Additional costs would come from medical treatment of 18 million to 45 million people, and total economic costs would be approximately $700 billion. In children, gastrointestinal symptoms such as, Flu symptoms that improve but then relapse with a high fever and severe cough (can be bacterial pneumonia), (In infants) far fewer wet diapers than usual. [253] The Army was deeply involved in this research due to its experience of influenza in World War I, when thousands of troops were killed by the virus in a matter of months. 'Nip it in the butt' or 'Nip it in the bud'. Most influenza virus strains are not very infectious and each infected individual will only go on to infect one or two other individuals (the basic reproduction number for influenza is generally around 1.4). [18] Influenza may also affect other animals, including pigs, horses, and birds. [23] Children are much more infectious than adults and shed virus from just before they develop symptoms until two weeks after infection. [150], Social distancing strategies used during past pandemics, such as quarantines, travel restrictions, and the closing of schools, churches and theaters, have been employed to slow the spread of influenza viruses. . [2] A number of rapid tests are available; however, people may still have the infection even if the results are negative. In addition, if a child (or presumably an adult) seems to be getting better and then relapses with a high fever, that is a danger sign since this relapse can be bacterial pneumonia. The relative importance of these three modes of transmission is unclear, and they may all contribute to the spread of the virus. One review gives an incidence of about one case per million vaccinations. actually a swine flu) or of transmission from pigs to people; instead, the virus spreads from person to person. The resulting rapid change in viral genetics produces antigenic shifts, which are sudden changes from one antigen to another. [154][155] Children and teenagers with flu symptoms (particularly fever) should avoid taking aspirin during an influenza infection (especially influenza type B), because doing so can lead to Reye's syndrome, a rare but potentially fatal disease of the liver. [23], The word Influenza comes from the Italian language meaning "influence" and refers to the cause of the disease; initially, this ascribed illness to unfavorable astrological influences. Modern medicine has found that inhaling certain … All Free. [106] Strains that are easily transmitted between people have hemagglutinin proteins that bind to receptors in the upper part of the respiratory tract, such as in the nose, throat and mouth. [1], Roughly three times per century, a pandemic occurs, which infects a large proportion of the world's population and can kill tens of millions of people (see pandemics section). [34] Two decision analysis studies[35][36] suggest that during local outbreaks of influenza, the prevalence will be over 70%. [43], The two classes of antiviral medications used against influenza are neuraminidase inhibitors (oseltamivir, zanamivir, laninamivir and peramivir) and M2 protein inhibitors (adamantane derivatives). [55] Mutations can cause small changes in the hemagglutinin and neuraminidase antigens on the surface of the virus. 10 times higher by recent estimates). influenza. [5] The most common symptoms include: high fever, runny nose, sore throat, muscle and joint pain, headache, coughing, and feeling tired. Vous le trouverez dans une ou plusieurs des lignes ci-dessous. [135] It has generally been found to be a cost-effective intervention, especially in children[136] and the elderly,[137] however the results of economic evaluations of influenza vaccination have often been found to be dependent on key assumptions. Influenza A viruses are classified into subtypes based on antibody responses to HA and NA. flu synonyms, flu pronunciation, flu translation, English dictionary definition of flu. [177] Getting infected by influenza itself increases both the risk of death (up to 1 in 10,000) and increases the risk of developing GBS to a much higher level than the highest level of suspected vaccine involvement (approx. [221] Symptoms in 1918 were so unusual that initially influenza was misdiagnosed as dengue, cholera, or typhoid. Although mortality is usually low, the virus can produce weight loss and poor growth, causing economic loss to farmers. Influenza is commonly called the flu, but it's not the same as stomach \"flu\" viruses that cause diarrhea and vomiting.For most people, influenza resolves on its own. Influenza, commonly known as "the flu", is an infectious disease caused by an influenza virus. For other uses, see, Structure, properties, and subtype nomenclature. [138][139], These