Dr. S. P. Srivastava*
Fever is as old as mankind and is the most common manifestation of disease. It has been observed that one fourth of children in hospital suffer from fever. Fever is the most common reason for a visit to the pediatrician or family physician. Besides causing discomfort to the patients it also causes anxiety to parents and unrealistic fear leading to unnecessary and inappropriate selection of drugs. Fever is often a sign of infection or illness. It is believed that fever helps the body to fight infection by stimulating natural defense mechanism.

What is Fever?:

  • Fever - When body's temperature is raised above its normal level
  • We can say fever if body temperature is:
    • Higher than 100.4oF (38ºC) rectally
    • Higher than 100ºF (37.8ºC) orally
    • Higher than 99ºF (37.2ºC) in arm pit
  • Similar to rectal temp - Aural temp
Core Temperature
The temperature of deep tissue of the body is the 'Core' which remains almost constant within ±1ºF day in and day out except when a person develops a febrile illness.

Skin Temperature
Skin temperature in contrast to core temperature rises and falls with the temperature of surroundings. This is the temperature that is important when we refer to the ability of the skin to lose heat to surrounding. The average normal temperature is generally considered to be between 98ºF and 98.6ºF (36.7ºC and 37ºC) when measured orally and approximately 1oF or 0.6ºF higher when measured rectally.

Temperature Regulation
Temperature of body is controlled by balancing heat production against heat lost. When the rate of heat production in the body is greater than the rate at which heat is being lost heat obviously builds up in the body and the body temperature rises. Conversely, when heat loss is greater, both body heat and body temperature decrease.

Heat Production
Heat is produced by:

  • Basal rate of metabolism
  • Extra rate of metabolism caused by muscular activity including muscle contraction caused by shivering
  • Extra metabolism caused by certain Hormone like Thyroxin
  • Extra metabolism caused by the effect of epinephrine, norepinephrine and sympathetic stimulation on cells
  • Body cell metabolism
A source of considerable heat particularly in 'New Born' is "Brown Fat". This fat has high rate of metabolism and its thermogenic function has been linked to that of an electric blanket.

How the set point is raised?
Set point is raised by endogenous and exogenous pyrogen. The term pyrogen is used to describe any substance which causes fever. Exogenous pyrogens are derived from out side the patients, most are microbial products, microbial toxins, or whole micro organism. Example of exogenous pyrogens is the Lipopolysaccharide Endotoxin produced by gram negative bacteria, Endotoxin by gram +ve bacteria. Exogenous pyrogens induce fever by stimulating cells of immune system like macrophages to release Interleukin IL1, IL6, Tumor necrosis Factors, ciliary neurotrophic factors. These immunological products convert Arachidonic Acid to Prostaglandine2 by isomer enzyme cyclo oxygenese 1, and cyclo oxygenese 2.

Effect of Elevated Temperature:
Serve the host defense by increasing chemotaxis, decreasing the microbial replication and improving lymphocyte function but at the cost of host in term of increase oxygen consumption and metabolic demand, protein catabolism and increase gluconeogenesis.

Characteristic of Febrile Condition Chill:
When the set point of hypothalamic temperature control center is suddenly changed from the normal level to higher than normal as result of tissue destruction, pyrogenic substance, dehydration body temperature usually takes time to new temperature set point. Whenever blood temperature is less than the set point of hypothalamic temperature, the usual response during the period is that the person experiences chill and feel extremely cold even though the body temperature remains already above normal. Skin is cold because of vasoconstriction and the person shivers. Chill continues till the body temperature reaches the hypothalamic raised set point. Then the person no longer feels either cold or hot; on the other hand there is 'crisis' when the set point is suddenly lowered.

Pyrexia of Unknown Origin:
  • Duration of Fever > 3 weeks
  • Failure to reach diagnosis despite 1 week of investigation
  • Temperature > 38.3ºC or 101oF on several occasion
New Classification:
  1. Classic PUO
  2. Nosocomial PUO
  3. Neutropenic PUO
  4. PUO Association with HIV
Types of Fever:

  • Continuous Temperature - never touches normal. Fluctuation Less Than 1ºC
  • Remittent - Fluctuation More than 2ºC
  • Intermittent - May Touch normal, Fever Daily - Quotidian, alternate Day - Tertian, Every two days - Quartan
  • Step ladder fever - Epstein Barr
Causes of Prolonged Fever:

