MEDICAL MATTERS/DR MUIRIS HOUSTON:Do parents often overreact to a child's high temperature?
NO ONE likes the burning feeling associated with a high temperature. You feel generally unwell, a bit listless and you may have other symptoms associated with the (usually) infectious cause.
And we certainly worry about a child with an elevated temperature. Surveys show that parents are concerned that a severely feverish child might develop fits, brain damage or even death. Both parents and healthcare professionals spend a lot of time monitoring children's temperatures and attempting to reduce fevers as rapidly as possible.
But are we unnecessarily fixated on getting body temperature back to its normal range of 37.5 degrees Celsius plus or minus 0.5 degrees? Is it possible that a febrile response serves a therapeutic purpose and that interfering with it may be harmful? After all, that wise physician Hippocrates said: "Give me a fever and I can cure an illness."
Certainly, the evidence from research in animals is that a raised body temperature enhances immune-system activity. The high temperature creates a hostile environment for any invading bugs. It seems that the main infection fighting cells in the body, the white blood cells, multiply rapidly and work more effectively when the set-point of our internal thermostat is reset.
This is the difference between hyperthermia and fever: hyperthermia is an unregulated rise in core body temperature to a level above the thermostatic set point in the brain. Body temperature may rise to a dangerous extent in hyperthermia, for example in heat stroke, whereas the rise in temperature in fever stays within benign limits, rarely rising above 41.1 degrees Celsius.
While fever is most commonly caused by infection, it may also be triggered by cancer, tissue damage and the rejection of the body of a transplant or graft.
When doctors cannot figure out the exact cause of a fever, it is referred to as pyrexia of unknown origin (PUO). A 1961 study by infectious disease experts at Yale University found that about 35 per cent of PUO patients were eventually found to have infections; some 20 per cent had cancer and 15 per cent rheumatic diseases. A relatively high percentage remained undiagnosed, even with better diagnostic tools available today.
But should we be so fearful of fever? Probably not. The fever response seems to be ubiquitous among animals, helping them survive.
Certainly, in humans suppressing a fever seems to prolong the course of infections. Febrile pneumonia patients have a greater survival rate than those with normal temperatures. In the distant past, physicians deliberately caused a fever to treat people with syphilis.
Infectious disease specialists from Vanderbilt University have questioned "the pervasive application of antipyretics by physicians, nurses, pharmacists and patients".
And a review of childhood fever in the current issue of Drugs and Therapeutic Bulletin came to the following conclusion: "There is little evidence on the effects of antipyretic drug therapy on discomfort associated with fever and insufficient evidence on whether antipyretic
drugs help to prevent febrile seizures.
"However, a child who is distressed or uncomfortable because of the fever or associated symptoms, such as myalgia (muscle pain) or headache, is likely to benefit from treatment with paracetamol or ibuprofen."
Perhaps surprisingly, the review comes out against the use of tepid sponging, concluding it may cause the child discomfort and should be avoided. It suggests that doctors focus instead on making a diagnosis of the underlying cause rather than treating the high fever.
Finally, a word about taking your child's temperature.
The most reliable method is to use a rectal thermometer, but this is understandably disliked by patients and medical staff.
Plastic thermometer strips are more reliable when used in the mouth rather than on the forehead. But be wary of newer thermometers that work by detecting infrared heat emission from the ear drum. Their reliability has been found wanting in recent clinical trials: they have a tendency to underestimate temperatures by up to two degrees Celsius. (I am grateful to Dr Gary Stack, GP CME tutor for Co Kerry for bringing this to my attention.)
In 1896, Sir William Osler wrote: "Humanity has but three great enemies: fever, famine and war."
But by fever he meant infectious disease, a prescient reminder to focus on the cause, rather than the effect, of a fever.
• Dr Houston is pleased to hear from readers at mhouston@irish-times.ie but regrets he is unable to reply to individual medical queries