". Centers for Disease Control and Prevention. April 29, 2009. http://www.cdc.gov/h1n1flu/swineflu_you.htm. Retrieved on April 30, 2009.

122. ^ [a] [b] "Fighting deadly flu, Mexico shuts schools". New York Times. 24 April 2009. http://www.nytimes.com/2009/04/25/world/americas/25mexico.html?bl&ex=1240891200&en=ce91d53e13153eed&ei=5087.

123. ^ Stein Rob, Brown David (25 April 2009). "Swine flu found in Mexican outbreak". Washington Post. http://www.washingtonpost.com/wp-dyn/content/article/2009/04/24/AR2009042404075.html.

124. ^ [a] [b] "Interim guidance for clinicians on identifying and caring for patients with swine-origin influenza A (H1N1) virus infection". Centers for Disease Control. 29 April 2009. http://www.cdc.gov/h1n1flu/identifyingpatients.htm.

125. ^ Mike Stobbe (27 April 2009). "Swine flu's course unpredictable". Washington, D.C.: Express. p. 3.

126. ^ [a] [b] "WHO Pandemic Influenza Phases". Who.int. http://www.who.int/csr/disease/avian_influenza/phase/en/index.html. Retrieved on 2009-04-27.

127. ^ "Mexico Takes Powers to Isolate Cases of Swine Flu". The New York Times. 2009-04-25. http://www.nytimes.com/2009/04/26/world/americas/26mexico.html. Retrieved on 2009-04-26.

128. ^ "Suspected Mexico flu toll hits 81". BBC. 2009-04-26. http://news.bbc.co.uk/2/hi/americas/8018991.stm. Retrieved on 2009-04-26.

129. ^ [a] [b] "Current WHO phase of pandemic alert". WHO. http://www.who.int/csr/disease/avian_influenza/phase/en/index.html. Retrieved on 2009-04-26.

130. ^ [a] [b] Dr Margaret Chan (2009-04-27). "Swine influenza". World Health Organization. http://www.who.int/mediacentre/news/statements/2009/h1n1_20090427/en/index.html. Retrieved on 2009-04-27.

131. ^ "WHO considers raising alert level". Globe and Mail. 2009-04-29. http://www.theglobeandmail.com/servlet/story/RTGAM.20090429.wflumain0429/BNStory/International/home. Retrieved on 2009-04-29.

132. ^ Jordans, Frank; Maria Cheng (2009-04-29). "WHO calls emergency meeting; eyes pandemic level". Associated Press. Google News. Archived from the original on 2009-04-30. http://www.webcitation.org/5gQgjpMU0. Retrieved on 2009-04-30.

133. ^ "Statement by WHO Director-General, Dr Margaret Chan". 2009-04-29. http://www.who.int/mediacentre/news/statements/2009/h1n1_20090429/en/index.html. Retrieved on 2009-04-29.

134. ^ "WHO elevates pandemic threat level". CNN. 29 April 2009. http://www.cnn.com/2009/HEALTH/04/29/swine.flu/index.html.

135. ^ "Mexico begins five-day shutdown to fight swine flu - News - Muzi.com". Dailynews.muzi.com. http://dailynews.muzi.com/news/ll/english/10089979.shtml?q=&cc=10314&a=on. Retrieved on 2009-05-02.

136. ^ "CTV Toronto - WHO looking for signs of ongoing swine flu spread - CTV News, Shows and Sports - Canadian Television". Toronto.ctv.ca. 2009-04-28. http://toronto.ctv.ca/servlet/an/local/CTVNews/20090428/swineflu_WHO_090428/20090428?hub=TorontoNewHome. Retrieved on 2009-05-02.

137. ^ [a] [b] [c] World Organization for Animal Health (28 April 2009). OIE position on safety of international trade of pigs and products of pig origin. Press release. http://www.oie.int/eng/press/en_090428.htm. Retrieved on 2009-04-30.

