|Abstract||Influenza (flu) is a highly infectious disease caused by influenza viruses. There are three types of influenza virus: A, B and C. Influenza A and B viruses cause virtually all of the clinical illness. The symptoms of influenza C infection are usually mild. Flu occurs every year mainly during the winter months. |
The influenza virus attacks the respiratory tract (the ear, nose and throat). The virus is mainly spread by respiratory droplets in the air produced by coughing or sneezing. It can also be spread by, for example, hand to eye contact after touching the respiratory droplets on another person or object. The incubation period before onset of symptoms is between one and three days.
Although most people recover from flu within a week, for some people the infection is more serious and leads to complications. These illnesses may require treatment in hospital and can be life-threatening especially in the elderly, people with heart or chest disease and those in poor health.
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