!INFLUENZA Influenza is a viral infection that affects mainly the nose, throat, bronchi and, occasionally, lungs. Infection usually lasts for about a week, and is characterized by sudden onset of high fever, aching muscles, headache and severe malaise, non-productive cough, sore throat and rhinitis. The virus is transmitted easily from person to person via droplets and small particles produced when infected people cough or sneeze. Influenza tends to spread rapidly in seasonal epidemics. Most infected people recover within one to two weeks without requiring medical treatment. However, in the very young, the elderly, and those with other serious medical conditions, infection can lead to severe complications of the underlying condition, pneumonia and death. Pandemic (H1N1) 2009 is a new influenza virus that has never circulated among humans before. After outbreaks in North America early in 2009, the virus spread rapidly around the world. Pandemic influenza is transmitted like seasonal influenza but people have virtually no immunity to it. Mitigating its effects is a public health priority. It is considered an epidemic disease, closely resembles, but is quite distinct from, cold in the head. It is characterised by early and marked debility and depression; though usually of short duration, attacks must not be disregarded; fatal results often ensue on carelessness. Convalescence is slow, and complications may ensue. The cause of the malady is viral infection; sporadic cases always occur, but from time to time great epidemics of this disease have travelled westward over the world. Their movement seems to depend on atmospheric conditions, but is independent of the season of the year and often contrary to the direction of the wind. Visitations occurred in Britain in 1837-38, 1847-48, and 1889-91.