138. ^ Binsal Abdul Kader (29 April 2009). "UAE bans import and sale of pork 'as a precaution against swine flu'". Gulf News. http://www.gulfnews.com/nation/Health/10308747.html.

139. ^ Mitya Underwood, Matt Kwong (30 April 2009). "UAE bars pork imports". The National (Abu Dhabi). http://www.thenational.ae/article/20090430/NATIONAL/704299799/1133.

140. ^ "Egyptians seek 'immediate death' for nation's pigs". Calgary Herald. 28 April 2009. http://www.calgaryherald.com/health/Egyptians+seek+immediate+death+nation+pigs/1541927/story.html.

141. ^ Jonathan Lynn (28 April 2009). "Russia, China ban pork imports from Mexico, US". Reuters. http://www.news.com.au/story/0,27574,25397431-23109,00.html.

142. ^ "Egyptian farmers forced to kill swine herds". Worldblog (MSNBC). 30 April 2009. http://worldblog.msnbc.msn.com/archive/2009/04/30/1915246.aspx. Retrieved on 2009-05-02.

143. ^ Maamoun Youssef. "Egypt orders slaughter of all pigs over swine flu". The Associated Press. Google. http://www.google.com/hostednews/ap/article/ALeqM5jc_pijXYi6E50wDepameI2ZTf9iAD97S7UPG2. Retrieved on 2009-05-02.

144. ^ "CDC H1N1 Flu". Centers for Disease Control and Prevention. http://www.cdc.gov/h1n1flu/. Retrieved on April 30, 2009.

145. ^ "Pork safe to eat despite swine flu concern". United Press International. UPI.com. April 28, 2009. http://www.upi.com/Science_News/2009/04/28/Pork-safe-to-eat-despite-swine-flu-concern/UPI-16451240931613/. Retrieved on April 29, 2009.

146. ^ "CDC Swine Flu FAQ". Centers for Disease Control and Prevention. http://www.cdc.gov/h1n1flu/key_facts.htm. Retrieved on 2009-04-27.

147. ^ [a] [b] "CDC Press Briefing Transcript - Media availability on CDC investigation of human cases of swine influenza". CDC. 25 APril 2009. http://www.cdc.gov/media/transcripts/2009/t090425.htm. Retrieved on 2009-04-26.

148. ^ "IL-based Baxter working on swine flu vaccine". AP. BusinessWeek. 2009-04-25. http://www.businessweek.com/ap/financialnews/D97PS9U81.htm. Retrieved on April 26, 2009.

149. ^ "Baxter to work to contain Mexico flu outbreak". Chicago Tribune. 2009-04-25. http://www.chicagotribune.com/business/chi-090425baxterswineflu-link,0,2879323.storylink. Retrieved on April 26, 2009.

150. ^ Howard Frank (2009-04-30). "Reports that Sanofi swine production would block seasonal flu vaccine premature". Pocono Record. http://www.poconorecord.com/apps/pbcs.dll/article?AID=/20090430/NEWS/90430006.

151. ^ "WHO says initial findings show swine flu responds to Tamiflu". NASDAQ. http://www.nasdaq.com/aspx/stock-market-news-story.aspx?storyid=200904251215dowjonesdjonline000319. Retrieved on 2009-04-25.

152. ^ "Swine influenza questions and answers" (PDF). World Health Organization. http://www.who.int/entity/csr/swine_flu/swineflu_qanda_20090425.pdf. Retrieved on 2009-04-26.

153. ^ "Tamiflu product information (prescribing information document)" (PDF). Roche Laboratories. August 2008. http://www.rocheusa.com/products/tamiflu/pi.pdf. Retrieved on 2009-04-26.

154. ^ "Antiviral Drugs and Swine Influenza". Centers for Disease Control and Prevention. April 29, 2009. http://www.cdc.gov/h1n1flu/antiviral.htm. Retrieved on April 30, 2009.