  • Specific Fever - Typhoid, Meningococcal, Viral, Malaria, Kala azar, Tuberculosis, Filariasis, Leprosy, Amoebiasis
  • Pus anywhere in body
  • Infection and inflammatory condition - UTI, Tonsillitis, holecystitis, Pharyngitis, Pneumonia, Bronchopneumonia, Vasculitis, Pancreatitis, Infectious mononucleosis, sarcoidosis
  • Allergic - Pleural effusion, Asthma, Anaphylactoid purpura
  • Connective Tissue Disorder - Rheumatic, Rheumatoid, Polyarteritis, Scleroderma
  • Blood Diseases - Aplastic Anemia, Agranulocytosis, Leukemia, Hemolytic Anemia
  • Malignancy - Lymphoma, Carcinoma
  • Drug Reaction - Sulpha, Antibiotic, etc
Approach to Acute Onset of Pyrexia:
Cough, cold
Viral, Streptococcal, Diphtheria, OM
Respiratory Distress
Meningitis, Pneumonia, Bronchitis,
Diarrhea, Vomiting   
Shigella, Salmonella, Rotavirus, Polio, Appendicitis, meningitis,
Chills, Rigors 
Encephalitis, malaria, pus anywhere
Joint Pain   
Rheumatic, Rheumatoid

During days
TC, DC, Urine (R/E), Blood, Urine Culture
Urine (R/E), TC, DC, Widal, Urine Culture, X-ray chest
Above, all + ASO, bone marrow

Objective of Management of Fever:
  1. Bring Down Temperature
  2. Prevention of Effect of Fever

    • O2 Consumption
    • Metabolic demand
    • Protein Catabolism
    • Gluconeogenesis
  3. Prevention of Febrile Convulsion and effect of hyperpyrexia, Prevention of Dehydration
  4. To Increase Comfort, appetite, to decrease parents anxiety
  5. Treatment of underlying causes
How to Manage a Child with fever?
If a child is healthy and fever is not above 39ºC generally does not require treatment. Fever is brought down either by the administration of (a) antipyretic agents such as "Acetaminophen" (Paracetamol), Aspirin or other non-steroid anti-inflammatory agents like Ibuprofen, Nimesulide (b) by physical modalities like sponging or dabbing. Acetaminophen is currently the most frequently used antipyretic in children. While the relatively safety of acetaminophen has been well established over the past decades, there remains a significant risk for toxicity associated with excessive dose (> 80 mg/kg/day). The accepted acetaminophen dose for children is 15 mg/kg/dose 4-6 hourly as needed but should not receive not more than 5 doses. The total dose should not exceed 80 mg/kg/day. Pharmacists can also play role in assisting the parents as many cough and cold formula contain acetaminophen. Family members should be educated about dose and administration.

Aspirin - Aspirin is not given in children due to fear of Reye's syndrome.

Ibuprofen - In dose of 5-10 mg/kg may be beneficial. It is indicated 2nd line of drug. It has antipyretic, analgesic and anti inflammatory effect but it lead to abdominal discomfort, pain in abdomen and sometimes bleeding.
Nimesulide is sulfonamide compound and relatively weak inhibitor of prostaglandin and acts on both Cox1, and Cox2. It has adverse effect on gastrointestinal system, liver. Urticaria, purpura, renal impairment have been reported.

Treatment of Underlying Causes:
Most fevers are associated with self-limited infection like viral origin. When bacterial infection is documented, rational choice of antibiotics should be selected. Depending upon clinical evidence, laboratory investigation, epidemiological evidences and the site of infection starting from simple penicillin, ampicillin, Amoxicillin, cloxacillin, aminoglycoside, Quinolones and different generation of cephalosporins are needed. These days due to fear of Betalactamases problems, lactamase inhibitor combination are also being used.

Supportive Treatment:
Good nutrition, hydration is another area to be kept in mind. Children lose appetite during fever and become fussy also for food. One should select nutritious diet of palatable quality. Febrile children are likely to have dehydration so fluid and electrolyte balance should be maintained.
Fever is not a foe but it is friend. Parent should not be frightened or worry if child is having fever. It is not a disease but symptoms and also gives signal that some infection has been induced in body and body is fighting. To bring down temperature various antipyretic are available in market today. Best drug is Paracetamol which is in the use since decades. It has been recognized for safety and efficacy. Beside that full clinical examination, observation, history and physical examinations should be done to find out cause of fever and one should select appropriate and rational drug for proper management of fever.
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