The most pupular picture :D since the panic at the web.
from ENEAS.
http://socialistworker.org/2009/04/27/capitalism-and-the-flu
| Influenza Classification and external resources | |
 | |
|---|---|
| TEM of negatively stained influenza virons, magnified approximately 100,000 times | |
| ICD-10 | J10., J11. |
| ICD-9 | 487 |
| DiseasesDB | 6791 |
| MedlinePlus | 000080 |
| eMedicine | med/1170 ped/3006 |
| MeSH | D007251 |
Influenza, commonly known as the flu, is an infectious disease caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses), that affects birds and mammals. The name influenza comes from the Italian: influenza, meaning "influence" (Latin: influentia). In humans, common symptoms of the disease are chills, fever, pharyngitis, muscle pains, severe headache, coughing, weakness and general discomfort. Coughs and fever are the most common symptoms. In more serious cases, influenza causes pneumonia, which can be fatal, particularly for the young and the elderly. Although it is often confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus. Influenza can occasionally produce nausea and vomiting, particularly in children, but these symptoms are more common in the unrelated disease gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu".
Typically, influenza is transmitted from infected mammals through the air by coughs or sneezes, creating aerosols containing the virus, and from infected birds through their droppings. Influenza can also be transmitted by saliva, nasal secretions, feces and blood. Infections also occur through contact with these body fluids or with contaminated surfaces. Flu viruses can remain infectious for about one week at human body temperature, over 30 days at 0 °C (32 °F), and for much longer periods at very low temperatures. Influenza viruses can be inactivated by disinfectants and detergents. As the virus can be inactivated by soap, frequent hand washing reduces the risk of infection.
The word Influenza comes from the Italian language and refers to the cause of the disease; initially, this ascribed illness to unfavorable astrological influences. Changes in medical thought led to its modification to influenza del freddo, meaning "influence of the cold". The word influenza was first used in English in 1743 when it was adopted, with an anglicized pronunciation, during an outbreak of the disease in Europe. Archaic terms for influenza include epidemic catarrh, grippe (from the French), sweating sickness, and Spanish fever (particularly for the 1918 pandemic strain).
The symptoms of human influenza were clearly described by Hippocrates roughly 2,400 years ago. Since then, the virus has caused numerous pandemics. Historical data on influenza are difficult to interpret, because the symptoms can be similar to those of other diseases, such as diphtheria, pneumonic plague, typhoid fever, dengue, or typhus. The first convincing record of an influenza pandemic was of an outbreak in 1580, which began in Russia and spread to Europe via Africa. In Rome, over 8,000 people were killed, and several Spanish cities were almost wiped out. 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.
The most famous and lethal outbreak was the so-called Spanish flu pandemic (type A influenza, H1N1 subtype), which lasted from 1918 to 1919. It is not known exactly how many it killed, but estimates range from 20 to 100 million people. This pandemic has been described as "the greatest medical holocaust in history" and may have killed as many people as the Black Death. 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. Indeed, symptoms in 1918 were so unusual that initially influenza was misdiagnosed as dengue, cholera, or typhoid. One observer wrote, "One of the most striking of the complications was hemorrhage from mucous membranes, especially from the nose, stomach, and intestine. Bleeding from the ears and petechial hemorrhages in the skin also occurred." The majority of deaths were from bacterial pneumonia, a secondary infection caused by influenza, but the virus also killed people directly, causing massive hemorrhages and edema in the lung.
The Spanish flu pandemic was truly global, spreading even to the Arctic and remote Pacific islands. The unusually severe disease killed between 2 and 20% of those infected, as opposed to the more usual flu epidemic mortality rate of 0.1%. Another unusual feature of this pandemic was that it mostly killed young adults, with 99% of pandemic influenza deaths occurring in people under 65, and more than half in young adults 20 to 40 years old. This is unusual since influenza is normally most deadly to the very young (under age 2) and the very old (over age 70). The total mortality of the 1918–1919 pandemic is not known, but it is estimated that 2.5% to 5% of the world's population was killed. 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.
Later flu pandemics were not so devastating. They included the 1957 Asian Flu (type A, H2N2 strain) and the 1968 Hong Kong Flu (type A, H3N2 strain), but even these smaller outbreaks killed millions of people. In later pandemics antibiotics were available to control secondary infections and this may have helped reduce mortality compared to the Spanish Flu of 1918.
The etiological cause of influenza, the Orthomyxoviridae family of viruses, was first discovered in pigs by Richard Shope in 1931. This discovery was shortly followed by the isolation of the virus from humans by a group headed by Patrick Laidlaw at the Medical Research Council of the United Kingdom in 1933.However, it was not until Wendell Stanley first crystallized tobacco mosaic virus in 1935 that the non-cellular nature of viruses was appreciated.
The first significant step towards preventing influenza was the development in 1944 of a killed-virus vaccine for influenza by Thomas Francis, Jr.. This built on work by Australian Frank Macfarlane Burnet, who showed that the virus lost virulence when it was cultured in fertilized hen's eggs. Application of this observation by Francis allowed his group of researchers at the University of Michigan to develop the first influenza vaccine, with support from the U.S. Army. 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.
Although there were scares in the State of New Jersey in 1976 (with the Swine Flu), worldwide in 1977 (with the Russian Flu), and in Hong Kong and other Asian countries in 1997 (with H5N1 avian influenza), there have been no major pandemics since the 1968 Hong Kong Flu. Immunity to previous pandemic influenza strains and vaccination may have limited the spread of the virus and may have helped prevent further pandemics.
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