155. ^ "Mary Ann Liebert, Inc. - Biosecurity and Bioterrorism: Biodefense Strategy, Practice, and Science - 7(1):101". Liebertonline.com. doi:10.1089/bsp.2009.0011.. http://www.liebertonline.com/doi/abs/10.1089/bsp.2009.0011. Retrieved on 2009-04-27.

156. ^ Joseph T. Wu, Gabriel M. Leung, Marc Lipsitch, Ben S. Cooper, Steven Riley (2009-05-01). Hedging against Antiviral Resistance during the Next Influenza Pandemic Using Small Stockpiles of an Alternative Chemotherapy. PLOS. http://www.plos.org/press/plme-06-05-wu.pdf.  prepublication release

157. ^ Rob Waters (2009-04-30). "Relenza Should Be First Flu Drug Used, Study Says (Update1)". http://www.bloomberg.com/apps/news?pid=20601124&sid=adAvvB1lod_s&refer=home.

158. ^ UK Health Protection Agency (28 April 2009). Information for the media on face masks. Press release. http://www.hpa.org.uk/web/HPAweb&HPAwebStandard/HPAweb_C/1240899135838.

159. ^ "CDC - Travelers' Health - Travel Health Warning". Centers for Disease Control and Prevention. April 30, 2009. http://wwwn.cdc.gov/travel/contentSwineFluMexico.aspx. Retrieved on April 30, 2009.

160. ^ "WHO ready with antivirals to combat swine flu". Reuters. 2009-04-24. http://www.reuters.com/article/latestCrisis/idUSLO332728.

161. ^ "Virtual press briefing - swine influenza" (MP3). WHO. 25 April 2009. http://terrance.who.int/mediacentre/audio/press_briefings/VPC_25APR2009swine_influenza.mp3.

162. ^ "Expert: New strain of swine flu here to stay |West Palm Beach News, South Florida Breaking News, Forecast, Video from". WPTV. http://www.wptv.com/news/local/story/Swine-flu-expert-say-new-strain-here-to-stay/qTXTUuG2dkiegCHE5vBa8w.cspx. Retrieved on 2009-05-02.

163. ^ "Recommended composition of influenza virus vaccines for use in the 2009 southern hemisphere influenza season". World Health Organization. 2008-09-20. http://www.who.int/csr/disease/influenza/recommendations2009south/en/index.html. Retrieved on 2009-05-01.

164. ^ Andrew Martin, Clifford Krauss (April 28, 2009). "Pork industry fights concerns over swine flu". The New York Times. http://www.nytimes.com/2009/04/29/business/economy/29trade.html.

165. ^ Carey Gillam (1 May 2009). "US farmers fear pigs may get "swine" flu from people". Reuters. http://www.alertnet.org/thenews/newsdesk/N30269273.htm.

166. ^ "US looks to change 'swine flu' name". Agence France-Presse. 29 April 2009. http://www.google.com/hostednews/afp/article/ALeqM5gBhi-P53KpOUE54eBB88rlbMFXfg. Retrieved on 2009-04-29.

167. ^ "Israeli official: Swine flu name offensive". Associated Press. 28 April 2009. http://www.google.com/hostednews/ap/article/ALeqM5ieHZRubAS3lyjn2GBiCPkXkHrXwwD97QROAG0. Retrieved on 2009-04-29.

168. ^ [a] [b] [c] Pilkington, Ed (28 April 2009). "What's in a name? Governments debate 'swine flu' versus 'Mexican' flu". Guardian. http://www.guardian.co.uk/world/2009/apr/28/mexican-swine-flu-pork-name. Retrieved on 2009-04-29.

169. ^ "South Korea changed the name 'Swine flu' to 'Mexican Virus'". BCC (Taiwan). 29 April 2009. http://tw.news.yahoo.com/article/url/d/a/090429/1/1imtp.html.  (Traditional Chinese)

170. ^ "Renamed swine flu certain to hit Taiwan". The China Post. 29 April 2009. http://www.chinapost.com.tw/health/infectious-diseases/2009/04/29/206057/p2/Renamed-swine.htm.

