Eilleen Ratajczak, age 11, of Tucson, Ariz., for her question:

WHAT CAUSES A FEVER?

The human body, a very complex structure, continuously adjusts to the exertions placed upon it. Many of its most remarkable accomplishments happen without our knowledge  such as a fever. When the body tissues are attacked by a sneaky bacterial infection or virus of some sort, a fever occurs to indicate that the body is trying to fight off the pesky invaders.

A fever generally means that the sweat glands are closed off, and the tiny blood vessels near the skin are contracted. This sends more blood to the interior of the body, which brings more white cells on the march to fight the infection. With the rise in body temperature, many bacteria are killed. In an infectious disease, fever usually spreads throughout the body. But many times, such as in the case of an infected cut on the finger, the tissues surrounding the cut are feverish, but not the entire body. Doctors can tell a lot about the specific nature of a disease just by calculating the fever's frequency and severity.