Every one is at risk of developing influenza and over 100 million people are affected each year in Europe, Japan and the USA alone. A bad case of the influenza will probably send a healthy adult or child to bed for 3 to 5 days. Afterwards, the person will recover fully, but cough and tiredness may persist for days or weeks.

Influenza can also be a life-threatening illness, with hundreds of thousands hospitalised each year. Influenza and its complications have caused up to 40,000 deaths each year in the US alone and in a typical winter in the UK, 3,000 to 4,000 deaths are attributed to influenza. During one of the worst epidemics, the "Spanish Flu" that swept the entire world from 1918 to 1920, at least 20 million people died.

People over the age of 50 and those of all ages with chronic illnesses (such as diabetes, heart disease, asthma and HIV) are more likely to become seriously ill with the flu and go on to develop other infections such as pneumonia and sinusitis.

What is Influenza?
Influenza is a virus that infects the upper and lower respiratory tract: the nose, sinuses, throat, lungs and middle ear. It typically occurs in the autumn and winter months in the Northern (October through to April) and Southern (April to September) hemispheres and is characterised by explosive outbreaks that last for 6 to 8 weeks.

Influenza is highly contagious. The virus usually enters the body through mucous membranes in the mouth, nose or eyes. When a person with the flu coughs or sneezes, the virus becomes airborne and can be inhaled by anyone nearby. The incubation period ranges from 18 to 72 hours during which time the infected person is already likely to spread the virus to other people.

The onset of flu often seems sudden and people describe feeling like "they've been hit by a truck." Common flu symptoms include fever and chills, cough, muscle and joint pain, headache, fatigue and weakness.

Current Management of Influenza
To prevent getting influenza, certain patient groups can get vaccinated each year - particularly the elderly or those with chronic health problems. But the influenza vaccine is not always effective because the flu strains it protects against may not be the same as the ones that are going around that year.

Most people rely on over-the-counter treatments and remedies to try and reduce some of the symptoms associated with influenza, but these do not stop the virus from spreading.

Investigators have recently discovered a new class of drugs - neuraminidase inhibitors that attack the virus, the root cause of the influenza infection.