are the main ways that influenza spreads, When vaccines and antiviral medications are limited, non-pharmaceutical interventions are essential to reduce transmission and spread. [254], Influenza produces direct costs due to lost productivity and associated medical treatment, as well as indirect costs of preventive measures. [85], Once inside the cell, the acidic conditions in the endosome cause two events to happen: First, part of the hemagglutinin protein fuses the viral envelope with the vacuole's membrane, then the M2 ion channel allows protons to move through the viral envelope and acidify the core of the virus, which causes the core to disassemble and release the viral RNA and core proteins. [292], In 2009, a swine-origin H1N1 virus strain commonly referred to as "swine flu" caused the 2009 flu pandemic, but there is no evidence that it is endemic to pigs (i.e. Increased travel due to the Northern Hemisphere winter holiday season may also play a role. [84] In mild and avirulent viruses, the structure of the hemagglutinin means that it can only be cleaved by proteases found in the throat and lungs, so these viruses cannot infect other tissues. [278] The symptoms following infection with low-pathogenicity avian influenza may be as mild as ruffled feathers, a small reduction in egg production, or weight loss combined with minor respiratory disease. What made you want to look up influenza? One of the mechanisms is believed to be the inhibition of adrenocorticotropic hormone (ACTH) resulting in lowered cortisol levels. influenza definition: 1. formal for flu 2. formal for flu 3. flu. [220] In comparison to vaccines, the development of anti-influenza drugs has been slower, with amantadine being licensed in 1966 and, almost thirty years later, the next class of drugs (the neuraminidase inhibitors) being developed. It was applied specifically to an influenza epidemic which began in Italy in 1743, later adopted in English … [12] No benefit has been found in those with other health problems. [107] This difference in the site of infection may be part of the reason why the H5N1 strain causes severe viral pneumonia in the lungs, but is not easily transmitted by people coughing and sneezing. influenza; an acute, commonly epidemic disease characterized by respiratory symptoms and general prostration: … People with emphysema, chronic bronchitis or asthma may experience shortness of breath while they have the flu, and influenza may cause worsening of coronary heart disease or congestive heart failure. [90] As before, the viruses adhere to the cell through hemagglutinin; the mature viruses detach once their neuraminidase has cleaved sialic acid residues from the host cell. Diarrhea is not usually a symptom of influenza in adults,[20] although it has been seen in some human cases of the H5N1 "bird flu"[33] and can be a symptom in children. [2][5], Three of the four types of influenza viruses affect humans: Type A, Type B, and Type C.[2][7] Type D has not been known to infect humans, but is believed to have the potential to do so. [250] However, it was not until Wendell Stanley first crystallized tobacco mosaic virus in 1935 that the non-cellular nature of viruses was appreciated. It is highly infectious to the susceptible, … Enrich your vocabulary with the English Definition dictionary It is not limited to humans, most mammals and many birds can also … a type of infectious illness usually causing headache, fever, a cold etc. (medicine) An acute contagious disease of the upper airways and lungs, caused by a virus, which rapidly spreads around the world in seasonal epidemics.quotations ▼ 1.1. [207][208] Although the virus seems to have caused epidemics throughout human history, historical data on influenza are difficult to interpret, because the symptoms can be similar to those of other respiratory diseases. It was incorrectly assumed that the cause of influenza was bacterial in origin from 1892 (with Haemophilus influenzae being discovered by and suggested as the origin of influenza by R. F. J. Influenza. The Italian word also has the sense ‘an outbreak of an epidemic’, hence ‘epidemic’. [256] However, the economic impacts of past pandemics have not been intensively studied, and some authors have suggested that the Spanish influenza actually had a positive long-term effect on per-capita income growth, despite a large reduction in the working population and severe short-term depressive effects. The word Influenza comes from the Italian language meaning "influence" and refers to the cause of the disease; initially, this ascribed illness to unfavorable astrological influences. Flu complications may vary and for some children, can include pneumonia and even death. [203] This huge death toll