Fever, Pediatric



  • Fever is defined as a temperature of 38°C (100.4°F) rectally:
    • Oral and tympanic temperatures are generally 0.6–1°C lower
  • Tympanic temperatures are not accurate in children younger than 6 mo. When measuring pull posteriorly and superiorly on the external ear at the midpoint between the apex of the helix and inferior border of the lobule
  • Axillary temperatures are unreliable
  • Children who are afebrile but have a reliable history of measured fever should be considered to be febrile to the degree reported
  • Accounts for up to 20% of children presenting to the ED. Challenge is to identify those with significant underlying infections


  • General:
    • Bacteremia
    • Infants ≤90 d: E. coli and group B streptococcus
    • Older infants: Streptococcus pneumoniae. Haemophilus influenzae type B less common with widespread immunizations
    • Viral illness, often accompanied by exanthem (varicella, roseola, rubella), coxsackievirus (hand-foot-and-mouth disease)
    • H. influenzae type B and S. pneumoniae vaccines have reduced incidence of Haemophilus and pneumococcal disease
  • CNS: Meningitis, encephalitis
  • Head, eyes, ears, neck, and throat (HEENT): Otitis media, facial cellulitis, orbital/periorbital cellulitis, pharyngitis (group A β-hemolytic streptococcus, herpangina, adenovirus pharyngoconjunctival fever), viral gingivostomatitis (herpes and coxsackievirus), cervical adenitis, sinusitis, mastoiditis, conjunctivitis, peritonsillar/retropharyngeal abscess
  • Respiratory: Croup (paramyxovirus), epiglottitis, bronchiolitis (respiratory syncytial virus [RSV]), pneumonia, empyema, influenza
  • Cardiovascular: Purulent pericarditis, endocarditis, myocarditis
  • Genitourinary (GU): Cystitis, pyelonephritis
  • GI: Bacterial/viral gastroenteritis, intussusception, appendicitis, hepatitis
  • Extremity: Osteomyelitis, septic arthritis, abscess, cellulitis
  • Miscellaneous: Herpes simplex virus infection in the neonate, Kawasaki disease, vaccine (DPT) reaction, heat exhaustion/stroke, factitious, familial dysautonomia, thyrotoxicosis, collagen vascular disease, vasculitis, rheumatic fever, malignancy, drug induced, overbundling (uncommon, recheck 15 min after unbundling)
  • Occult bacteremia occurs in association with a host of clinical entities. The group at highest risk are those ≤24 mo with a fever of ≥39.4°C and a WBC of 15,000 cell/mm3
  • Hyperpyrexia (temp >41°C (105.8°F) commonly associated with serious infection. Temperatures >42°C often have a noninfectious cause such as hyperthermia, head injury, drug ingestion, malignant hyperthermia

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