Influenza is an acute viral disease which spreads through droplets. Its characteristic feature is sudden onset. The first symptoms appear within ca. 48 hours of the infection. They include high fever, even to 39.5o C, chills, bone and joint pain in the area of the back and the legs, photophobia, asthenia and headaches. In some patients, especially in children, diarrhoea and abdominal pain may occur. Dry tiring cough accompanied by sore throat and runny nose appears.