Swine influenza was first proposed to be a disease related to human flu during the 1918 flu pandemic, when pigs became ill at the same time as humans. Influenza virology and animal transmission studies antigenic and genetic characteristics of swineorigin 2009 ah1n1 influenza viruses circulating in humans pdf icon 327 mb, 7 pages external icon. The spanish flu pandemic of 1918, the deadliest in history, infected an estimated 500 million people worldwideabout onethird of the planets populationand killed an estimated 20 million. The antigenetic characteristics of these viruses distinguish them from others circulating at a global level in pigs. Although there is not universal consensus regarding where the virus originated, it spread worldwide during 19181919. Humanorigin h1n1 and h3n2 strains have been identified in swine. Historical perspective emergence of influenza a h1n1. Despite the persistence of disease and pandemics throughout history, theres one consistent trend over time a gradual reduction in the death rate.
Swine influenza is an acute respiratory disease caused by influenza a viruses that circulate among pigs. Although swine flu doesnt typically affect humans, there was a global outbreak in 2009 to 2010the first flu pandemic in more than 40 years. Swine influenza is a highly contagious viral disease of the respiratory tract in swine and is distributed globally. Swine influenza fact sheet university of louisville. The 2009 flu pandemic or swine flu was an influenza pandemic that lasted from early 2009 to late 2010, and the second of the two pandemics involving h1n1 influenza virus the first of them being the 19181920 spanish flu pandemic, albeit in a new version. Influenza a virus in swine iavs can affect 70% of growing pigs each year and may lead to major economic consequences 1,2 welcome to the iavs resource site, sponsored by boehringer ingelheim. From the known history of swine influenza and the similarity of its etiologic virus to that obtained from man it seems likely that the virus of swine influenza is the surviving prototype of the. For other names, see the nomenclature section below. The centers for disease control and prevention cdc reports the earliest onset of h1n1 in the u. The latter virus, which caused a minor buried epidemic and was shown to be serially transmissible in humans, was the putative virus of 1918. The morbidity rate is usually high, and the case fatality rate low, but more severe outbreaks may be seen, and reduced growth rates in young pigs can cause economic losses. The diagram shows the full genetic history of the swineorigin influenza a h1n1 virus soiv. Swine influenza is a highly contagious viral infection of pigs. The influenza of 1918 oxford academic oxford university press.
However, occurrence of an outbreak of influenzalike clinical features in pigs at a time of widespread pandemic and epizootic influenza, reported by a notable and careful observer such as eade a prominent consulting physician at the norfolk and norwich hospital, and an expert in. The disease in swine occurs within a herd either as an epizootic or enzootic form. Origins of the 2009 h1n1 influenza pandemic in swine. The 2009 h1n1 influenza virus referred to as swine flu early on was first detected in people in the united states in april 2009. The first identification of an influenza virus as a cause of disease in pigs occurred about ten years later, in 1930. People do not normally get swine flu, but human infections can and do happen. This virus normally causes respiratory disease in pigs. Stockpiling ventilators for influenza pandemics volume 23. The diagram shows the full genetic history of the swine origin influenza a h1n1 virus soiv. Cidrap news swine influenza viruses have never been documented as the cause of a human influenza pandemic, but in 1976 they generated pandemic fears strong enough to trigger a nationwide vaccination campaign.
Swine influenza has been induced in pigs by the intranasal instillation of material from spontaneous cases of the disease as occurring epizootically in eastern iowa. Swine influenza is an infection caused by any one of several types of swine influenza viruses. In 2009, a new h1n1 influenza virus emerged, causing the first global flu pandemic in 40 years. Since 1700, there have been approximately a dozen influenza a virus pandemics. It was caused by a thennew flu virus known as h1n1, an influenza virus thats a combination of swine, avian bird, and. The committee considered available data on confirmed outbreaks of ah1n1 swine influenza in the united states of america, mexico, and canada. This virus was originally referred to as swine flu because laboratory testing showed that its gene segments were similar to influenza viruses that were most recently identified in and known to circulate among pigs. Here you will find information about the disease, how it spreads, how it can harm performance, and what measures are needed to control it. History and epidemiology of swine influenza in europe. The experimental disease has the same features as the epizootic.
It has been maintained for study by serial passages accomplished either by intranasal instillation or by pen contact. Given the history of reassortment events of swine influenza, it is likely that. Swine influenza is an acute, highly contagious, respiratory disease that results from infection with type a influenza virus. Swine influenza swine flu is a respiratory disease of pigs caused by type a influenza virus that regularly causes outbreaks of influenza in pigs.