was caused by an extremely high infection rate of up to 50% and the extreme severity of the symptoms, suspected to be caused by cytokine storms. influenza translation in English - French Reverso dictionary, see also 'influential',influence',influx',inflexion', examples, definition, conjugation [1] This is believed to occur mostly over relatively short distances. [82] Influenza infection and replication is a multi-step process: First, the virus has to bind to and enter the cell, then deliver its genome to a site where it can produce new copies of viral proteins and RNA, assemble these components into new viral particles, and, last, exit the host cell. [7][8] Usually, the virus is spread through the air from coughs or sneezes. [92][93] Homologous recombination can arise during viral genome replication by the RNA polymerase switching from one template to another, a process known as copy choice. [105], The viral hemagglutinin protein is responsible for determining both which species a strain can infect and where in the human respiratory tract a strain of influenza will bind. The short generation time means that influenza epidemics generally peak at around 2 months and burn out after 3 months: the decision to intervene in an influenza epidemic, therefore, has to be taken early, and the decision is therefore often made on the back of incomplete data. [261][262], In an assessment of the 2009 H1N1 pandemic on selected countries in the Southern Hemisphere, data suggest that all countries experienced some time-limited and/or geographically isolated socioeconomic effects and a temporary decrease in tourism most likely due to fear of 2009 H1N1 disease. [72] The length of each particle varies considerably, owing to the fact that influenza is pleomorphic, and can be in excess of many tens of micrometers, producing filamentous virions. [263][needs update], Research on influenza includes studies on molecular virology, how the virus produces disease (pathogenesis), host immune responses, viral genomics, and how the virus spreads (epidemiology). Several Spanish cities saw large scale deaths, among the fatalities the Queen of Spain, Anna of Austria. [113][114] However, another possibility is that these large amounts of cytokines are just a result of the massive levels of viral replication produced by these strains, and the immune response does not itself contribute to the disease. Test Your Knowledge - and learn some interesting things along the way. [185] H5N1 exhibits seasonality in both humans and birds.[186][187]. influenza - WordReference English dictionary, questions, discussion and forums. [87] These medications are sometimes effective against influenza A if given early in the infection but are ineffective against influenza B viruses, which lack the M2 drug target. [95] In immunocompromised people, viral shedding can continue for longer than two weeks. [125] Whether immunizing health care workers affects patient outcomes is controversial with some reviews finding insufficient evidence[126][127] and others finding tentative evidence. Send us feedback. : from Italian, literally ‘influence’, from medieval Latin influentia ‘inflow’, from Latin influere, from in-‘into’ + fluere ‘to flow’. The stars aligned just so you could feel miserable. [5][9][10] A person may be infectious to others both before and during the time they are showing symptoms. [102] However, if the virus is present in mucus, this can protect it for longer periods (up to 17 days on banknotes). [166] This high level of resistance may be due to the easy availability of amantadines as part of over-the-counter cold remedies in countries such as China and Russia,[167] and their use to prevent outbreaks of influenza in farmed poultry. [39][40] The obvious symptom is trouble breathing. As many as 25 million may have been killed in the first 25 weeks; in contrast, HIV/AIDS has killed 25 million in its first 25 years. In Rome, over 8,000 people were killed. [1] In the developing world the effects are less clear; however, it appears that children are affected to a greater degree. 