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Fever Without Source in Infants and Young Children

Two-thirds of children visit their physician with an acute febrile illness before the age of three. The most common causes of fever in children are respiratory, urinary tract, gastrointestinal, and central nervous system infections. Bacteremia may occur with any of these infections. Fever without a source that is related to a viral illness is often difficult to differentiate from occult bacteremia.

Clinical Evaluation of the Febrile Child

The child's health status, course of the current illness, birth and past medical history, and immunization status are evaluated.

Infants can be considered at low risk for serious bacterial infection if they had been healthy with no previous hospitalizations, were delivered at term and discharged home with their mother without complications, and had no previous antimicrobial therapy.

Physical Examination

Assessment of cardiopulmonary status includes a determination of vital signs. Children who are toxic require immediate cardiovascular stabilization and a complete sepsis evaluation, with empiric antimicrobial therapy.

Fever is usually defined as a rectal temperature of at least 38.0°C (100.4°F). Axillary and tympanic measurements are unreliable. Serious infections can also occur in afebrile or hypothermic infants. Fever may also be related to vaccine reactions.

Over bundling of small infants can cause temperature elevations. When this is suspected, the temperature should be rechecked with the child unbundled for 15 minutes.

If no focal bacterial infection (eg, skin, soft tissue infection, otitis media) is apparent, the child is at low risk for serious bacterial infection.

Children with clinical signs of a serious illness or sepsis (lethargy, signs of poor perfusion, marked hypoventilation or hyperventilation, or cyanosis) are considered to be toxic.

The quality of cry, reaction to parents, color, state of hydration, response to social overtures, affect, respiratory status and effort, and peripheral perfusion should be assessed.

Neonates with acute bacterial meningitis often lack meningismus. Meningitis in neonates may manifest as temperature instability (hyperthermia or hypothermia), poor feeding, listlessness, lethargy, irritability, vomiting, or respiratory distress. A bulging fontanelle may be seen in up to one-third of cases, although it usually appears later in the course of illness. The most common CNS signs in the newborn are lethargy and irritability.