In virology, influenza A virus subtype H1N1 (A/H1N1) is a subtype of influenza A virus. Major outbreaks of H1N1 strains in humans include the 1918 Spanish flu pandemic, the 1977 Russian flu pandemic and the 2009 swine flu pandemic. It is an orthomyxovirus that contains the glycoproteins hemagglutinin (H) and neuraminidase (N), antigens whose subtypes are used to classify the strains of the virus as H1N1, H1N2 etc. Hemagglutinin causes red blood cells to clump together and binds the virus to the infected cell. Neuraminidase is a type of glycoside hydrolase enzyme which helps to move the virus particles through the infected cell and assist in budding from the host cells.
The 2009 swine flu pandemic, caused by the H1N1/swine flu/influenza virus and declared by the World Health Organization (WHO) from June 2009 to August 2010, is the third recent flu pandemic involving the H1N1 virus. The first two cases were discovered independently in the United States in April 2009. The virus appeared to be a new strain of H1N1 that resulted from a previous triple reassortment of bird, swine, and human flu viruses which further combined with a Eurasian pig flu virus, leading to the term "swine flu".
The 2009 flu pandemic in the United States was caused by a novel strain of the Influenza A/H1N1 virus, commonly referred to as "swine flu", that was first detected on 15 April 2009. While the 2009 H1N1 virus strain was commonly referred to as "swine flu", there is no evidence that it is endemic to pigs or of transmission from pigs to people; instead, the virus spreads from person to person. On April 25, the World Health Organization declared a public health emergency, followed concurringly by the Obama administration on April 26.
The 2009 swine flu pandemic in Canada was part of an epidemic in 2009 of a new strain of influenza A virus subtype H1N1 causing what has been commonly called swine flu. In Canada, roughly 10% of the populace has been infected with the virus, with 428 confirmed deaths ; non-fatal individual cases are for the most part no longer being recorded. About 40% of Canadians have been immunized against H1N1 since a national vaccination campaign began in October 2009, with Canada among the countries in the world leading in the percentage of the population that has been vaccinated. The widespread effect of H1N1 in Canada raised concerns during the months leading to the XXI Olympic Winter Games, which took place in Vancouver in February 2010.
This article covers the chronology of the 2009 novel influenza A (H1N1) pandemic. Flag icons denote the first announcements of confirmed cases by the respective nation-states, their first deaths, and relevant sessions and announcements of the World Health Organization (WHO), the European Union , and the U.S. Centers for Disease Control (CDC).
In March and April 2009, an outbreak of a new strain of influenza commonly referred to as "swine flu" infected many people in Mexico and other parts of the world, causing illness ranging from mild to severe. Initial reports suggested that the outbreak had started in February due to farming practices at a pig farm half-owned by Smithfield Foods. Smithfield Foods stated that it had found no clinical signs or symptoms of the presence of swine influenza in the company's swine herd, or among its employees at its joint ventures in Mexico, that it routinely administers influenza virus vaccination to their swine herds and that it conducts monthly testing for the presence of swine influenza. The new strain was identified as a combination of several different strains of Influenzavirus A, subtype H1N1, including separate strains of this subtype circulating in humans and in pigs. The World Health Organization (WHO) and the U.S. Centers for Disease Control and Prevention (CDC) expressed serious concerns that the new strain, which transmits between humans and has had a relatively high mortality rate in the possible and confirmed Mexican cases, has the potential to become an influenza pandemic. It was reported that, because the virus was already widespread, containment would be impossible. The WHO declared a public health emergency of international concern in response to the outbreak on April 25, 2009.
This article deals with the status and efforts regarding the 2009 swine flu pandemic by country and continent/region.
In March and April 2009, an outbreak of a new strain of flu, popularly known as swine flu was discovered to have infected several people in Mexico and the states of California and Texas in the United States. On April 28 Costa Rica became the first Central American country to report the outbreak of the virus, with a confirmed infection. As of November 4 the Costa Rican Ministry of Health had 1,596 confirmed cases, 1,275 pending cases, 8,000 already discarded, and 38 deaths.
The 2009 swine flu pandemic in Brazil began on April 25, 2009, with two people, spreading to 34 over the first two weeks. CDC calculate that Africa and Southeast Asia, which have 38% of the world's population, accounted for a disproportionate 51% of the deaths.
The influenza A virus subtype H1N1 arrived in Argentina in late April 2009, through air traffic contact with endemic areas, especially Mexico and the United States.
The 2009 flu pandemic in South America was part of a global epidemic in 2009 of a new strain of influenza A virus subtype H1N1, causing what has been commonly called swine flu. As of 9 June 2009, the virus had affected at least 2,000 people in South America, with at least 4 confirmed deaths. On 3 May 2009, the first case of the flu in South America was confirmed in a Colombian man who recently travelled from Mexico – since then, it has spread throughout the continent. By far, the most affected country has been Chile, with more than 12,000 confirmed cases, 104 deaths, and the highest per capita incidence in the world.
The 2009 flu pandemic in Asia, part of an epidemic in 2009 of a new strain of influenza A virus subtype H1N1 causing what has been commonly called swine flu, afflicted at least 394,133 people in Asia with 2,137 confirmed deaths: there were 1,035 deaths confirmed in India, 737 deaths in China, 415 deaths in Turkey, 192 deaths in Thailand, and 170 deaths in South Korea. Among the Asian countries, South Korea had the most confirmed cases, followed by China, Hong Kong, and Thailand.
The 2009 swine flu pandemic in North America, part of a pandemic in 2009 of a new strain of influenza A virus subtype H1N1 causing what has been commonly called swine flu, began in the United States or Mexico.
The 2009 flu pandemic in Europe was part of a pandemic involving a new strain of influenza, subtype H1N1. H1N1 is commonly called swine flu. The pandemic infected at least 125,550 people in Europe. There were 458 confirmed deaths in Turkey, 438 confirmed deaths in Russia, and 457 confirmed deaths in the United Kingdom.
The 2009 flu pandemic hit Africa two months later than other continents with the first case reported in Egypt on June 2, 2009. As of December 1, 30 countries in Africa had reported cases and 7 countries in Africa had reported a total of 108 deaths. It was the least affected continent.
The Influenza A (H1N1), also known by the name of swine flu, arrived to Uruguay on May 27, 2009.
The Influenza A (H1N1), also known as the swine flu, was detected in Venezuela on 28 May. The first infected person was a 22-year-old man in San Antonio de Los Altos, Miranda State. He was participating on a meeting in Panamá, and returned to Venezuela carrying the virus
The United States experienced the beginnings of a pandemic of a novel strain of the influenza A/H1N1 virus, commonly referred to as "swine flu", in the spring of 2009. The earliest reported cases in the US began appearing in late March 2009 in California, then spreading to infect people in Texas, New York, and other states by mid-April. Early cases were associated with recent travel to Mexico; many were students who had traveled to Mexico for Spring Break. This spread continued across the country's population and by the end of May there were approximately 0 confirmed cases throughout all 50 states.
The 2009 flu pandemic, an influenza outbreak commonly known as "swine flu", affected Portugal from May 2009 to early 2010. The outbreak caused 122 deaths in the country.
