Flu, or influenza, is a very contagious, acute, viral respiratory infection. Influenza viruses vary in a high degree. The extent of the genetic mutations vary each year, and the degree of protection in the population varies and influenza epidemics of variable intensity will occur.
Symptoms of influenza
Influenza incubation period can last from one to four days before the symptoms start to show up. Infected person starts feeling mild headache, fever with malaise, overall muscle weakness, possible sore throat and dry cough. It usually lasts for seven days.
The most common complication that usually is connected with influenza is pneumonia. It affects children and the elderly the most, as well as patients with certain chronic diseases. More difficult cases can be potentially life threatening.
There are treatments available which are most effective when given in time, which is in earliest possible stages.
Influenza is very contageous
From the day before symptoms begin, the incubation can be contageous. Furthermore, children can be infectious for more than 10 days after the symptoms begin to appear. A data from World Health Organization (WHO) fact sheet N°211 April 2009, shows that >72% of the passengers catch the disease when travelling with an infected passenger or on an airplane.
Epidemiology and vaccination against influenza
Influenza viruses transmit through the inhalation of respiratory droplets or contact with respiratory secretions. According to an estimate by WHO, each year between 250,000 and 500,000 people die due to influenza. There are several types of vaccine available for it. Vaccines are adapting each year to treat the most dominant circulating strains.