1. an acute, contagious, infectious disease, caused by any of various viruses and characterized by inflammation of the respiratory tract, fever, and muscular pain. [79] This is important in the emergence of pandemics, as discussed below in the section on epidemiology. [128][129], Due to the high mutation rate of the virus, a particular influenza vaccine usually confers protection for no more than a few years. [87], These core proteins and vRNA form a complex that is transported into the cell nucleus, where the RNA-dependent RNA polymerase begins transcribing complementary positive-sense vRNA (Steps 3a and b). [255] It has been estimated that a future pandemic could cause hundreds of billions of dollars in direct and indirect costs. Antigenic Characterization of Influenza Viruses “Antigens” are … These different types of HA and NA form the basis of the H and N distinctions in, for example, H5N1. Influenza is a contagious, acute respiratory illness caused by influenza viruses, usually influenza A or B subtypes. The virus also survives longer on surfaces at colder temperatures and aerosol transmission of the virus is highest in cold environments (less than 5 °C) with low relative humidity. The name influenza comes from the Italian: influenza, meaning. Strains of all subtypes of influenza A virus have been isolated from wild birds, although disease is uncommon. ", "Lesser-Known Strain of Bird Flu Kills 2 in China", "Human infection with influenza A(H7N9) virus in China", "Deadly Bird Flu Spreading in China, Unclear How", "Background and summary of human infection with influenza A(H7N9) virus – as of 5 April 2013", "Analysis of recent scientific information on avian influenza A(H7N9) virus", "Cases of swine influenza in humans: a review of the literature", "Press Release: A/H1N1 influenza like human illness in Mexico and the USA: OIE statement", "W.H.O. However, in highly virulent strains, such as H5N1, the hemagglutinin can be cleaved by a wide variety of proteases, allowing the virus to spread throughout the body. [46], The fourth family of influenza viruses – Influenza D – was identified in 2016. 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'influenza' est un terme alternatif pour 'flu'. [54] The influenza A virus can be subdivided into different serotypes based on the antibody response to these viruses. Definition of influenza written for English Language Learners from the Merriam-Webster Learner's Dictionary with audio pronunciations, usage examples, and count/noncount noun labels. "[179], These conditions can impair coughing, swallowing, clearing the airways, and in the worst cases, breathing. People at higher risk of developing flu complications include: 1. Definition of influenza. Wild aquatic birds are the natural hosts for a large variety of influenza A. [293][294] This strain is a reassortment of several strains of H1N1 that are usually found separately, in humans, birds, and pigs. [140], There are a number of rapid tests for the flu. [32] Influenza symptoms are a mixture of symptoms of common cold and pneumonia, body ache, headache, and fatigue. Hence, the majority of newly manufactured influenza viruses are mutants; this causes antigenic drift, which is a slow change in the antigens on the viral surface over time. [194] Different methods in 2010 by the Centers for Disease Control and Prevention (CDC) reported a range from a low of about 3,300 deaths to a high of 49,000 per year. Influenza is a viral infection that attacks your respiratory system — your nose, throat and lungs. [198] However, since the strains produced by drift will still be reasonably similar to the older strains, some people will still be immune to them. [279] Since these mild symptoms can make diagnosis in the field difficult, tracking the spread of avian influenza requires laboratory testing of samples from infected birds. The WHO points out that one cluster did not have two of the cases lab confirmed and further points out, as a matter of baseline information, that some viruses are able to cause limited human-to-human transmission under conditions of close contact but are not transmissible enough to cause large community outbreaks. [55] As a result of this lack of antigenic diversity, a degree of immunity to influenza B is usually acquired at an early age. [6] 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". [148] Alcohol is an effective sanitizer against influenza viruses, while quaternary ammonium compounds can be used with alcohol so that the sanitizing effect lasts for longer. [27] The length of time the virus will persist on a surface varies, with the virus surviving for one to two days on hard, non-porous surfaces such as plastic or metal, for about fifteen minutes on dry paper tissues, and only five minutes on skin. [74] For example, the influenza A genome contains 11 genes on eight pieces of RNA, encoding for 11 proteins: hemagglutinin (HA), neuraminidase (NA), nucleoprotein (NP), M1 (matrix 1 protein), M2, NS1 (non-structural protein 1), NS2 (other name is NEP, nuclear export protein), PA, PB1 (polymerase basic 1), PB1-F2 and PB2. [295], "Flu" and "Grippe" redirect here. At one point the effect of the flu was believed to be caused by the influence of the stars. [149] At home, this can be done effectively with a diluted chlorine bleach. [124] In those at high risk immunization may reduce the risk of heart disease. [80][81], Viruses can