Influenza complications usually arise from bacterial infections of the lower respiratory tract. Signs of a secondary respiratory infection often appear just as the victim seems to be recovering. These signs include high fever, intense chills, chest pains associated with breathing, and a productive cough with thick yellowish green sputum. If these symptoms appear, medical treatment is necessary. Other secondary infections, such as sinus or ear infections, may also require medical intervention. Heart and lung problems, and other chronic diseases, can be aggravated by influenza, which is a particular concern with elderly patients.
With children and teenagers, it is advisable to be alert for symptoms of Reye's syndrome, a rare but serious complication. Symptoms of Reye's syndrome are nausea and vomiting, and more seriously, such neurological problems as confusion or delirium. The syndrome has been associated with the use of aspirin to relieve flu symptoms.
Tuesday, July 21, 2009
Defination by jayanthi
Influenza A(H1N1) virus is a subtype of influenzavirus A and the most common cause of influenza (flu) in humans. Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a large fraction of all seasonal influenza. H1N1 strains caused roughly half of all human flu infections in 2006.[1] Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).
In June 2009, WHO declared that flu due to a new strain of swine-origin H1N1 was responsible for the 2009 flu pandemic. This strain is commonly called "swine flu" by the public media.
In June 2009, WHO declared that flu due to a new strain of swine-origin H1N1 was responsible for the 2009 flu pandemic. This strain is commonly called "swine flu" by the public media.
Monday, July 20, 2009
primila
Influenza
.
Influenza
Classification and external resources
TEM of negatively stained influenza virions, magnified approximately 100,000 times
Influenza, commonly referred to 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). The most common symptoms of the disease are chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort.[1] Fever and coughs are the most frequent 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 other influenza-like illnesses, especially the common cold, influenza is a much more severe disease than the common cold and is caused by a different type of virus.[2] Influenza may produce nausea and vomiting, particularly in children,[1] but these symptoms are more common in the unrelated gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu".[3]
Typically, influenza is transmitted through the air by coughs or sneezes, creating aerosols containing the virus. Influenza can also be transmitted by bird droppings, saliva, nasal secretions, feces and blood. Infection can also occur through contact with these body fluids or through contact with contaminated surfaces. Airborne aerosols have been thought to cause most infections, although which means of transmission is most important is not absolutely clear. Influenza viruses can be inactivated by sunlight, disinfectants and detergents.[4][5] As the virus can be inactivated by soap, frequent hand washing reduces the risk of infection.
Influenza spreads around the world in seasonal epidemics, resulting in the deaths of hundreds of thousands annually — millions in pandemic years. Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans. Often, these new strains appear when an existing flu virus spreads to humans from other animal species, or when an existing human strain picks up new genes from a virus that usually infects birds or pigs. An avian strain named H5N1 raised the concern of a new influenza pandemic, after it emerged in Asia in the 1990s, but it has not evolved to a form that spreads easily between people.[6] In April 2009 a novel flu strain evolved that combined genes from human, pig, and bird flu, initially dubbed "swine flu", emerged in Mexico, the United States, and several other nations. WHO officially declared the outbreak to be a "pandemic" on June 11, 2009.Vaccinations against influenza are usually given to people in developed countries [7] and to farmed poultry.[8] The most common human vaccine is the trivalent influenza vaccine (TIV) that contains purified and inactivated material from three viral strains. Typically, this vaccine includes material from two influenza A virus subtypes and one influenza B virus strain.[9] The TIV carries no risk of transmitting the disease, and it has very low reactivity. A vaccine formulated for one year may be ineffective in the following year, since the influenza virus evolves rapidly, and new strains quickly replace the older ones. Antiviral drugs can be used to treat influenza, with neuraminidase inhibitors being particularly effective.
.
