Influenza is a disease of the lungs and upper airways caused by infection with a flu virus, which spreads in the lungs and airways.
There are three flu viruses, known as A, B and C.
The flu virus is usually spread in the small droplets of saliva coughed or sneezed into the atmosphere by an infected person. Direct contact with hands contaminated with the virus can also spread infection.
It takes 1–4 days (average is 2 days) to go from being infected to having the full symptoms.
Flu usually occurs during the winter months, from October to April in the UK.
The main symptoms are:
- high temperature that comes on quickly
- general aches and pains
- a loss of appetite
- a harsh dry cough.
Symptoms will usually peak after 2–3 days and the patient should be much better within 5–8 days, although a cough and general tiredness may last for 2–3 weeks.