replicate only in living cells. [247] The first influenza virus to be isolated was from poultry, when in 1901, the agent causing a disease called "fowl plague" was passed through Chamberland filters, which have pores that are too small for bacteria to pass through. [1] Symptoms can be mild to severe. [37] According to the CDC, rapid diagnostic tests have a sensitivity of 50–75% and specificity of 90–95% when compared with viral culture. Nevertheless, strategies endorsed by experts for all phases of flu outbreaks include hand and respiratory hygiene, self-isolation by symptomatic individuals and the use of face masks by them and their caregivers, surface disinfection, rapid testing and diagnosis, and contact tracing. All types of influenza are commonly called "the flu.". [14] In the northern and southern parts of the world, outbreaks occur mainly in the winter, while around the equator, outbreaks may occur at any time of the year. Pandemics continued sporadically throughout the 17th and 18th centuries, with the pandemic of 1830–1833 being particularly widespread; it infected approximately a quarter of the people exposed. Not pandemic, but included for comparison purposes. Influenza, also called flu or grippe, an acute viral infection of the upper or lower respiratory tract that is marked by fever, chills, and a generalized feeling of weakness and pain in the muscles, … [146], Even healthy people can be affected, and serious problems from influenza can happen at any age. [1] A vaccine made for one year may not be useful in the following year, since the virus evolves rapidly. This could explain why influenza occurs mostly in winter and during the tropical rainy season, when people stay indoors, away from the sun, and their vitamin D levels fall. [163], Overall the benefits of neuraminidase inhibitors in those who are otherwise healthy do not appear to be greater than the risks. [6] Complications of influenza may include viral pneumonia, secondary bacterial pneumonia, sinus infections, and worsening of previous health problems such as asthma or heart failure. Also, when two or more viruses infect a cell, genetic variation may be generated by homologous recombination. Hemagglutinin and neuraminidase molecules cluster into a bulge in the cell membrane. However, influenza B mutates enough that lasting immunity is not possible. [2] A type of polymerase chain reaction that detects the virus's RNA is more accurate. In all, 50 human cases are known to have occurred since the virus was identified in the mid-20th century, which have resulted in six deaths. noun. noun. Therapeutic biologics are designed to activate the immune response to virus or antigens. During this pandemic, influenza killed about 1% of its victims. The only other animals known to be susceptible to influenza B infection are seals[61] and ferrets. The inactivated vaccine seemed to lower the risk of getting flu for the season from 30% to 11%. [153] It should be done within 3–4 days of symptom onset, as upper respiratory viral shedding takes a downward spiral after that. Recommendations for these community restrictions are usually on a case-by-case basis. Governments worldwide have spent billions of U.S. dollars preparing and planning for a potential H5N1 avian influenza pandemic, with costs associated with purchasing drugs and vaccines as well as developing disaster drills and strategies for improved border controls. Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free! This new variant then replaces the older strains as it rapidly sweeps through the human population, often causing an epidemic. In some cases, other forms of social distancing including school closures and travel restrictions are recommended. [192][193] One method of calculating influenza mortality produced an estimate of 41,400 average deaths per year in the United States between 1979 and 2001. [83] After the hemagglutinin is cleaved by a protease, the cell imports the virus by endocytosis. [2], Frequent hand washing reduces the risk of viral spread, as does wearing a surgical mask. [96], Influenza can be spread in three main ways:[97][98] by direct transmission (when an infected person sneezes mucus directly into the eyes, nose or mouth of another person); the airborne route (when someone inhales the aerosols produced by an infected person coughing, sneezing or spitting) and through hand-to-eye, hand-to-nose, or hand-to-mouth transmission, either from contaminated surfaces or from direct personal contact such as a handshake. [220], Later flu pandemics were not so devastating. Influenza models, such as murine influenza, are convenient models to test the effects of prophylactic and therapeutic biologics. 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