The 1918 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.
- February 1918 – April 1920
- 25–50 million (generally accepted), other estimates range from 17 to 100 million
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.
- Variants and Subtypes
- Annual Flu
- Structure and Genetics
- Multiplicity Reactivation
- Human Influenza Virus
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- External Links
Influenza type A viruses are RNA viruses categorized into subtypes based on the type of two proteinson the surface of the viral envelope: 1. H = hemagglutinin, a protein that causes red blood cells to agglutinate. 2. N = neuraminidase, an enzyme that cleaves the glycosidic bonds of the monosaccharide sialic acid (previously called neuraminic acid)....
The annual flu (also called "seasonal flu" or "human flu") in the US "results in approximately 36,000 deaths and more than 200,000 hospitalizations each year. In addition to this human toll, influenza is annually responsible for a total cost of over $10 billion in the U.S."Globally the toll of influenza virus is estimated at 290,000–645,000 deaths ...
Influenza type A viruses are very similar in structure to influenza viruses types B, C, and D. The virus particle (also called the virion) is 80–120 nanometers in diameter such that the smallest virions adopt an elliptical shape. The length of each particle varies considerably, owing to the fact that influenza is pleomorphic, and can be in excess o...
Influenza virus is able to undergo multiplicity reactivation after inactivation by UV radiation, or by ionizing radiation.If any of the eight RNA strands that make up the genome contains damage that prevents replication or expression of an essential gene, the virus is not viable when it alone infects a cell (a single infection). However, when two o...
"Human influenza virus" usually refers to those subtypes that spread widely among humans. H1N1, H1N2, and H3N2 are the only known influenza A virus subtypes currently circulating among humans. Genetic factors in distinguishing between "human flu viruses" and "avian influenza viruses" include: 1. PB2: (RNA polymerase): Amino acid (or residue) positi...Health-EU portal European Unionresponse to influenza
- Influenza C Virus
- Structure and Variation
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Influenza viruses are members of the family Orthomyxoviridae. Influenza viruses A, B, C, and D represent the four antigenic types of influenza viruses. Of the four antigenic types, influenza A virus is the most severe, influenza B virusis less severe but can still cause outbreaks, and influenza C virus is usually only associated with minor symptoms...
Influenza viruses, like all viruses in the family Orthomyxoviridae, are enveloped RNA viruses with single stranded genomes. The antigens, matrix protein (M1) and nucleoprotein (NP), are used to determine if an influenza virus is type A, B, C, or D. The M1 protein is required for virus assembly and NP functions in transcription and replication. Thes...
Influenza virus C is different from Types A and B in its growth requirements. Because of this, it is not isolated and identified as frequently. Diagnosis is by virus isolation, serology, and other tests. Hemagglutination inhibition (HI) is one method of serology that detects antibodies for diagnostic purposes. Western blot (immunoblot assay) and en...
Because influenza virus A has an animal reservoir that contains all the known subtypes and can undergo antigenic shift, this type of influenza virus is capable of producing pandemics. Influenza viruses A and B also cause seasonal epidemics almost every year due to their ability to antigenic drift. Influenza virus C does not have this capability and...
Influenza vaccines, also known as flu shots, are vaccines that protect against infection by influenza viruses.  New versions of the vaccines are developed twice a year, as the influenza virus rapidly changes.  While their effectiveness varies from year to year, most provide modest to high protection against influenza.
An influenza pandemic is an epidemic of an influenza virus that spreads across a large region (either multiple continents or worldwide) and infects a large proportion of the population. There have been six major influenza epidemics in the last 140 years, with the 1918 flu pandemic being the most severe; this is estimated to have been responsible for the deaths of 50–100 million people.
Haemophilus influenzae (formerly called Pfeiffer's bacillus or Bacillus influenzae) is a Gram-negative, non-motile, coccobacillary, facultatively anaerobic, capnophilic pathogenic bacterium of the family Pasteurellaceae. The bacteria are mesophilic and grow best at temperatures between 35 and 37℃. H. influenzae was first described in 1892 ...