Influenza, or flu, is a respiratory illness caused by a virus. Flu is highly contagious and is normally spread by the coughs and sneezes of an infected person. Although very unpleasant, flu is rarely life-threatening. You can also catch flu by touching an infected person by shaking hands for example. Adults are contagious 1-2 days before getting symptoms and up to 7 days after becoming ill. This means that you can spread the influenza virus before you even know you are infected.
Source
Signs and symptoms
Seasonal
influenza is characterized by a sudden onset of fever, cough, headache, muscle and joint pain, severe malaise, sore throat and a runny nose. The cough can be severe and can last 2 or more weeks. Most people recover from fever and other symptoms within a week without requiring medical attention. But influenza can cause severe illness or death especially in people at high risk.
Illnesses range from mild to severe and even death in some cases. Hospitalization and death occur mainly among high risk groups. Worldwide, these annual epidemics are estimated to result in about 3 to 5 million cases of severe illness, and about 290 000 to 650 000 deaths. The effects of seasonal influenza epidemics in developing countries are not fully known, but research estimates that 99% of deaths in children under 5 years of age with
influenza related lower respiratory tract infections are found in developing countries.
Causes
There are many different strains of the flu virus, and they mutate often. This is why people continue to come down with the flu year after year. The flu is a very contagious illness that spreads easily. Coughs and sneezes are strong enough to transmit droplets from the mouth and nose. You can also get the flu through personal contact, saliva, and by touching contaminated surfaces such as doorknobs or faucets. When someone else breathes in those respiratory droplets or touches any contaminated object and then touches their nose, mouth, or eyes, the virus spreads. A person is contagious with the flu from one day before symptoms appear to up to five days after becoming sick.
