This is a highly infectious disease caused by a virus that affects the respiratory tract. The symptoms include headache, weakness, fever, sneezing and coughing, sore throat, aches and pains in limbs and joints, and loss of appetite.

It is usually caused by one of three main strains of the influenza virus, designated A, B and C. Characteristically, infection with one strain does not confer immunity against another. Also, the virus quickly produces new variants so that an attack of one is unlikely to provide protection against a later bout of the disease.

Complete rest is advised with plenty of fluid intake. Avoid solid food till the sense of taste returns.