Influenza  (Flu)


Influenza surveilance statistics; graphs, charts, and maps.  See where the flu is spreading, which states
are effected, and how many cases have been reported.

Influenza Basics
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.

     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 produce nausea and vomiting, especially 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, 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 for much longer periods at very low temperatures. Most influenza strains can be inactivated easily by disinfectants and detergents

     Flu 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. Each of these pandemics was caused by the appearance of a new strain of the virus in humans. Often new strains of flu virus result from the spread of an existing flu virus to humans from other animal species.

     Vaccinations against influenza are usually given to people in developed countries and to farmed poultry. 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. 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 different strains become dominant. Antiviral drugs can be used to treat influenza, with neuraminidase inhibitors being particularly effective.

     20th Century Pandemics:              
             1918    - Originated in Europe        click here for more information
             1968     - Originated in Hong Kong    click here for more information
             1990's - Originated in Asia             click here for more information

     Click here for more information on the current flu outbreak

Flu (Influenza)  Dictionary

 
Avian Flu (influenza)\ ey-vee-uhn\ from Latin avis, of, relating to, or derived from birds +ˈflü\ by shortening; avian flu (AL) is caused by influenza viruses that ocur naturally among wild birds. Low pathogenic AI is common in birds and causes few problems. Highly pathogenic H5N1 (H1N1) is deadly to domestic fowl, can be transmitted from birds to humans, and is deadly to humans. There is virtually no human immunity and human vaccine availability is very limited.

Bird Flu \ˈbərd\from English a feathered vertebrate + ˈflü\ by shortening\"avian influenza"; a severe, often fatal influenza A infection caused by strains of a subtype (H5N1)/(H1N1) of the causative orthomyxovirus that have produced epidemics in domestic birds especially in Asia with sporadic associated human infections. Typically, migratory birds are common hosts of the virus; do not become infected themselves; infect domestic birds, including chickens, other poultry.  Bird flu is commonly referred to as Avian flu (see above).

Epidemic \ ep·i·dem·ic \ e-pə-ˈde-mik\from Greek epi- + dēmos people; affecting or tending to affect a disproportionately large number of individuals within a population, community, or region at the same time.

H1N1 Virus \scientific notation + vahy-ruhs\from Latin, vīrus, slime, poison; akin to slime\ H1N1 Influenza (H1N1flu); a  type A influenza virus.  Type A viruses cause regular outbreaks of respiratory diseases in pigs. People do not normally get swine flu, but human infections can and do occur. This new virus was first detected in the U.S. in April 2009, and has spread to many countries around the world.

Influenza \in·flu·en·za\ in-(ˌ)flü-ˈen-zə\ Italian, literally, influence, from Medieval Latin influentia; from the belief that epidemics were due to the influence of the stars.  Modern day Englsih slang," flu."

Pandemic \pan-'dem-ik\from Greek παν \pan all + δήμος demos, of all the people; a global disease outbreak. An influenza pandemic occurs when a new influenza A virus emerges for which there is little or no immunity in the human population, begins to cause serious illness, and then spreads easily person-to-person worldwide.

Pandemic Flu: \pan-'dem-ik\from Greek παν pan all + δήμος demos, of all the people + ˈflü\ by shortening \ pandemic flu is virulent human flu that causes a global outbreak, or pandemic, of serious illness. Because there is little natural immunity, the disease can spread easily from person to person. A global flu outbreak. 

Seasonal Flu \sea·son·al \ˈsēz-nəl, ˈsē-zən-əl + ˈflü\ by shortening \ of, relating to, or varying in occurrence according to the season (time of year). Seasonal (or common) flu is a respiratory illness that can be transmitted person to person. Most people have some immunity, and a vaccine is available.

Type A Influenza Virus \scientific notation\new virus strains ( in virus (biology); influenza viruses that infect birds are called avian "A" influenza viruses. Only influenza A viruses (and all known subtypes of influenza A viruses) infect birds. There are significant genetic differences between the subtypes that typically infect both people and birds. Within the  subtypes of avian influenza A viruses there are different strains.  Influenza A viruses that infect humans can undergo a dramatic antigenic change, called antigenic shift, which generates viruses that cause pandemics.

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