Influenza
Classification and external resources
TEM of negatively stained influenza virions, magnified approximately 100,000 times
Influenza, commonly referred to 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). The most common symptoms of the disease are chills, fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort.[1] Fever and coughs are the most frequent 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 other influenza-like illnesses, especially the common cold, influenza is a much more severe disease than the common cold and is caused by a different type of virus.[2] Influenza may produce nausea and vomiting, particularly in children,[1] but these symptoms are more common in the unrelated gastroenteritis, which is sometimes called "stomach flu" or "24-hour flu".[3]
Typically, influenza is transmitted through the air by coughs or sneezes, creating aerosols containing the virus. Influenza can also be transmitted by bird droppings, saliva, nasal secretions, feces and blood. Infection can also occur through contact with these body fluids or through contact with contaminated surfaces. Airborne aerosols have been thought to cause most infections, although which means of transmission is most important is not absolutely clear. Influenza viruses can be inactivated by sunlight, disinfectants and detergents.[4][5] As the virus can be inactivated by soap, frequent hand washing reduces the risk of infection.
Influenza spreads around the world in seasonal epidemics, resulting in the deaths of hundreds of thousands annually — millions in pandemic years. Three influenza pandemics occurred in the 20th century and killed tens of millions of people, with each of these pandemics being caused by the appearance of a new strain of the virus in humans. Often, these new strains appear when an existing flu virus spreads to humans from other animal species, or when an existing human strain picks up new genes from a virus that usually infects birds or pigs. An avian strain named H5N1 raised the concern of a new influenza pandemic, after it emerged in Asia in the 1990s, but it has not evolved to a form that spreads easily between people.[6] In April 2009 a novel flu strain evolved that combined genes from human, pig, and bird flu, initially dubbed "swine flu", emerged in Mexico, the United States, and several other nations. WHO officially declared the outbreak to be a "pandemic" on June 11, 2009.Vaccinations against influenza are usually given to people in developed countries [7] and to farmed poultry.[8] The most common human vaccine is the trivalent influenza vaccine (TIV) that contains purified and inactivated material from three viral strains. Typically, this vaccine includes material from two influenza A virus subtypes and one influenza B virus strain.[9] The TIV carries no risk of transmitting the disease, and it has very low reactivity. A vaccine formulated for one year may be ineffective in the following year, since the influenza virus evolves rapidly, and new strains quickly replace the older ones. Antiviral drugs can be used to treat influenza, with neuraminidase inhibitors being particularly effective.
primila
Signs and symptoms
Symptoms of influenza,[43], with fever and cough the most common symptoms.[44]
Symptoms of influenza can start quite suddenly one to two days after infection. Usually the first symptoms are chills or a chilly sensation, but fever is also common early in the infection, with body temperatures ranging from 38-39 °C (approximately 100-103 °F).[45] Many people are so ill that they are confined to bed for several days, with aches and pains throughout their bodies, which are worse in their backs and legs.[1] Symptoms of influenza may include:
Body aches, especially joints and throat
Extreme coldness and fever
Fatigue
Headache
Irritated watering eyes
Reddened eyes, skin (especially face), mouth, throat and nose
In children, gastrointestinal symptoms such as diarrhoea and abdominal pain,[46][47] (may be severe in children with influenza B)[48]
It can be difficult to distinguish between the common cold and influenza in the early stages of these infections,[2] but a flu can be identified by a high fever with a sudden onset and extreme fatigue. Diarrhoea is not normally a symptom of influenza in adults,[44] although it has been seen in some human cases of the H5N1 "bird flu"[49] and can be a symptom in children.[46] The symptoms most reliably seen in influenza are shown in the table to the right.[44]
Most sensitive symptoms for diagnosing influenza[44]
Symptom:
sensitivity
specificity
Fever
68-86%
25-73%
Cough
84-98%
7-29%
Nasal congestion
68–91%
19–41%
Notes to table:
The ranges given represent different studies that were reviewed.
Sensitivity is the proportion of people having influenza who exhibit the symptom.
Specificity is the proportion of people not having influenza who do not exhibit the symptom.
All three findings, especially fever, were less sensitive in patients over 60 years of age.
