DEFINITIONS Influenza (flu) is a viral infection that causes fever, runny nose, headache, Flucough, not feeling well (malaise) and inflammation of the mucous membranes of the nose and respiratory tract. CAUSE Influenza virus type A or B. The virus is transmitted through infected saliva comes out when the patient coughs or sneezes, or through direct contact with secretions (saliva, saliva,… (more…)