Infectious Diseases

FEVER: What is it really?

Fever! It happens to everybody sometime in their lives. Fever alarms us because it means there is something occurring in our bodies that abnormal. We’re sick! When fever occurs in children, especially infants, fear grips us. We think the worst; that’s just human nature. Babies and small children show the effects of fever so starkly and alarmingly. They become lethargic, refuse to eat, are listless, and fold into a ball of inactive bone and muscle. You feel so sorry for them because you know had bad they feel.

The fancy term for fever is PYREXIA, though I’ve never heard any doctor say that even in a case presentation. But you know Medicine—use a complicated term for something everyone knows in simple language. Hyperpyrexia is an analogous term meaning excessive heat. That’s another infrequently used term. The normal body temperature in Fahrenheit is 98.6°. In Celsius or Centigrade, normal is 37°. I have often heard people claim their normal temperature is 97° and they’re probably right.

To determine the “normal” temperature of humans, scientists sampled the oral temperatures of many thousands of people taken under exactly the same circumstances. These results were then plotted on a “bell-shaped curve” to determine a range of normal. The area where the majority of the temperatures fell on the graph allowed researchers to established high normal and low normal temperatures. This became the “normal temperature range” of 97.6°F to 99.6°F. The mathematical mean temperature in the middle of the range was then considered the average normal temp, or 98.6°. So, if your usual temp is 97°, your normal is lower than the overall normal of 98.6°.

Fever in adults is defined medically as a temperature of 100.4°F or higher. A lot of folks with low normal temps claim they have “a fever” at lower than accepted temperature levels. If you’re one of those folks, it is true only to the extent that you are also ill when that “fever” is recorded. Having a temp of 99.6° is not a fever if you’re not also feeling ill.

Fever is a symptom or signs the body expresses when it has been “invaded” by some outside organism such as a bacterium, virus, or fungus, or its metabolic rate has been accelerated by a serious change in an organ system such as would occur if one received a blood transfusion, had an auto-immune disorder like rheumatoid arthritis, or had hidden cancer (occult malignancy).

The body’s temperature is controlled by the Hypothamalmus, a small section of the brain located deep inside the skull situated just above the pituitary gland and below the thalamus. The hypothalamus controls several bodily functions over which we have no conscious control, fever being one of those.

Our body’s response to organisms that are trying to cause illness is to produce increased numbers of White Blood Cells (WBC’s) in our blood. WBC’s circulate through the bloodstream and congregate in large numbers near the site of the invading organism to fight against the problems it is causing. As blood flows through the hypothalamus, the increase in WBC’s is sensed, and as a protective automatic response, the body temperature is elevated. Elevated body temperature speeds up metabolism and accelerates ingestion and removal of unwanted organisms.

Fever is, thus, a mechanism the body uses to protect itself, but it has profound effects and symptoms that make us feel bad. Cold, clammy, pale, and sweaty skin occurs as surface vessels close down and force blood into the central organs to protect them. Shivers develop in the muscles when blood is shunted to the central body areas and away from the muscles. Headache, weakness, listlessness, drowsiness, loss of appetite, loss of strength, hallucinations, and decreasing level of consciousness occur as the infection worsens. Seizures, coma, and death are the eventual outcomes of an overwhelming infection that treatment has failed to resolve.

Normal temperature varies by age!

The American Academy of Pediatrics, the pediatrician’s organization, says infants less than three months who have a temp over 100.4° should see a doctor. That’s a much lower threshold than one would have for an adult, but infants can quickly become very ill and require medical attention.

Children ages 3-6 months should see a doctor for a temp of 102° or more.

The normal adult temperature is 98.6° F. One’s temp is lowest in the early morning hours. One’s temp is the highest in mid-afternoon and evening. That’s why children always get sicker around their bedtime or yours.

Adults should worry when their temp gets above 102° and especially if it reaches 103°.

The excess heat produced by the hypothalamus escapes from the body through the skin as radiant energy and also through the evaporation of water in perspiration.

Causes of fever are numerous! Bacteria, viruses, fungi, drug reactions, blood transfusion reactions to the white blood cells in whole blood (transfusions of concentrated (packed) red blood cells with WBC’s removed are preferred). The big dilemma for doctors is the fever for which no cause can be found. It’s termed an “FUO,” Fever of Undetermined Origin. If after a urinalysis, urine culture, CBC (blood count), chest X-ray, fecal culture, blood culture, and culture of a suspected site of infection fail to show a cause, the patient officially has an FUO. This starts in motion a series of tests and investigations looking for an “occult (hidden) malignancy.” Cancer is unfortunately an all-too-common cause of unexplained fever. And for some also unexplained reason, once the cancer is diagnosed, the mysterious fever disappears.

The symptoms with which a patient presents also guide physicians in their attempt to find the cause of fever. Rash, respiratory symptoms, urinary symptoms, stiff neck, headache, localized chest or abdominal pain, shortness of breath, and delirium/confusion all provide clues where to look.

Fever itself is treated with “antipyretic” drugs like ibuprofen, acetaminophen, and now less frequently, aspirin. Oral fluids, “tepid” baths, thin, lightweight clothing, cooling blankets, and rest are also helpful. Cause-specific treatment is obviously indicated when the cause is determined. Bacterial infections usually respond to “broad-spectrum” antibiotics—those drugs that kill a wide range of organisms. Viral infections respond to antivirals like acyclovir and fungi to antifungals like amphotericin and fluconazole.

Aspirin is used infrequently, now, because of the potential for gastrointestinal bleeding, other bleeding tendencies, and Reye’s Syndrome, a rare but lethal swelling of the brain and liver in children treated with aspirin for the fever of the flu or chickenpox. Aspirin to treat fever is used only in rare situations. Acetaminophen and ibuprofen are safer and just as effective.

I guess one could say fever is a necessary evil. But when you look at it as a significant indicator of problems in your body (that red light that comes on in an emergency), it alerts us to the need to find the cause and begin proper treatment to return us to our usual healthy state.

Dr. G’s Opinion: I feel strongly that people who say they have a fever with a temp of less than 100°F because their “normal temperature is 97.6°F” are incorrect unless they are also ill at that time with specific symptoms. For some reason, they want that temperature to be indicative of a problem when it may not be. But nothing worries a parent more than their infant or toddler with a temperature of 104°F. As mentioned previously, it’s natural to think they have meningitis, pneumonia, or some other potentially catastrophic disease.

One of the most anxiety-provoking childhood illnesses is Roseola infantum. Roseola is a viral illness characterized by 2-4 days of fever, as high as 105°F for which a cause is not found. The child is ill but not to the degree one would expect that high a fever. Suddenly, the diagnosis becomes obvious when the fever breaks (stops) and the child breaks out with a faint, measles-like rash characteristic of Roseola. The fever never reoccurs, and the rash is gone in 3-5 days. I saw a case of Roseola 2 or 3 times a year, always in infants under age 3 years, always with a high temperature over 103°F, and always with the classic progression of high fever followed by a rash followed by cessation of the fever. If the doctor can suppress the urge to treat the fever with antibiotics instead of antipyretics, the uncertainty of whether the rash is a reaction to the antibiotic is avoided. Never prescribe an antibiotic for fever unless you know the cause of the infection you’re treating. Fever is a symptom, not a disease, and is a warning sign that you need to start looking for the cause.


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