Since anti-viral drugs are effective in treating influenza if given early (see treatment section, below), it can be important to identify cases early. Of the symptoms listed above, the combinations of fever with cough, sore throat and/or nasal conjestion can improve diagnostic accuracy.[50] Two decision analysis studies[51][52] suggest that during local outbreaks of influenza, the prevalence will be over 70%,[52] and thus patients with any of these combinations of symptoms may be treated with neuramidase inhibitors without testing. Even in the absence of a local outbreak, treatment may be justified in the elderly during the influenza season as long as the prevalence is over 15%.[52]
The available laboratory tests for influenza continue to improve. The United States Centers for Disease Control and Prevention (CDC) maintains an up-to-date summary of available laboratory tests.[53] According to the CDC, rapid diagnostic tests have a sensitivity of 70–75% and specificity of 90–95% when compared with viral culture. These tests may be especially useful during the influenza season (prevalence=25%) but in the absence of a local outbreak, or peri-influenza season (prevalence=10%[52]).
Symptoms of influenza,[43], with fever and cough the most common symptoms.[44]
Symptoms of influenza can start quite suddenly one to two days after infection. Usually the first symptoms are chills or a chilly sensation, but fever is also common early in the infection, with body temperatures ranging from 38-39 °C (approximately 100-103 °F).[45] Many people are so ill that they are confined to bed for several days, with aches and pains throughout their bodies, which are worse in their backs and legs.[1] Symptoms of influenza may include:
Body aches, especially joints and throat
Extreme coldness and fever
Fatigue
Headache
Irritated watering eyes
Reddened eyes, skin (especially face), mouth, throat and nose
In children, gastrointestinal symptoms such as diarrhoea and abdominal pain,[46][47] (may be severe in children with influenza B)[48]
It can be difficult to distinguish between the common cold and influenza in the early stages of these infections,[2] but a flu can be identified by a high fever with a sudden onset and extreme fatigue. Diarrhoea is not normally a symptom of influenza in adults,[44] although it has been seen in some human cases of the H5N1 "bird flu"[49] and can be a symptom in children.[46] The symptoms most reliably seen in influenza are shown in the table to the right.[44]
Most sensitive symptoms for diagnosing influenza[44]
Symptom:
sensitivity
specificity
Fever
68-86%
25-73%
Cough
84-98%
7-29%
Nasal congestion
68–91%
19–41%
Notes to table:
The ranges given represent different studies that were reviewed.
Sensitivity is the proportion of people having influenza who exhibit the symptom.
Specificity is the proportion of people not having influenza who do not exhibit the symptom.
All three findings, especially fever, were less sensitive in patients over 60 years of age.
Since anti-viral drugs are effective in treating influenza if given early (see treatment section, below), it can be important to identify cases early. Of the symptoms listed above, the combinations of fever with cough, sore throat and/or nasal conjestion can improve diagnostic accuracy.[50] Two decision analysis studies[51][52] suggest that during local outbreaks of influenza, the prevalence will be over 70%,[52] and thus patients with any of these combinations of symptoms may be treated with neuramidase inhibitors without testing. Even in the absence of a local outbreak, treatment may be justified in the elderly during the influenza season as long as the prevalence is over 15%.[52]
The available laboratory tests for influenza continue to improve. The United States Centers for Disease Control and Prevention (CDC) maintains an up-to-date summary of available laboratory tests.[53] According to the CDC, rapid diagnostic tests have a sensitivity of 70–75% and specificity of 90–95% when compared with viral culture. These tests may be especially useful during the influenza season (prevalence=25%) but in the absence of a local outbreak, or peri-influenza season (prevalence=10%[52]).
