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H1N1
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 Spanish flu, the 1977 Russian flu pandemic and the 2009 swine flu pandemic. It is an orthomyxovirus that contains the glycoproteins hemagglutinin and neuraminidase. For this reason, they are described as H1N1, H1N2 etc., depending on the type of H or N antigens they express with metabolic synergy. 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. Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a small fraction of all seasonal influenza, for instance in 2004–2005. Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza). Its size is in di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2009 Flu Pandemic
The 2009 swine flu pandemic, caused by the H1N1 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 being the 1918–1920 Spanish flu pandemic and the second being the 1977 Russian flu). 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". Some studies estimated that the real number of cases including asymptomatic and mild cases could be 700 million to 1.4 billion people—or 11 to 21 percent of the global population of 6.8 billion at the time. The lower value of 700 million is more than the 500 million people estimated to have been infected by the Spanish flu pandemic. However, the Spanish flu infected approximat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
2009 Swine Flu Pandemic
The 2009 swine flu pandemic, caused by the H1N1 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 being the 1918–1920 Spanish flu pandemic and the second being the 1977 Russian flu). 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". Some studies estimated that the real number of cases including asymptomatic and mild cases could be 700 million to 1.4 billion people—or 11 to 21 percent of the global population of 6.8 billion at the time. The lower value of 700 million is more than the 500 million people estimated to have been infected by the Spanish flu pandemic. However, the Spanish flu infected approxi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pandemic H1N1/09 Virus
The pandemic H1N1/09 virus is a swine origin influenza A virus subtype H1N1 strain that was responsible for the 2009 swine flu pandemic. This strain is often called swine flu by the public media. For other names, see the Nomenclature section below. Viral characteristics The virus is a novel strain of the influenza virus, for which existing vaccines against seasonal flu provided no protection. A study at the U.S. Centers for Disease Control and Prevention (CDC) 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 then-new strain, while adults aged 18 to 64 had 6–9%, and older adults 34%. Much reporting of early analysis repeated 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 typi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swine Influenza
Swine influenza is an infection caused by any of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) refers to any strain of the influenza family of viruses that is endemic in pigs. As of 2009, identified SIV strains include influenza C and the subtypes of influenza A known as H1N1, H1N2, H2N1, H3N1, H3N2, and H2N3. Swine influenza virus is common throughout pig populations worldwide. Transmission of the virus from pigs to humans is rare, and does not always lead to human flu, often resulting only in the production of antibodies in the blood. If transmission causes human flu, it is called zoonotic swine flu. People with regular exposure to pigs are at increased risk of swine flu infections. Around the mid-20th century, identification of influenza subtypes was made possible, allowing accurate diagnosis of transmission to humans. Since then, only 50 such transmissions have been confirmed. These strains of swine flu rarel ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
H3N2
Influenza A virus subtype H3N2 (A/H3N2) is a subtype of viruses that causes influenza (flu). H3N2 viruses can infect birds and mammals. In birds, humans, and pigs, the virus has mutated into many strains. In years in which H3N2 is the predominant strain, there are more hospitalizations. Classification H3N2 is a subtype of the viral genus Influenzavirus A, which is an important cause of human influenza. Its name derives from the forms of the two kinds of proteins on the surface of its coat, hemagglutinin (H) and neuraminidase (N). By reassortment, H3N2 exchanges genes for internal proteins with other influenza subtypes. Seasonal H3N2 flu Seasonal influenza kills an estimated 36,000 people in the United States each year. Flu vaccines are based on predicting which "mutants" of H1N1, H3N2, H1N2, and influenza B will proliferate in the next season. Separate vaccines are developed for the Northern and Southern Hemispheres in preparation for their annual epidemics. In the tropics, i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Human Influenza
Influenza, commonly known as "the flu", is an infectious disease caused by influenza viruses. Symptoms range from mild to severe and often include fever, runny nose, sore throat, muscle pain, headache, coughing, and fatigue. These symptoms begin from one to four days after exposure to the virus (typically two days) and last for about 2–8 days. Diarrhea and vomiting can occur, particularly in children. Influenza may progress to pneumonia, which can be caused by the virus or by a subsequent bacterial infection. Other complications of infection include acute respiratory distress syndrome, meningitis, encephalitis, and worsening of pre-existing health problems such as asthma and cardiovascular disease. There are four types of influenza virus, termed influenza viruses A, B, C, and D. Aquatic birds are the primary source of Influenza A virus (IAV), which is also widespread in various mammals, including humans and pigs. Influenza B virus (IBV) and Influenza C virus (ICV) primari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1977 Russian Flu