Assist in the early severity assessment of the disease case definitions for infections with swine influenza ah1n1 virus. However, the disease has also spread from one person to another. Field isolates of variable virulence exist, and clinical manifestation may be determined by secondary organisms. Influenza diagnosis clinical and epidemiological characteristics increase of febrile respiratory illness lab isolation of influenza virus from clinical specimen e. In 1918, the cause of human influenza and its links to avian and swine influenza were unknown. Diligent preparation and effective countermeasures are critical to mitigating future influenza pandemics.
Swine flu viruses cause high levels of illness and low death rates in pigs. Transmission of swine influenza viruses to humans is uncommon. They find that the 1918 human virus then moved into pigs, creating a swine flu epidemic. Below is a timeline of major events that took place during the 2009 h1n1 pandemic.
The first discovered case involved a soldier at fort dix who. Many of the death toll numbers listed above are best estimates based on available research. The human influenza due to a novel subtype h1n1 food and. This type of influenza virus can also infect humans and birds. Swine influenza virus is a virus that is common in pigs. Swine influenza swine flu is a respiratory disease of pigs caused by type a influenza viruses that causes regular outbreaks in pigs. Swine influenza viruses belong to the species influenza a virus, genus. Few young people had any existing immunity as detected by antibody response to the h1n1 pdm09 virus, but nearly onethird of people over 60 years old had antibodies against this virus. However, sporadic human infections with swine flu have occurred.
First human infection with new influenza a h1n1 virus detected in california. A new flu virus emerges the h1n1 pdm09 virus was very different from h1n1 viruses that were circulating at the time of the pandemic. Swine flu is the name for the influenza type a virus that affects pigs swine. Pdf influenza has been recognized as a respiratory disease in swine since its first appearance concurrent with the 1918 spanish flu human. This was the cocirculation in crowded recruit barracks of 2 influenza a viruses of different subtypes.
Jun 27, 2016 the 2009 swine h1n1 flu pandemic responsible for more than 17,000 deaths worldwide originated in pigs from a very small region in central mexico, a research team is reporting. The h1n1 swine flu viruses are very different from human h1n1 viruses and, therefore. This strain is often called swine flu by the public media. H1n1 influenza or swine flu is a highly contagious acute respiratory disease of pigs caused by type a influenza virus that regularly causes outbreaks of influenza in pigs. Swine influenza swine flu is a respiratory disease of pigs caused by type a influenza viruses. In europe, swine influenza is considered one of the most important primary pathogens of swine respiratory disease and infection is primarily with h1n1, h1n2 and h3n2 influenza a viruses. The centers for disease control and prevention cdc reports the.
Swine influenza fact sheet symptoms of swine influenza the symptoms of swine flu in people are expected to be similar to the symptoms of regular human seasonal influenza and include fever, lethargy, lack of appetite and coughing. The united states has nearly half of the worlds swine influenza cases. Swine flu is a highly contagious respiratory disease in pigs caused by one of several swine influenza a viruses see the image below. Despite clinical and epidemiologic similarities to influenza pandemics of 1889, 1847, and even earlier, many questioned. The reporting of swine flu cases in two california children this week stirred memories of the 1976 episode, which caused major embarrassment for public health. The information presented in this report and information provided in two prominent publications on the 1918 influenza pandemic are then used to.
The antigenetic characteristics of these viruses distinguish them from others circulating at. Accessed 5 pdf swine flu, also called hog or pig flu, is an infection caused by any one of the several types of swine influenza virus siv which is common. Swine influenza world organization for animal health oie manual of diagnostic tests and vaccines for terrestrial animals, 2019. H1n1, h3n2 and h1n2 are the most common influenza subtypes in swine, of which avianlike h1n1 is most frequent. Swine influenza viruses may circulate among swine throughout the year, but most outbreaks occur. Swine influenza was first proposed to be a disease related to human influenza. Firstly, the outbreak of infection, arising in a specific geographical area, spreads throughout the world. Is the h1n1 swine flu virus the same as human h1n1 viruses. In virology, the pandemic h1n109 virus is a swine origin influenza a virus subtype h1n1 strain that was responsible for the 2009 swine flu pandemic. In virology, influenza a virus subtype h1n1 a h1n1 is the subtype of influenza a virus that was the most common cause of human influenza flu in 2009, and is associated with the 1918 flu pandemic it is an orthomyxovirus that contains the glycoproteins haemagglutinin and neuraminidase. Reports antigenic and genetic characteristics of swineorigin. The centers for disease control and prevention cdc identified the first two a09h1n1 swine flu cases in california on april 17, 2009, via the border infectious disease program, for a san diego county child, and a naval research facility studying a special diagnostic test, where influenza sample from the child from imperial county was tested. Two conditions must be satisfied for an outbreak of influenza to be classed as a pandemic.