the history frm primila
History
Etymology
The word Influenza comes from the Italian language and refers to the cause of the disease; initially, this ascribed illness to unfavorable astrological influences.[125] 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.[126] Archaic terms for influenza include epidemic catarrh, grippe (from the French), sweating sickness, and Spanish fever (particularly for the 1918 pandemic strain).[127]
Pandemics
Further information: Influenza pandemic, Spanish flu, Hong Kong flu
The difference between the influenza mortality age distributions of the 1918 epidemic and normal epidemics. Deaths per 100,000 persons in each age group, United States, for the interpandemic years 1911–1917 (dashed line) and the pandemic year 1918 (solid line).[128]
The symptoms of human influenza were clearly described by Hippocrates roughly 2,400 years ago.[129][130] 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.[131]
The most famous and lethal outbreak was the 1918 flu pandemic (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.[132][133] This pandemic has been described as "the greatest medical holocaust in history" and may have killed as many people as the Black Death.[131] 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.[133] 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."[132] 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.[128]
The 1918 flu pandemic (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%.[128][132] 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.[134] 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.[132]
The influenza viruses that caused Hong Kong flu. (magnified approximately 100,000 times)
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.[128]
Known flu pandemics[131][32]
Name of pandemic
Date
Deaths
Subtype involved
Pandemic Severity Index
Asiatic (Russian) Flu
1889–1890
1 million
possibly H2N2
NA
1918 flu pandemic (Spanish flu)
1918–1920
20 to 100 million
H1N1
5
Asian Flu
1957–1958
1 to 1.5 million
H2N2
2
Hong Kong Flu
1968–1969
0.75 to 1 million
H3N2
2
2009 flu pandemic
2009–Present
NA
H1N1
NA
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.[135] The etiological cause of influenza, the Orthomyxoviridae family of viruses, was first discovered in pigs by Richard Shope in 1931.[136] 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.[137] However, it was not until Wendell Stanley first crystallized tobacco mosaic virus in 1935 that the non-cellular nature of viruses was appreciated.
The main types of influenza viruses in humans. Solid squares show the appearance of a new strain, causing recurring influenza pandemics. Broken lines indicate uncertain strain identifications.[138]
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.[139] 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.[140] 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.[132] 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.[33]
Society and culture
Influenza produces direct costs due to lost productivity and associated medical treatment, as well as indirect costs of preventative measures. In the United States, influenza is responsible for a total cost of over $10 billion per year, while it has been estimated that a future pandemic could cause hundreds of billions of dollars in direct and indirect costs.[141] 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.[142] Other studies have attempted to predict the costs of a pandemic as serious as the 1918 Spanish flu on the U.S. economy, where 30% of all workers became ill, and 2.5% were killed. A 30% sickness rate and a three-week length of illness would decrease the gross domestic product by 5%. Additional costs would come from medical treatment of 18 million to 45 million people, and total economic costs would be approximately $700 billion.[143]
Preventative costs are also high. 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.[144] On 1 November 2005, United States President George W. Bush unveiled the National Strategy to Safeguard Against the Danger of Pandemic Influenza[145] backed by a request to Congress for $7.1 billion to begin implementing the plan.[146] Internationally, on 18 January 2006, donor nations pledged US$2 billion to combat bird flu at the two-day International Pledging Conference on Avian and Human Influenza held in China.[147]
Dr. Terrence Tumpey examining a reconstructed 1918 Spanish Flu Virus at a CDC in a Biosafety level 3 environment.
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). These studies help in developing influenza countermeasures; for example, a better understanding of the body's immune system response helps vaccine development, and a detailed picture of how influenza invades cells aids the development of antiviral drugs. One important basic research program is the Influenza Genome Sequencing Project, which is creating a library of influenza sequences; this library should help clarify which factors make one strain more lethal than another, which genes most affect immunogenicity, and how the virus evolves over time.[148]
Research into new vaccines is particularly important, as current vaccines are very slow and expensive to produce and must be reformulated every year. The sequencing of the influenza genome and recombinant DNA technology may accelerate the generation of new vaccine strains by allowing scientists to substitute new antigens into a previously developed vaccine strain.[149] New technologies are also being developed to grow viruses in cell culture, which promises higher yields, less cost, better quality and surge capacity.[150] Research on a universal influenza A vaccine, targeted against the external domain of the transmembrane viral M2 protein (M2e), is being done at the University of Ghent by Walter Fiers, Xavier Saelens and their team[151][152][153] and has now successfully concluded Phase I clinical trials.
