Asian flu may refer to:
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A pandemic is an epidemic of disease that has spread across a large region, for instance multiple continents, or worldwide. A widespread endemic disease with a stable number of infected people is not a pandemic. Widespread endemic diseases with a stable number of infected people such as recurrences of seasonal flu are generally excluded as they occur simultaneously in large regions of the globe rather than being spread worldwide.
The Spanish flu, also known as the 1918 flu pandemic or La Pesadilla, was an unusually deadly influenza pandemic. Lasting from January 1918 to December 1920, it infected 500 million people – about a quarter of the world's population at the time. The death toll is estimated to have been anywhere from 17 million to 50 million, and possibly as high as 100 million, making it one of the deadliest pandemics in human history, behind the Black Death.
Influenza A virus 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.
Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds. The type with the greatest risk is highly pathogenic avian influenza (HPAI). Bird flu is similar to swine flu, dog flu, horse flu and human flu as an illness caused by strains of influenza viruses that have adapted to a specific host. Out of the three types of influenza viruses, influenza A virus is a zoonotic infection with a natural reservoir almost entirely in birds. Avian influenza, for most purposes, refers to the influenza A virus.
Antigenic shift is the process by which two or more different strains of a virus, or strain of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains. The term is often applied specifically to influenza, as that is the best-known example, but the process is also known to occur with other viruses, such as visna virus in sheep. Antigenic shift is a specific case of reassortment or viral shift that confers a phenotypic change.
Orthomyxoviridae is a family of RNA viruses. It includes seven genera: Influenzavirus A, Influenzavirus B, Influenzavirus C, Influenzavirus D, Isavirus, Thogotovirus, and Quaranjavirus. The first four genera contain viruses that cause influenza in vertebrates, including birds, humans, and other mammals. Isaviruses infect salmon; the thogotoviruses are arboviruses, infecting vertebrates and invertebrates, such as ticks and mosquitoes.
Influenza A virus subtype H5N1 (A/H5N1) is a subtype of the influenza A virus which can cause illness in humans and many other animal species. A bird-adapted strain of H5N1, called HPAI A(H5N1) for highly pathogenic avian influenza virus of type A of subtype H5N1, is the highly pathogenic causative agent of H5N1 flu, commonly known as avian influenza. It is enzootic in many bird populations, especially in Southeast Asia. One strain of HPAI A(H5N1) is spreading globally after first appearing in Asia. It is epizootic and panzootic, killing tens of millions of birds and spurring the culling of hundreds of millions of others to stem its spread. Many references to "bird flu" and H5N1 in the popular media refer to this strain.
The Hong Kong flu was a flu pandemic whose outbreak in 1968 and 1969 killed an estimated one million people all over the world. It was caused by an H3N2 strain of the influenza A virus, descended from H2N2 through antigenic shift, a genetic process in which genes from multiple subtypes reassorted to form a new virus.
Swine influenza is an infection caused by any one of several types of swine influenza viruses. Swine influenza virus (SIV) or swine-origin influenza virus (S-OIV) is any strain of the influenza family of viruses that is endemic in pigs. 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.
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 outbreak known as the Spanish flu.
An influenza pandemic is an epidemic of an influenza virus that spreads on a worldwide scale and infects a large proportion of the world population. In contrast to the regular seasonal epidemics of influenza, these pandemics occur irregularly – there have been five influenza pandemics during the last 140 years. Pandemics can cause high levels of mortality, with the 1918 Spanish flu pandemic being the worst in recorded history; this pandemic was estimated to be responsible for the deaths of 50–100 million people. The most recent, the 2009 flu pandemic, resulted in under a million deaths and is considered relatively mild.
Influenza A virus subtype H2N2 (A/H2N2) is a subtype of Influenza A virus. H2N2 has mutated into various strains including the Asian flu strain, H3N2, and various strains found in birds. It is also suspected of causing a human pandemic in 1889. The geographic spreading of the 1889 Russian flu have been studied and published.
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.
Transmission and infection of H5N1 from infected avian sources to humans has been a concern since the first documented case of human infection in 1997, due to the global spread of H5N1 that constitutes a pandemic threat.
H5N1 genetic structure is the molecular structure of the H5N1 virus's RNA.
Human mortality from H5N1 or the human fatality ratio from H5N1 or the case-fatality rate of H5N1 refer to the ratio of the number of confirmed human deaths resulting from confirmed cases of transmission and infection of H5N1 to the number of those confirmed cases. For example, if there are 100 confirmed cases of humans infected with H5N1 and 10 die, then there is a 10% human fatality ratio. H5N1 flu is a concern due to the global spread of H5N1 that constitutes a pandemic threat. The majority of H5N1 flu cases have been reported in southeast and east Asia. The case-fatality rate is central to pandemic planning. Estimates of case-fatality (CF) rates for past influenza pandemics have ranged from about 0.1% to 2-3%. As of 2008, the official World Health Organization estimate for the case-fatality rate for the outbreak of H5N1 avian influenza was approximately 60%. Public health officials in Ontario, Canada argue that the true case-fatality rate could be lower, pointing to studies suggesting it could be 4–33%, but warned that it was unlikely to be as low as the 0.1–0.4% rate that was built into many pandemic plans.
Influenza, commonly known as "the flu", is an infectious disease caused by an influenza virus. Symptoms can be mild to severe. The most common symptoms include: high fever, runny nose, sore throat, muscle and joint pain, headache, coughing, and feeling tired. These symptoms typically begin two days after exposure to the virus and most last less than a week. The cough, however, may last for more than two weeks. In children, there may be diarrhea and vomiting, but these are not common in adults. Diarrhea and vomiting occur more commonly in gastroenteritis, which is an unrelated disease and sometimes inaccurately referred to as "stomach flu" or the "24-hour flu". Complications of influenza may include viral pneumonia, secondary bacterial pneumonia, sinus infections, and worsening of previous health problems such as asthma or heart failure.
The 2009 swine flu pandemic or swine flu was an influenza pandemic that lasted from January 2009 to August 2010, and the second of the two pandemics involving H1N1 influenza virus, albeit a new strain. First described in April 2009, the virus appeared to be a new strain of H1N1, which resulted from a previous triple reassortment of bird, swine, and human flu viruses further combined with a Eurasian pig flu virus, leading to the term "swine flu". Some studies estimated that 11 to 21 percent of the global population at the time—or around 700 million to 1.4 billion people —contracted the illness. This was more than the number of people infected by the Spanish flu pandemic, but only resulted in about 150,000 to 575,000 fatalities for the 2009 pandemic. A follow-up study done in September 2010 showed that the risk of serious illness resulting from the 2009 H1N1 flu was no higher than that of the yearly seasonal flu. For comparison, the WHO estimates that 250,000 to 500,000 people die of seasonal flu annually.
The Pandemic H1N1/09 virus is a swine origin Influenza A virus subtype H1N1 virus strain that was responsible for the 2009 flu pandemic. This strain is often called swine flu by the public media. For other names, see the Nomenclature section below.
The 1957–58 influenza pandemic, also known as Asian flu, was a global pandemic of influenza A virus subtype H2N2 which originated in Guizhou, China and killed at least 1 million people worldwide.