Resource: Function of Fever

When a loved one becomes feverish and starts to shiver and sweat, our first thought is to get their temperature down. Pharmacies sell billions of fever-reducing pills like aspirin and acetaminophen every year, and schools often insist that students stay home until their fever is gone. But is this "fever phobia" backed up by science? Increasingly, medical researchers are discovering that fever has endured in mammals and other creatures for good reasons, though the reasons why are not yet clear. Often, a fever is actually a reflection of the body's defenses going into high gear in response to an infection. Some parts of the immune system work better at a higher temperature. Fever raises the body's temperature, which strengthens its resistance to infection and increases the odds of survival. Most of the time, fever isn't dangerous in and of itself. In fact, the new thinking is that mild fever can be a positive adaptation and shouldn't necessarily be treated. In some instances, though, fever may spur the microbes' growth rate by raising the temperature of the host body. In this case, the attackers have evolved a way to chemically manipulate the host's immune system for their own advantage. And a high fever is a danger sign, especially in young children. What is this mysterious phenomenon we call fever? It's not simply a rise in body temperature. It is an upward shift in the body's "set point," or core temperature, which is regulated by the hypothalamus in the brain. In response to an infection, the body releases chemicals that create the sensation of being cold. The hypothalamus then raises the set point by making the body burn fat, reduce blood flow to the skin, and shiver. In a dramatic demonstration of fever's benefits, researcher Matthew Kluger infected desert iguanas with bacteria. Because these lizards are cold-blooded, they must use heat sources outside their bodies -- in this case, sun lamps -- to fight infections. All except one of the 13 iguanas sought the warmth to raise their temperatures, and those 12 survived; the one that didn't died. Next, Kluger injected 12 other iguanas with live bacteria, and also gave them a drug that kept their body temperatures down even when they sought the warmth of the heat lamps. Five of these lizards failed to develop a fever, and died as a result. The other seven, which somehow became feverish despite the drug, survived. Despite experiments like this, scientists haven't yet answered all their questions about this common and ancient body symptom.

How do you think an organism and its cells would be helped by a warm temperature?

How is fever different from a simple rise in body temperature?

Why would the lizards need an outside heat source?