Influenza

Influenza, briefly known as flu, is an acute respiratory infectious disease caused by influenza virus. It spreads via droplets, with strong infectivity. Its incident rate ranks first in legal infectious diseases, with occurrences of outbreaks or pandemics. Its clinical symptoms are characterized by acute onset of high fever, fatigue, systemic muscular soreness and pain, as well as mild respiratory tract symptoms. Influenza more commonly occurs in autumns and winters. Although it has a short disease course and is self-limited, it may be complicated by pneumonia and other serious complications in populations including the elderly, infants and young children, patients with cardiac or pulmonary diseases, patients with other chronic diseases, and patients with compromised immunity. In some serious cases, death may even occur.