A number of biologics, therapeutic vaccines and immunobiologics are also being investigated for treatment of infection caused by viruses. Therapeutic biologics are designed to activate the immune response to virus or antigens. Typically, biologics do not target metabolic pathways like anti-viral drugs, but stimulate immune cells such as lymphocytes, macrophages, and/or antigen presenting cells, in an effort to drive an immune response towards a cytotoxic effect against the virus. Infuenza models, such as murine influenza, are convenient models to test the effects of prophylactic and therapeutic biologics. For example, Lymphocyte T-Cell Immune Modulator inhibits viral growth in the murine model of influenza.
Etymology
The word Influenza comes from the Italian language and refers to the cause of the disease; initially, this ascribed illness to unfavorable astrological influences.[125] 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.[126] Archaic terms for influenza include epidemic catarrh, grippe (from the French), sweating sickness, and Spanish fever (particularly for the 1918 pandemic strain).[127]
Pandemics
Further information: Influenza pandemic, Spanish flu, Hong Kong flu
The difference between the influenza mortality age distributions of the 1918 epidemic and normal epidemics. Deaths per 100,000 persons in each age group, United States, for the interpandemic years 1911–1917 (dashed line) and the pandemic year 1918 (solid line).[128]
The symptoms of human influenza were clearly described by Hippocrates roughly 2,400 years ago.[129][130] 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.[131]
The most famous and lethal outbreak was the 1918 flu pandemic (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.[132][133] This pandemic has been described as "the greatest medical holocaust in history" and may have killed as many people as the Black Death.[131] 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.[133] 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."[132] 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.[128]
The 1918 flu pandemic (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%.[128][132] 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.[134] 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.[132]
The influenza viruses that caused Hong Kong flu. (magnified approximately 100,000 times)
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.[128]
Known flu pandemics[131][32]
Name of pandemic
Date
Deaths
Subtype involved
Pandemic Severity Index
Asiatic (Russian) Flu
1889–1890
1 million
possibly H2N2
NA
1918 flu pandemic (Spanish flu)
1918–1920
20 to 100 million
H1N1
5
Asian Flu
1957–1958
1 to 1.5 million
H2N2
2
Hong Kong Flu
1968–1969
0.75 to 1 million
H3N2
2
2009 flu pandemic
2009–Present
NA
H1N1
NA
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.[135] The etiological cause of influenza, the Orthomyxoviridae family of viruses, was first discovered in pigs by Richard Shope in 1931.[136] 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.[137] However, it was not until Wendell Stanley first crystallized tobacco mosaic virus in 1935 that the non-cellular nature of viruses was appreciated.
The main types of influenza viruses in humans. Solid squares show the appearance of a new strain, causing recurring influenza pandemics. Broken lines indicate uncertain strain identifications.[138]
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.[139] 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.[140] 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.[132] 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.[33]
Society and culture
Influenza produces direct costs due to lost productivity and associated medical treatment, as well as indirect costs of preventative measures. In the United States, influenza is responsible for a total cost of over $10 billion per year, while it has been estimated that a future pandemic could cause hundreds of billions of dollars in direct and indirect costs.[141] 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.[142] Other studies have attempted to predict the costs of a pandemic as serious as the 1918 Spanish flu on the U.S. economy, where 30% of all workers became ill, and 2.5% were killed. A 30% sickness rate and a three-week length of illness would decrease the gross domestic product by 5%. Additional costs would come from medical treatment of 18 million to 45 million people, and total economic costs would be approximately $700 billion.[143]
Preventative costs are also high. 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.[144] On 1 November 2005, United States President George W. Bush unveiled the National Strategy to Safeguard Against the Danger of Pandemic Influenza[145] backed by a request to Congress for $7.1 billion to begin implementing the plan.[146] Internationally, on 18 January 2006, donor nations pledged US$2 billion to combat bird flu at the two-day International Pledging Conference on Avian and Human Influenza held in China.[147]
Dr. Terrence Tumpey examining a reconstructed 1918 Spanish Flu Virus at a CDC in a Biosafety level 3 environment.
