Fever in Infancy and Childhood
Fever is defined as the elevation of body temperature above normal. Normal core body temperature is 37°C (98.6°F) ± 1°C, whereas a temperature of 38°C (100.4°F) or higher represents a fever.
Rectal temperature most accurately reflects core temperature, especially in infants. Oral or tympanic temperatures are suitable for older children but can be inaccurate.
Fever in children is usually the result of an underlying infection but occasionally is due to collagen vascular disease, malignancy, or metabolic disorder, such as hyperthyroidism.
Excessive environmental temperature also produce fever.
Febrile children may be sleepier than usual. Respiratory symptoms include rhinorrhea, sore throat, otalgia, and cough.
Vomiting and diarrhea occur in gastrointestinal infections as well as other illnesses. Dysuria and frequent urination are suggestive of urinary tract infection (UTI) in older children but are often absent in infants.
Pronounced lethargy or irritability is a red flag for a serious bacterial illness (SBI).
Observation of the older infant or child is very helpful in determining the index of suspicion for an SBI. A pink, alert, wellhydrated, smiling, or easily consoled infant is much less likely to have an SBI than a pale, lethargic, dehydrated, dull, or irritable child.
Screening laboratory tests.
No test can detect every SBI in all febrile children, but the following values in infants older than 28 days deserve further investigation:
Specific diagnostic studies
- White blood cell (WBC) count of 15,000/µL or more or WBC count of less than 5,000/µL
Absolute band count of 1,500/µL or higher
- Presence of toxic granulation or vacuolization in neutrophils
is indicated in the presence of pulmonary symptoms, such as tachypnea. Rales are not always heard in young children with pneumonia.
with culture should be considered in male infants younger than 6 months of age, older uncircumcised male infants, and female infants younger than 2 years old when fever does not have a source.
should be considered in the child younger than 36 months who is at high risk for SBI, as indicated by physical examination, fever of 39°C or higher, or WBC count of 15,000/µL or greater.
should be performed in the presence of symptoms or signs suggestive of meningitis, such as excessive irritability or lethargy, seizures, or bulging fontanelle.
of bloody or mucoid diarrhea demonstrating five or more WBCs per high-power field (hpf) suggests bacterial enteritis warranting stool culture for Salmonella, Shigella, Campylobacter, Yersinia, or pathogenic Escherichia coli.