Fever: A common symptom for most diseases

Why is homeothermy needed? •Therapeutic value of fever: •Diagnostic significance of fever: •Why some fevers are associated with chills & rigors? •Febrile conditions in pediatric age group: •Management of a fever:

Dr.Vivek Nalgirkar

9/30/2021 4 min read

Fever: A common symptom for most diseases

(Is it good or bad to have fever?)


Why is homeothermy needed?

Stable & normal temperature is a necessity for the enzymatic reactions of the cells. Optimal functioning of enzymes is possible only if the temperature is held constant in the milieu of cells and of the intracellular fluid.

This probably explains why the temperature-regulating system is one of the most efficient homeostatic systems of the body.

Humans have a shell temperature (which keeps changing with the ambient temperature) and a core temperature (which is always held constant within a narrow range). At the apex of this system is the hypothalamus, with its ‘thermostat’ and the ‘set point’.

So, the question that arises is this – “ Why do we suffer from fever in spite of having such an efficient regulatory mechanism?”

Another question that most people ask is – “Is it good or bad to have fever?”


·        Therapeutic value of fever:

Though not used any more, deliberate induction of fever has been used in the past as a treatment of certain illnesses. For instance, (i) Arthritic conditions:- It was known that in lower environmental temperatures (winter seasons), the joint pain conditions do exacerbate. Increasing the body temperature was shown to provide relief. (ii) Conditions such as syphilis:- The Treponema pallidum was shown to have reduced survival possibility with rise in temperature.

Injections of milk have been used to induce fever in such conditions.


·        Diagnostic significance of fever:

-         Fever is almost a definite indication of inflammation or infection somewhere in the body. It means the ongoing battle between the immune apparatus of the body and the invading pathogen.

Injury to cell membranes and release of PGs results in the formation of interleukins (IL-1) locally in hypothalamus. This raises the ‘set point’ of the hypothalamic thermostat, resulting in fever.

-         The pattern of fever and the associated symptoms (chills & rigor) provide clue to the diagnosis. Some common patterns are mentioned below ~

(i)                Low grade fevers (such as that in TB):- These fevers are known to typically appear in the evening. This is due to the diurnal rhythm of the steroid secretion. High levels of steroid in the morning hours will suppress the effects of inflammation (the PG-IL1 chain); hence no fever in the morning. However, as the steroid levels drop and are at their lowest in the evening, the fever begins to appear. In interesting and logical observation is that the people who have night shift works for prolonged durations, there is a ‘morning rise of temperature’ in case they have low-grade fever; the fever settles by evening. This is due to their inverted pattern of circadian rhythm and concurrent steroid levels.

(ii)              Step ladder pattern of typhoid fever; secondary/tertiary/quaternary fever patterns in malaria: Just by the pattern of fever and its appearance or absence, the diagnosis of the underlying disease is possible.

·        Why some fevers are associated with chills & rigors?

Chills & rigors are involuntary rhythmic shaking contractions of the body muscles. Such contractions generate heat, which appears paradoxical when there is already increased body temperature in fever. The explanation is based on the ‘set point’ of the hypothalamic thermostat. Normally, the set point is 98.6 degrees. In fever conditions, The PGs-ILs are formed locally in the milieu of the hypothalamic neurons. They raise the set point of the hypothalamic neurons at a higher level (say, 100 degrees). Now, this is the ‘new normal’, at least for the time being. If now, by some mechanism, body temperature decreases and reaches normal, it is considered a deviation from the new set point. Hypothalamus then sends signals via the lower centers to the body’s musculature, to induce shivering. It is an attempt to raise the body temperaure to the new set point. Of course, this is a temporary phenomenon, and as the disease condition improves, the set point reverts back to original normal (98.6 degrees).


·        Febrile conditions in pediatric age group:

Parents are often worried when their kids suffer from fever. The long-standing belief is – “Uncontrolled fevers damage the brain of the child”. This belief is further reinforced by the clinical condition called ‘febrile convulsions’. Parents therefore focus all their attention on reducing the fever. Functional development of brain continues to occur till the age of 6. Though fever, in general, does not impede the CNS development or functioning, very high grade fevers (causing the high temperatures in the milieu of neurons) should be treated vigilantly.

·        Management of a fever:

-         Record the body temperature at regular intervals; maintain a chart. It may provide clue to the diagnosis as also the pointers to prognosis (whether the condition is improving),

-         Maintain proper hydration; intake of fluids should be encouraged.

-         Paracetamol is the drug most commonly used to treat fever of any origin. It may be worth noting that paracetamol decreases the elevated body temperature; however, it does not act on a normal body temperature. That is, it does not further decrease an already normal body temperature. Thus, it may not work as a ‘preventive measure’.

-         Application of cold sponge to the forehead: It has a Physiological as well as emotional value. Physiologically, body will lose heat, by conduction, to the sponge. Temperature decreases locally, and then circulating blood carries heat from all over the body into that region, so that the heat is lost gradually and the body temperature is decreased.

Since heat is lost to the sponge by conduction, the sponge temperature will increase. Hence, the sponge should be removed every few minutes and soaked in cold water and placed back on forehead.

In summary, fever is a troublesome symptom and has to be managed diligently. However, two things should be understood clearly – (1) Fever is only a manifestation and not a disease in itself. Even as the fever is treated, the clinical condition must also be managed simultaneously. (2) However troublesome it may be, fever is actually a good sign. It is an indication that the body’s immune system is responding to the pathogen that’s caused the fever.



-         Dr. Vivek Nalgirkar