The 1977 Russian flu was an influenza pandemic that was first reported by the Soviet Union in 1977 and lasted until 1979. The outbreak in northern China started in May 1977, slightly earlier than that in the Soviet Union. The pandemic mostly affected population younger than 25 or 26 years of age, and resulted in approximately 700,000 deaths worldwide. It was caused by an H1N1 flu strain which highly resembled a virus strain circulating worldwide from 1946 to 1957. Genetic analysis and several unusual characteristics of the 1977 Russian flu have prompted many researchers to say that the virus was released to the public through a laboratory accident, or resulted from a live-vaccine trial escape. History of outbreak In May 1977, an outbreak of flu took place in northern China including Liaoning, Jilin and Tianjin. The strain was isolated and determined by Chinese researchers to be H1N1, which mostly affected students in middle and primary schools who lacked immunity to H1N1 virus. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1918 Flu Pandemic
The 1918–1920 influenza pandemic, commonly known by the misnomer Spanish flu or as the Great Influenza epidemic, was an exceptionally deadly global influenza pandemic caused by the H1N1 influenza A virus. The earliest documented case was March 1918 in Kansas, United States, with further cases recorded in France, Germany and the United Kingdom in April. Two years later, nearly a third of the global population, or an estimated 500 million people, had been infected in four successive waves. Estimates of deaths range from 17 million to 50 million, and possibly as high as 100 million, making it one of the deadliest pandemics in history. The pandemic broke out near the end of World War I, when wartime censors suppressed bad news in the belligerent countries to maintain morale, but newspapers freely reported the outbreak in neutral Spain, creating a false impression of Spain as the epicenter and leading to the "Spanish flu" misnomer. Limited historical epidemiological ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spanish Flu
The 1918–1920 influenza pandemic, commonly known by the misnomer Spanish flu or as the Great Influenza epidemic, was an exceptionally deadly global influenza pandemic caused by the influenza A virus subtype H1N1, H1N1 influenza A virus. The earliest documented case was March 1918 in Kansas, United States, with further cases recorded in France, Germany and the United Kingdom in April. Two years later, nearly a third of the global population, or an estimated 500 million people, had been infected in four successive waves. Estimates of deaths range from 17 million to 50 million, and possibly as high as 100 million, making it List of epidemics, one of the deadliest pandemics in history. The pandemic broke out near the end of World War I, when wartime Censorship, censors suppressed bad news in the belligerent countries to maintain morale, but newspapers Freedom of the press, freely reported the outbreak in Spain during World War I, neutral Spain, creating a false impression ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Orthomyxovirus
''Orthomyxoviridae'' (from Greek ὀρθός, ''orthós'' 'straight' + μύξα, ''mýxa'' 'mucus') is a family of negative-sense RNA viruses. It includes seven genera: ''Alphainfluenzavirus'', ''Betainfluenzavirus'', '' Gammainfluenzavirus'', '' Deltainfluenzavirus'', ''Isavirus'', ''Thogotovirus'', and ''Quaranjavirus''. The first four genera contain viruses that cause influenza in birds (see also avian influenza) and mammals, including humans. Isaviruses infect salmon; the thogotoviruses are arboviruses, infecting vertebrates and invertebrates (such as ticks and mosquitoes). The Quaranjaviruses are also arboviruses, infecting vertebrates (birds) and invertebrates (arthropods). The four genera of Influenza virus that infect vertebrates, which are identified by antigenic differences in their nucleoprotein and matrix protein, are as follows: * ''Alphainfluenzavirus'' infects humans, other mammals, and birds, and causes all flu pandemics * ''Betainfluenzavirus'' infects humans a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Influenza A Virus
'' A virus'' (''IAV'') causes influenza in birds and some mammals, and is the only species of the genus ''Alphainfluenzavirus'' of the virus family ''Orthomyxoviridae''. Strains of all subtypes of influenza A virus have been isolated from wild birds, although disease is uncommon. Some isolates of influenza A virus cause severe disease both in domestic poultry and, rarely, in humans. Occasionally, viruses are transmitted from wild aquatic birds to domestic poultry, and this may cause an outbreak or give rise to human influenza pandemics. Influenza A viruses are negative-sense, single-stranded, segmented RNA viruses. The several subtypes are labeled according to an H number (for the type of hemagglutinin) and an N number (for the type of neuraminidase). There are 18 different known H antigens (H1 to H18) and 11 different known N antigens (N1 to N11). H17N10 was isolated from fruit bats in 2012. H18N11 was discovered in a Peruvian bat in 2013. Each virus subtype has mutated into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pandemic
A pandemic () is an epidemic of an infectious disease that has spread across a large region, for instance multiple continents or worldwide, affecting a substantial number of individuals. A widespread endemic disease with a stable number of infected individuals is not a pandemic. Widespread endemic diseases with a stable number of infected individuals such as recurrences of seasonal influenza are generally excluded as they occur simultaneously in large regions of the globe rather than being spread worldwide. Throughout human history, there have been a number of pandemics of diseases such as smallpox. The most fatal pandemic in recorded history was the Black Death—also known as The Plague—which killed an estimated 75–200 million people in the 14th century. The term had not been used then but was used for later epidemics, including the 1918 influenza pandemic—more commonly known as the Spanish flu. Current pandemics include HIV/AIDS and COVID-19. Definition A pand ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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