fp: influenza type a

Sejak Jumaat lepas…mula2 Zakwan yg kena influenza type A. Bangun je pagi2 dah terasa panas badan dan terus bwk pergi klinik. Lepas guna tester dan confirm infected. Last week, Selasa dan Rabu, tadika Alya dan Zakwan cuti dua hari sbb ada > 20 org kids yg kena influenza. So tak sure sejak bila Zakwan infected. And last weekend, tak dpt nak tunaikan jemputan birthday party anak Herman and Ida @ Tostuka. Dan smlm lepas balik dari lab, mama, Alya dan Zarul pulak confirm infected. So papa je yg belum kena or maybe dah kena. Jikan no mondai desu. Terasa jugak pening2 but tak sure pening dgn research or influenza. Wait and see. But hopefully tak kena la sbb byk sgt kerja yg nak kena settlekan. Dengan research, journal paper, final report for research assistant etc. So doakanlah kami semua sihat. And here few info on influenza.

Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae (the influenza viruses). In humans, common symptoms of influenza are fever, sore throat, muscle pains, severe headache, coughing, weakness and general discomfort. In more serious cases, influenza causes pneumonia, which can be fatal, particularly in young children and the elderly. Sometimes confused with the common cold, influenza is a much more severe disease and is caused by a different type of virus. Although nausea and vomiting can be produced, especially in children, these symptoms are more characteristic of the unrelated 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, faeces 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 indefinitely at very low temperatures (such as lakes in northeast Siberia). Most influenza strains can be inactivated easily by disinfectants and detergents.

Flu spreads around the world in seasonal epidemics, killing millions of people in pandemic years and hundreds of thousands in non-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 result from the spread of an existing flu virus to humans from other animal species. A deadly avian strain named H5N1 has posed the greatest risk for a new influenza pandemic since it first killed humans in Asia in the 1990s. Fortunately, this virus has not mutated to a form that spreads easily between people.

Vaccinations against influenza are usually given to people in industrialized countries with a high risk of contracting the disease, and to farmed poultry. The most common human vaccine is the trivalent influenza vaccine 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. A vaccine formulated for one year may be ineffective in the following year, since the influenza virus changes rapidly over time and different strains become dominant. Antiviral drugs can be used to treat influenza, with neuraminidase inhibitors being particularly effective.

The term influenza has its origins in 15th-century Italy, where the cause of the disease was ascribed to unfavourable astrological influences. Evolution 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 borrowed 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 2400 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 Asia 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. Older estimates say it killed 40–50 million people while current estimates say 50 million to 100 million people worldwide were killed. 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 Schope 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 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 New Jersey in 1976 (with the Swine Flu), world wide 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.

Types of influenza virus
Structure of the influenza virion. The hemagglutinin (HA) and neuraminidase (NA) proteins are shown on the surface of the particle. The viral RNAs that make up the genome are shown as red coils inside the particle and bound to Ribonuclear Proteins (RNPs).
Structure of the influenza virion. The hemagglutinin (HA) and neuraminidase (NA) proteins are shown on the surface of the particle. The viral RNAs that make up the genome are shown as red coils inside the particle and bound to Ribonuclear Proteins (RNPs).

The influenza virus is an RNA virus of the family Orthomyxoviridae, which comprises the influenzaviruses Isavirus and Thogotovirus. There are three types of influenza virus: Influenzavirus A, Influenzavirus B, and Influenzavirus C. Influenza A and C infect multiple species, while influenza B almost exclusively infects humans. Wild aquatic birds are the natural hosts for a large variety of influenza A viruses. Occasionally viruses are transmitted to other species and may then cause devastating outbreaks in domestic poultry or give rise to human influenza pandemics. The type A viruses are the most virulent human pathogens among the three influenza types and cause the most severe disease. The Influenza A virus can be subdivided into different serotypes based on the antibody response to these viruses. The serotypes that have been confirmed in humans, ordered by the number of known human pandemic deaths, are:

* H1N1 caused “Spanish Flu.”
* H2N2 caused “Asian Flu.”
* H3N2 caused “Hong Kong Flu.”
* H5N1 is a pandemic threat in 2007–8 flu season.
* H7N7 has unusual zoonotic potential.
* H1N2 is endemic in humans and pigs.
* H9N2, H7N2, H7N3, H10N7.

Influenza B virus is almost exclusively a human pathogen and is less common than influenza A. The only other animal known to be susceptible to influenza B infection is the seal. This type of influenza mutates at a rate 2–3 times lower than type A and consequently is less genetically diverse, with only one influenza B serotype. As a result of this lack of antigenic diversity, a degree of immunity to influenza B is usually acquired at an early age. However, influenza B mutates enough that lasting immunity is not possible. This reduced rate of antigenic change, combined with its limited host range (inhibiting cross species antigenic shift), ensures that pandemics of influenza B do not occur.

The influenza C virus infects humans and pigs, and can cause severe illness and local epidemics. However, influenza C is less common than the other types and usually seems to cause mild disease in children.

odaijini sensei & femly Wed 30-Jan-2008 09:40
Posted by:ah desu~

odaijini.. saya baru tau lepas pagi tadi rizafiza sensei call. terkejut saya. baru tgh pikir2 nak cari masa gi umah sensei. take care ye semua… jaga diri elok2 Wed 30-Jan-2008 10:14
Posted by:hanis

terima kasih byk2…take time gak nak recover ni…so kena kuarantin la dlm seminggu dua ni.. Wed 30-Jan-2008 11:26
Posted by:nash nzainal@hotmail.com

Hola…ingat saya tak?lama sungguh not keep in touch..you are mummy now Wed 30-Jan-2008 18:40
Posted by:pahcik sharna_sy@yahoo.com

Rizafizah-email me once you read this message- Wed 30-Jan-2008 18:43
Posted by:pahcik sharna_sy@yahoo.com

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