171. ^ Bradsher, Keith (28 April 2009). "The naming of swine flu, a curious matter". New York Times. http://www.nytimes.com/2009/04/29/world/asia/29swine.html. Retrieved on 2009-04-29.

172. ^ "Epidemic and Pandemic Alert and Response (EPR)". World Health Organization. http://www.who.int/csr/disease/swineflu/en/index.html. Retrieved on 2009-05-01.

173. ^ "Joint FAO/WHO/OIE statement on influenza A(H1N1) and the safety of pork". World Health Organization. 30 April 2009. http://www.who.int/mediacentre/news/statements/2009/h1n1_20090430/en/index.html. Retrieved on 2009-05-01.

174. ^ Swine flu name change? Flu genes spell pig, Seth Borenstein, AP , April 30, 2009

175. ^ Childs, Dan and Donaldson, Susan. ABC News: "Swine Flu Snafu: Ernst & Young Episode Reveals Pandemic Panic". April 28, 2009.

176. ^ [a] [b] Kurtz, Howard. Newsday (from The Washington Post): "Media's coverage of swine flu is feverish". April 27, 2009.

177. ^ [a] [b] [c] Altman, Lawrence K (2009-04-28). "Sound the Alarm? A Swine Flu Bind". New York Times. http://www.nytimes.com/2009/04/28/health/28docs.html?hpw. Retrieved on 2009-04-30.

178. ^ "Observational Studies and Bias in Epidemiology". College board. 2004. http://www.collegeboard.com/prod_downloads/yes/4297_MODULE_19.pdf. Retrieved on April 30, 2009.

179. ^ "WHO accuses China of hiding SARS". The Cincinnati Post. April 16, 2003. http://www.highbeam.com/doc/1G1-100176015.html. Retrieved on April 30, 2009.

180. ^ Normile, Dennis (2009-04-30). "As Swine Flu Spreads, Its Chances to Mutate Increase". Science magazine. http://sciencenow.sciencemag.org/cgi/content/full/2009/429/1?rss=1. Retrieved on 2009-04-30.

External links

|  Wikimedia Commons has media related to: 2009 swine flu outbreak

|  Wikinews has related news: Swine flu

- Influenza: H1N1 at the Open Directory Project

- Real-time map of swine flu infections

- U.S. Government swine, avian and pandemic flu portal

- Pandemic Flu Planning Checklist for Individuals and Families

- Global map of reported H1N1 outbreaks in 2009

- H1N1 swine flu outbreak timeline

- Swine Flu Outbreak, Influenza Virus Resource — sequences and related resources (GenBank, NCBI)

- BioHealthBase Bioinformatics Resource Center Database of influenza genomic sequences and related information.

- Medical Encyclopedia Medline Plus: Swine Flu

UN World Health Organization (WHO)

- Swine influenza, at the World Health Organization

- RSS feed

- WHO's current Pandemic Influenza Phase

- @whonews twitter account

USA Centers for Disease Control (CDC)

- H1N1 Influenza (Flu) portal

- Guidance for Clinicians on Identifying and Caring for Patients with Swine-origin Influenza A (H1N1) Virus Infection

- Interim Guidance on Case Definitions for Swine Influenza A (H1N1) Human Case Investigations for state and local health department investigations, defines confirmed, probable and suspected

- Social Media Tools, inc. Swine Flu (mobile information, widgets, videos, podcasts, RSS feeds, social networking, etc.)

- H1N1 Influenza Virus - CDC Workplace (NIOSH)

- NIOSH-Approved N95 Disposable Particulate Respirators

European Centre for Disease Prevention and Control (ECDC)

- Threat Assessment for Swine Influenza

- Swine Influenza Information Home

- ECDC H1N1 Situation Report

- Swine Influenza FAQs

- Medical Advice for H1N1 from ECDC

Pan-American Health Organization (PAHO)

- Swine Influenza portal

- Influenza cases by a new sub-type: Regional Update (28 April 2009 13:00 WDC) (Epidemiological Alerts Vol. 6, No. 14)