The central role which swine have played in the ecology of influenza is set out in this book in 15 chapters within a comprehensive international framework. A history of influenza potter 2001 journal of applied. A 1976 outbreak of swine influenza in fort dix, new jersey, involved more than 200 cases, some of them severe, and one death. Influenza a viruses are constantly changing, making it possible on very rare occasions for nonhuman influenza viruses to change in such a way that they can infect people easily and spread efficiently from person to person. Swine influenza virus siv or swine origin influenza virus soiv is any strain of the influenza family of viruses that is endemic in pigs. In the epizootic form, the virus quickly moves through all phases of a swine. Detect and confirm cases of swine influenza ah1n1 virus infection 2. However, the zoonotic origins of the 2009 ah1n1 influenza pandemic virus pdmh1n1 remain unclear, due. The 1918 influenza pandemic was the most severe pandemic in recent history. What is the history of h1n1 influenza swine flu pandemics. Pigs are the principal hosts of classic swine influenza virus. Swine influenza virus is sometimes called siv or swine flu.
For this reason, they are described as h1n1, h1n2 etc. The reporting of swine flu cases in two california children this week stirred memories of the 1976 episode, which caused major embarrassment for public health authorities when the. Swine influenza simple english wikipedia, the free encyclopedia. There is also a survey of economic research on the subject. The result is a one health perspective on the role of swine influenza viruses sivs at the animalhumanenvironmental interface. Disease categories the links in this section will take you to a list of other diseases for that same category e. A further human case of swine influenza, athailand271 2005, contains genes from both north american and eurasian swine influenza lineages 29, indicating previous reassortment between these two swine virus lineages. In the united states, it was first identified in military personnel in spring 1918. Swine influenza aetiology epidemiology diagnosis prevention and control references swine influenza is a highly contagious viral infection of pigs. Apr 09, 2019 swine flu is a highly contagious respiratory disease in pigs caused by one of several swine influenza a viruses see the image below. Swine influenza is an acute respiratory disease caused by influenza a viruses that. Some, such as the plague of justinian and swine flu, are subject to debate based on new evidence. Asia is considered an important source of influenza a virus iav pandemics, owing to large, diverse viral reservoirs in poultry and swine. Swine influenza swine flu fact sheet what is swine flu.
Swine origin influenza a h1n1 pandemic revisited ncbi. Swine flu swine influenza is a respiratory disease caused by type a influenza. Read about swine flu history, including the dreaded 1918 flu the health workers hope is not repeated. That question did not begin to be resolved until the 1930s, when closely related influenza viruses now known to be. The 1918 influenza pandemic, the most severe in recent history, resulted in. Establish the extent of international spread of swine influenza ah1n1 virus infection 3. Swine flu is a disease caused by the influenza virus swine influenza a h1n1. Crossreactive antibody responses to the 2009 pandemic h1n1 influenza virus external icon. It was caused by an h1n1 virus with genes of avian origin. From the history of influenza epidemics and pandemics, which can be traced back with some accuracy for the past three hundred years, and with less. The committee also considered reports of possible spread to additional countries.
As of 2009, the known siv strains include influenza c and the subtypes of influenza a known as h1n1, h1n2, h2n1, h3n1, h3n2, and h2n3. First described in april 2009, the virus appeared to be a new strain of h1n1 which. Most commonly, human cases of swine flu happen in people who are around pigs but its possible for swine flu viruses to. Evolution of the 2009 h1n1 influenza virus pandemic maryland, the nation and the world. Some people with swine flu also have reported runny nose, sore throat, nausea, vomiting and diarrhea. On the advice of the committee, the who directorgeneral decided on the following. Whether eades swine outbreak was actually influenza, or some other disease, cannot be known with certainty. This disease is transmitted between the persons through coughing or sneezing with the. Interim who guidance for the surveillance of human infection.
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