FEVER - Full extract 

Despite varying environmental conditions and different levels of physical activity, the body's temperature is kept in a fairly narrow range--about 35.8 C to 37.2 C. Interestingly, there is a slight diurnal fluctuation of body temperature from a lower figure in the early morning hours to a marginally higher figure in the evening. In practical terms, if the body temperature rises above 37.2 C the person is considered to have a fever.

Normal control of body temperature depends on a sophisticated feedback system and a thermostat situated in a part of the brain called the hypothalamus. If the temperature gets too high, sensors in the hypothalamus detect this and trigger a change in the distribution of bloodflow. Blood is diverted to the skin causing flushing and radiation of heat. Sweating also occurs and the subsequent evaporation from the skin reduces body temperature further. The reverse occurs when the body temperature gets too low; blood is diverted away from the skin turning it into an insulating layer. Shivering occurs, heat is produced and the body temperature rises.

It is worthwhile having a reliable thermometer in the house. Taking the temperature is so easy and it gives a great deal of information. The actual temperature is much more helpful than a hunch that someone "feels a bit hot". Thermometers vary in price from $3 for the standard mercury type up to about $15 for the newer digital read-out variety.

The standard mercury thermometer should be stored in a cool cupboard and the column checked to see that it is below the normal arrow before it is used. Oral, arm-pit, vaginal or rectal temperatures can be measured. The oral temperature is most commonly used, except in young infants where for safety reasons arm-pit temperatures are preferred. A trained nurse or doctor may take a rectal temperature in some situations. The latest infra-red thermometers have a tiny probe that fits into the ear and gives a very accurate reading within seconds.

Although a fever nearly always indicates infection, it does not necessarily mean that the person has a serious illness. Fever is one way the body copes with infection; viruses are more susceptible to the body's immune system in the presence of a fever. However, if the person is feeling very sick or there are symptoms like a sore ear or coughing, it is important to see the doctor to check that no bacterial infection is present. Unlike viral infections, those caused by bacteria often need antibiotic treatment.

A fever that occurs with abdominal pain, urinary symptoms, breathing difficulties, unusual rashes, neck pain or sensitivity to light, always requires urgent medical assessment. Less commonly, fevers may also be present with the tissue damage from a heart attack, side-effects of certain medications, and with immune disorders like rheumatoid disease. Rarely, it can be associated with cancer and certain blood disorders.

Fevers are best managed with rest, extra fluids and wearing light clothing. Paracetamol is suitable for any associated pain. Some young children can become delirious or have a febrile convulsion if the temperature becomes too high. Although rather scary, these convulsions do not cause any permanent damage and are not associated with other conditions like epilepsy. Anyone with a fever lasting more than 48 hours should see the doctor, as should anyone whose condition appears to be worsening.

A careful history and examination by the doctor is usually enough to identify the cause of the fever. Things like recent overseas travel, occupation, exposure to animals, medications taken, and any associated symptoms should all be considered. The examination involves a detailed search for evidence of infection, not just the usual upper respiratory infections but less obvious causes like meningitis and urinary tract infections. In patients who are more ill various blood tests and X-rays may be required. Sometimes referral to a specialist may also be necessary. Antibiotics are usually not prescribed unless a proven bacterial infection can be demonstrated.

Health tips:
 * A fever does not necessarily mean a serious illness. Often it will settle without specific treatment.

* If the fever persists, or if there is doubt about its cause, it is better to see your doctor for advice.

Dr. Andrew Pattison: Common Consultations
North East Valley Division General Practice, Melbourne, Australia.   Disclaimer
  - Last modified: August 18, 2001