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). These studies help in developing influenza countermeasures; for example, a better understanding of the body's immune system response helps vaccine development, and a detailed picture of how influenza invades cells aids the development of antiviral drugs. One important basic research program is the Influenza Genome Sequencing Project, which is creating a library of influenza sequences; this library should help clarify which factors make one strain more lethal than another, which genes most affect immunogenicity, and how the virus evolves over time.[148]
Research into new vaccines is particularly important, as current vaccines are very slow and expensive to produce and must be reformulated every year. The sequencing of the influenza genome and recombinant DNA technology may accelerate the generation of new vaccine strains by allowing scientists to substitute new antigens into a previously developed vaccine strain.[149] New technologies are also being developed to grow viruses in cell culture, which promises higher yields, less cost, better quality and surge capacity.[150] Research on a universal influenza A vaccine, targeted against the external domain of the transmembrane viral M2 protein (M2e), is being done at the University of Ghent by Walter Fiers, Xavier Saelens and their team[151][152][153] and has now successfully concluded Phase I clinical trials.
A number of biologics, therapeutic vaccines and immunobiologics are also being investigated for treatment of infection caused by viruses. Therapeutic biologics are designed to activate the immune response to virus or antigens. Typically, biologics do not target metabolic pathways like anti-viral drugs, but stimulate immune cells such as lymphocytes, macrophages, and/or antigen presenting cells, in an effort to drive an immune response towards a cytotoxic effect against the virus. Infuenza models, such as murine influenza, are convenient models to test the effects of prophylactic and therapeutic biologics. For example, Lymphocyte T-Cell Immune Modulator inhibits viral growth in the murine model of influenza.
Friday, July 17, 2009
The Project - A Influenza H1N1 ( Ru Yi )
According to Word Web , "Influenza" means an acute febrile highly contagious viral disease . It is also synonyms as flu . Therefore , A Influenza H1N1 is also consider as a flu disease .
I found some information from http://thestar.com.my/news/story.asp?file=/2009/4/28/nation/20090428132524&sec=nation . Below are some of the information from the page :
The defination of A (H1N1) Influenza is respiratory disease of pigs caused by type A strains of the influenza virus. It regularly causes high flu outbreaks in pigs but with low death rates. There are four main sub-types of the virus, but the most recent isolated influenza viruses from pigs have been H1N1 viruses. However, Influenza A (H1N1) viruses do not typically infect humans though they do occur through close proximity or contact with infected pigs or contaminated areas. Cases of human-to-human spread have been documented.
The symptoms of A (H1N1) Influenza are similar to those of regular flu such as fever, lethargy, runny nose, cough, sore throat, lack of appetite, vomiting and even diarrhoea in some cases.
This strain of disease is not seen before . Flu mutates constantly, so it is common for new strains to emerge. Pigs can also be infected with both human and avian influenza, and the current circulating A (H1N1) flu strain appears to contain genetic elements from all three.
So far , the A (H1N1) flu is resistant to two common drugs which are Amantadine and Rimantadine. The A (H1N1) flu viruses are very different from human H1N1 viruses. Therefore, vaccines for human seasonal flu would not provide protection. However, a “seed vaccine” has been specifically tailored to this swine flu and will be manufactured if officials deem it necessary.
People with the A (H1N1) influenza virus infection should be considered potentially contagious as long as they are symptomatic. It is possible for them to be constagious for up to seven days following the onset of the illness. Children, especially younger children, might potentially be contagious for longer periods.Yet,there is no vaccine available right now to protect against the A (H1N1) flu.
We can help prevent the spread of germs that cause respiratory illnesses like influenza by covering our nose and mouth with a disposable tissue or handkerchief when we cough or sneeze and throw the tissue in the waste basket after we use it. Secondly,wash our hands often with soap and water, especially after we cough or sneeze. Alcohol-based hand cleaners are also helpful too . Thirdly, try to avoid close contact with sick people. If he or she gets sick with influenza, stay at home and limit contact with others to prevent the disease from infecting them. Next, avoid touching our eyes, nose or mouth. Then, consult our nearest healthcare facility if you think you have any of the symptoms.
