Ira Shah
Consultant Pediatrician, B.J.Wadia Hospital for Children, Mumbai, India
First Created: 02/28/2001 

Normal Body Temperature

The hypothalamus is the heat-regulating center of the body and helps in maintaining stable body temperature. The normal body temperature ranges from 37.0 degrees C and 37.5 degrees C with evening temperatures being 0.5-1.0 degrees C higher than in the morning. Oral temperature is about 0.4 degrees C below as compared to rectal temperature and the axillary temperature is about 1 degree C below rectal temperature.


Persistent elevation of body temperature above the normal levels in an individual.

Pathogenesis of Fever

Due to infection, inflammation, or immunologic reaction, there is a release of endogenous pyrogens by phagocytic cells. The pyrogen acts on the thermoregulatory center increasing heat generation. Prostaglandins released to act on the vasomotor center and prevent heat loss. Thus body temperature rises.

Type of Fever

Intermittent fever - Fever that touches normally for a few hours during the day. It is seen in malaria, acute pyelonephritis, local boils, and furuncles.

Remittent fever - Fever that fluctuates between 1.5 degrees F in 24 hours without touching normal.

Continuous fever - Fever that does not touch normal and fluctuates less than 1.5 degrees F in a day. It is seen in enteric fever, Bacterial endocarditis, viral pneumonia.

Characteristic Features of Different Types of Fever

Certain characteristic features of different types of fever:

  • Fever with rigors or chills: Malaria, pneumonia (lobar), pyelonephritis, bacterial endocarditis, abscess, cholangitis.
  • Step ladder fever: enteric fever
  • Relapsing or periodic fever: (Fever occurring in bouts lasting for days with afebrile phases) - Brucellosis, Hodgkin's disease
  • Sudden onset fever: Pyelonephritis, Pneumonia
  • Gradual onset fever: Typhoid, infective endocarditis, TB, Brucellosis.
  • Double rise of fever: Kala-azar, malaria, liver abscess, typhoid, UTI

Common Causes of Fever In Children

  • Infections
    • Bacterial
    • Viral
    • Spirochaetal
    • Protozoal
    • Fungal
    • Ricketssial

  • Neoplasms
  • Allergic reactions
  • Collagen disorders
  • Drugs
  • Granulomatous disorders or sarcoidosis
  • Heat stroke
  • Factitious fever

Note: Fever in an infant less than 3 mo of age should be considered as bacterial until proved otherwise.

Pyrexia Of Unknown Origin (PUO)

Fever lasting for at least 10 days with no apparent diagnosis after investigations.

Approach to a Child With Fever

Associated signs and symptoms:

  • Cough, cold, breathlessness: URTI, bronchitis, pneumonia, empyema, sinusitis, lung abscess, otitis media, pharyngitis
  • Vomiting, pain in abdomen: Hepatitis, appendicitis, enteric fever, amoebas
  • Post-tussive vomiting: Pertussis
  • Projectile vomiting: Meningitis
  • Jaundice: hepatitis
  • Splenomegaly: malaria, kala-azar, infectious mononucleosis, lymphoma, enteric fever, bacterial endocarditis
  • Headache: sinusitis, otitis media, meningitis
  • Skin rash: measles, chickenpox, rubella, meningococcemia, fifth disease, rickettsia
  • Joint swelling: septic arthritis
  • Lymphadenopathy: tuberculosis, toxoplasmosis, Infectious mononucleosis, Brucellosis, HIV, lymphoma
  • Conjunctivitis: Bulbar conjunctivitis-Kawasaki's disease, leptospirosis; Palpebral conjunctivitis-measles, infectious mononucleosis

Investigations In Pyrexia Of Unknown Origin


  • CBC and peripheral smear examination with ESR
  • Urine examination
  • Stool examination
  • X-Ray chest

Additional tests (as indicated)

  • Blood culture
  • Widal test
  • Liver function tests
  • Serological tests to antibodies such as for Hepatitis virus, EBV, CMV, Brucellosis, HIV etc.
  • Paul Bunnel test for infection mononucleosis
  • Mantoux test
  • Sputum examination
  • Auto antibody tests such as RA factor, ANA, dsDNA.
  • USG Abdomen
  • Biopsy of affected organ -liver, lymph nodes, bone marrow
  • Total body CT or MRI scanning

Treatment of Fever

For fever less than 100 degree F, tepid sponging to bring down the fever is recommended. Antipyretics are recommended for fever >100 degree F or for fevers not coming to normal.

  • Acetaminophen Acetaminophen (10 mg/kg/dose PO/PR/IV every 6-8 hourly)
  • Non-steroidal anti-inflammatory agents such as Ibuprofen (5-10 mg/kg/dose PO every 6-8 hourly) are useful.

Fever Fever https://www.pediatriconcall.com/show_article/default.aspx?main_cat=alternative-medicine&sub_cat=fever&url=fever-introduction 2001-02-28
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