The word flu is the shortened form of influenza. Influenza virus causes the flu. There are three main types of virus; Influenza virus A (can infects human and birds), Influenza virus B (infects only human) and Influenza virus C (can infect Human, dogs and pigs). These viruses are called RNA viruses, that means they have the genetic matter in the RNA. There are sub types in each virus. they are called serotypes. However the Influenza A virus got popularity as the sub groups of this virus caused more dangerous infection and caused deaths. Swine flu (Influenza A, H1N1 sub type) is one of the flu infection that spread widely in 2009. Its was a pandemic influenza.
Usually flu is a seasonal infection. During winter it spreads. This can spread from the patient to another normal individual by droplets. When a person cough or sneeze this virus will be released in the air and inhaled by the other people and infect them. So using mask and using handkerchief while sneezing will reduce the infection from one to another.
Flu is a self limiting infection. The viral infection will settle spontaneously with out any treatment. The infected person may develop common cold, fever, cough, body ache, headache and sore throat. In serious illness they may develop pneumonia (Lung infection).
H1N1 is a serotype of the influenza virus which got the popularity last year. However H1N1 stain(sub group) is rarely caused death compared with H5N1 (another serotype of Influenza A).
H1N1 influenza share all the characteristics of the flu, but unlike other flu, its spread all over the world causing pandemic infection. The list below will show the pandemics of influenza virus that occurred early.
H1N1, which caused Spanish Flu in 1918, and Swine Flu in 2009
H2N2, which caused Asian Flu in 1957
H3N2, which caused Hong Kong Flu in 1968
H5N1, which caused Bird Flu in 2004
H7N7, which has unusual zoonotic potential
H1N2, endemic in humans, pigs and birds
Simple measures can reduce the infection rate; good ventilation, sunlight and washing hands regularly have proofed to reduce the infection spreading from one to another. During pandemics the mask was used.
Treatment for flu is mainly supportive. Vaccine is available for flu. But the duration of this immune protection is for short period (1 or 2 years) because the virus changes time to time.
Finally, the flu is a common seasonal viral infection and H1N1 is the type of flu which may cause death.