Negatively stained flu virions. These were the causative agent of the Hong Kong Flu pandemic.
Find information on thousands of medical conditions and prescription drugs.


Influenza (or as it is commonly known, the flu or the grippe) is a contagious disease of the upper airways and the lungs, caused by an RNA virus of the orthomyxoviridae family. It rapidly spreads around the world in seasonal epidemics, imposing considerable economic burden, in the form of health care costs and lost productivity. Three influenza pandemics in the 20th century, each following a major genetic change in the virus, killed millions of people. more...

ICF syndrome
Ichthyosis vulgaris
Imperforate anus
Inborn error of metabolism
Incontinentia pigmenti
Infant respiratory...
Infantile spinal muscular...
Infective endocarditis
Inflammatory breast cancer
Inguinal hernia
Interstitial cystitis
Iodine deficiency
Irritable bowel syndrome

The term influenza has its origins in 15th century Italy, where the cause of the disease was ascribed to unfavorable astrological influences. Evolution in medical thought led to its modification to "influenza di freddo" (meaning "influence of the cold"), which by the 18th century became the prevalent terminology in the English-speaking world as well.


There are three genera of the virus, identified by antigenic differences in their nucleoprotein and matrix protein:

  • Influenza A viruses are known to infect humans, other mammals and birds (see also avian influenza) The annual flu vaccine is made by combining new versions of influenza A viruses that nature produces each year.
  • Influenza B viruses are known to infect humans and seals
  • Influenza C viruses are known to infect humans and pigs .

The A type of influenza virus, also called avian flu virus, is the type most likely to cause epidemics and pandemics. This is because the influenza A virus can undergo antigenic shift and present a new, immune target to susceptible people. Populations tend to have more resistance to influenza B and C, because they only undergo antigenic drift, and have more similarity with previous strains.

The avian flu virus is a species of virus. Its genetic code is RNA not DNA. It mutates very fast by comparison to both DNA and non-viruses. Cold preserves it while heat destroys it. It mutates enough so after a year of mutating in birds, humans can catch the new strain and not be protected by their body from last year's strain. Cold preserves it enough so in the winter it can pass from bird to human to human without being destroyed by heat. Sometimes an avian virus strain mutates into a very deadly version. H5N1 did just that.

Influenza A viruses can be further classified, based on the viral surface proteins hemagglutinin (HA or H) and neuraminidase (NA or N) that are essential to the virus' life cycle. Sixteen H subtypes and nine N subtypes have been identified for influenza A virus. Only one H subtype and one N subtype have been identified for influenza B virus. At present, the most common antigenic variants of influenza A virus are H1N1 and H3N2 (Yohannes et al., 2004).

Yet further variation exists; thus, specific influenza strain isolates are identified by a standard nomenclature specifying virus type, geographical location where first isolated, year of isolation, sequential number of isolation, and HA and NA subtype (Yohannes et al., 2004) Examples of the nomenclature are A/Moscow/10/99 (H3N2) and B/Hong Kong/330/2001.

The term superflu is used to refer to a strain of flu that spreads unusually quickly, is unusually virulent, or for which the host is uncommonly unresponsive to treatment— the kinds of strains which cause epidemics or pandemics. There is no exact scientific definition of a superflu.


[List your site here Free!]

The Great Influenza: The Epic Story of the Deadliest Plague In History $9.48 The Bird Flu Preparedness Planner $3.07
The Monster at Our Door: The Global Threat of Avian Flu $14.23 The Germ Freak's Guide to Outwitting Colds and Flu : Guerilla Tactics to Keep Yourself Healthy at Home, at Work and in the World $7.44
Wickett's Remedy : A Novel $8.84 Flu : The Story Of The Great Influenza Pandemic $3.95
The Homeopathic Treatment of Influenza - Special Bird Flu Edition: Surviving Influenza Epidemics And Pandemics Past, Present, And Future With Homeopathy $39.95 America's Forgotten Pandemic : The Influenza of 1918 $27.26
The Good Doctor's Guide to Colds and Flu $9.31 Heartland #13 (Heartland) $2.25

The causes of racial and ethnic differences in influenza vaccination rates among elderly medicare beneficiaries
Objective. To explore three potential causes of racial/ethnic differences in influenza vaccination rates in the elderly: (1) resistant attitudes and beliefs regarding vaccination by African-American
Influenza and pneumococcal vaccination demand responses to changes in infectious disease mortality
Objective. To test the hypothesis that individuals are more likely to receive a vaccination against influenza or pneumonia as the perceived disease threat ...
Influenza virus infection in racing greyhounds
To the Editor: Influenza is globally the most economically important respiratory disease in humans, pigs, horses, and fowl (1). Influenza virus is known ...
Avian influenza virus could kill millions
A harmless virus used as a delivery vehicle may help set a roadblock for a potentially catastrophic outbreak of bird flu in humans, assert researchers ...
Influenza vaccination & elderly
Increasing the number of people, ages 65 and older, who receive influenza vaccinations has not reduced flu-related deaths, according to a 2005 study ...
Remarks on the national strategy for pandemic influenza preparedness and Response in Bethesda, Maryland
November 1, 2005 Thank you all. Michael, thank you very much for your introduction. And thanks for the warm reception here at the National Institute ...
Diagnosing and treating patients with suspected influenza
Clinical Question What is the best approach to diagnosing and treating a patient with suspected influenza? Evidence Summary During the winter months, influenza is one of the most common illne
Letter to the Speaker of the House of Representatives on funding for the national strategy for pandemic influenza preparedness and response
November 1, 2005 Dear Mr. Speaker: Today, I outlined a strategy to address the threat of avian and pandemic influenza. This strategy is designed ...

Home Contact Resources Exchange Links ebay