Why do people get fever??

To really understand what a fever is, you need to say hello to the hypothalamus. The hypothalamus is in the center of your brain. Think of it as your body's thermostat — like that thing on the wall in your house that you use to set the heat or the air conditioning. Your hypothalamus knows what temperature your body should be and will send messages to your body to keep it that way.

Once these germs march in and make you sick, they can sometimes cause certain chemicals to flow into your blood. When your hypothalamus gets word that these chemicals are on the scene, it automatically sets your body's thermostat higher. Instead of saying your body should be 98.6° F (37° C), your body's thermostat might say that it should be 102° F (38.9° C).

Why does the hypothalamus tell your body to change to a new temperature? Researchers believe turning up the heat is the body's way of fighting the germs and making your body a less comfortable place for them. A fever is also a good signal to you, your parents, and your doctor that you are sick. Without fever, it's much more difficult to tell if a person has an infection. That's why grown-ups are concerned when you have a fever.



from: http://kidshealth.org