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When to worry about (or ignore) a fever

When to worry about (or ignore) a fever

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Michael Huckabee is professor and director of the physician assistant program at UNMC. He's worked as a physician assistant for 30 years, primarily in rural Nebraska. He blogs every other Monday. Click here to read more from Michael Huckabee.

We break into all kinds of fevers this time of year: cabin, Spring, mall and Husker, among them. So how do we know when to be concerned?

Humans run a body temperature usually between 97 and 99 degrees F. Body temps run up and down throughout the day as a part of our normal circadium rhythms. Typically they're lowest about two hours before we wake up, and reach a peak sometime in the evening. Clinicians recommend watching the temperature much more closely in infants. Anything over 99 degrees in a baby under eight-weeks-old deserves attention. In most otherwise healthy kids we won't call it much of a fever until over 100, and in adults it doesn't get much attention until over 101.

A study in Nigeria looked at 182 children reporting to an emergency ward and asked the caregiver, the nurse and the doctor to each feel for a fever, typically preferring to feel the forehead with the back of the hand. Then temperatures were taken with a thermometer. The caregivers (often family members) were best at determining a fever, though not statistically significantly better than doctors or nurses. Clinicians missed a fever in about one in 15 kids with the thermometer reading over 100.4 degrees.

Rectal thermometers remain the most accurate, but the under-the-tongue method is often preferred for convenience. Tympanic (ear) thermometers are the next choice for accuracy. Skin temperature devices, often sold as infrared or disposable skin sensors, may not always give an accurate measure because the skin surface often works to cool the body (by sweating and dilating superficial blood vessels).

If the fever isn't uncomfortable, it usually won't require treatment. An accompanying headache, body aches, weakness or thirst all deserve a response – but a fever alone is probably OK. Parents are often concerned that if a fever gets too high, a febrile seizure may occur. While it's a worthwhile concern, these types of seizures are more likely to occur when the body temperature is raised or lowered quickly, not because a fever is too high.

A fever creates an environment that inhibits bacterial and viral growth. An even better reason for allowing a fever is because there are specific immune system blood cells, among them CD8+ cytotoxic T-cells, that can destroy infected cells and even some tumor cells. A mild fever will stimulate these to fight the infection. While this is most clearly documented in mice, most researchers suggest the same is true in humans.

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