Definition

Influenza is a highly infectious disease that affects the respiratory (breathing) tract. It is also known as the flu or grippe. The disease is caused by a virus. When inhaled, the virus attacks cells in the upper part of the respiratory system and causes symptoms such as fatigue, fever and chills, a hacking cough, and body aches. Influenza can also lead to other, more serious infections.

The disease known as stomach flu is not really a form of influenza. The influenza virus normally does not attack the stomach or intestines. Stomach flu is instead caused by other organisms, such as the salmonella or E. coli bacteria.

Description

The flu is often confused with the common cold (see common cold entry), but it is actually much more serious. The annual death toll due to influenza and its complications averages twenty thousand in the United States alone. Sometimes, a...