In Malaysia, the Health Ministry’s operations room in Putrajaya has started a 24-hour monitoring of the situation. The public can call 03-8881 0200/300 for enquiries. For those who just returned from Latin American countries and found to have flu-like symptoms will be quarantined. Besides , health ministry officials are conducting health screenings on passengers arriving from the United States.Thermal scanners will be placed at international airports to speed up the screening process for A (H1N1) flu. Furthermore, public and private medical practitioners have been instructed to report to the district health office if any patient with influenza-like illnesses or severe pneumonia symptoms and who had travelled to the affected countries after April 17.
For more information, please visit the Health Ministry (http://www.moh.gov.my/) or call the Ministry's hotline at (03) 8881-0200/300.
I found some information from http://thestar.com.my/news/story.asp?file=/2009/4/28/nation/20090428132524&sec=nation . Below are some of the information from the page :
The defination of A (H1N1) Influenza is respiratory disease of pigs caused by type A strains of the influenza virus. It regularly causes high flu outbreaks in pigs but with low death rates. There are four main sub-types of the virus, but the most recent isolated influenza viruses from pigs have been H1N1 viruses. However, Influenza A (H1N1) viruses do not typically infect humans though they do occur through close proximity or contact with infected pigs or contaminated areas. Cases of human-to-human spread have been documented.
The symptoms of A (H1N1) Influenza are similar to those of regular flu such as fever, lethargy, runny nose, cough, sore throat, lack of appetite, vomiting and even diarrhoea in some cases.
This strain of disease is not seen before . Flu mutates constantly, so it is common for new strains to emerge. Pigs can also be infected with both human and avian influenza, and the current circulating A (H1N1) flu strain appears to contain genetic elements from all three.
So far , the A (H1N1) flu is resistant to two common drugs which are Amantadine and Rimantadine. The A (H1N1) flu viruses are very different from human H1N1 viruses. Therefore, vaccines for human seasonal flu would not provide protection. However, a “seed vaccine” has been specifically tailored to this swine flu and will be manufactured if officials deem it necessary.
People with the A (H1N1) influenza virus infection should be considered potentially contagious as long as they are symptomatic. It is possible for them to be constagious for up to seven days following the onset of the illness. Children, especially younger children, might potentially be contagious for longer periods.Yet,there is no vaccine available right now to protect against the A (H1N1) flu.
We can help prevent the spread of germs that cause respiratory illnesses like influenza by covering our nose and mouth with a disposable tissue or handkerchief when we cough or sneeze and throw the tissue in the waste basket after we use it. Secondly,wash our hands often with soap and water, especially after we cough or sneeze. Alcohol-based hand cleaners are also helpful too . Thirdly, try to avoid close contact with sick people. If he or she gets sick with influenza, stay at home and limit contact with others to prevent the disease from infecting them. Next, avoid touching our eyes, nose or mouth. Then, consult our nearest healthcare facility if you think you have any of the symptoms.
In Malaysia, the Health Ministry’s operations room in Putrajaya has started a 24-hour monitoring of the situation. The public can call 03-8881 0200/300 for enquiries. For those who just returned from Latin American countries and found to have flu-like symptoms will be quarantined. Besides , health ministry officials are conducting health screenings on passengers arriving from the United States.Thermal scanners will be placed at international airports to speed up the screening process for A (H1N1) flu. Furthermore, public and private medical practitioners have been instructed to report to the district health office if any patient with influenza-like illnesses or severe pneumonia symptoms and who had travelled to the affected countries after April 17.
For more information, please visit the Health Ministry (http://www.moh.gov.my/) or call the Ministry's hotline at (03) 8881-0200/300.
Monday, July 13, 2009
Just Testing by Ru Yi
I'm just testing this blog caused this is the first time I'm using it . Hope you guys like the settings .
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