FEVER IN A CHILD

Fever in a Child

is the most common chief complaint presenting to an emergency department and accounts for 30% of outpatient visits each year. Early studies suggested that infants younger than 3 months were at high risk of a serious bacterial illness (SBI), which included sepsis, pyelonephritis, pneumonia, and meningitis. Current practice guidelines vary in their cut-offs for evaluation and treatment strategies. Neonates are clearly at the highest risk, while infants in their second and third months of life gradually transition to the lower risk profile of older infants and children. The incidence of bacteremia falls from around 10% among febrile neonates to approximately 0.2% in immunized infants and children older than 4 months; meningitis risk decreases from about 1% in the first month of life to < 0.1% later in infancy; the risk for pyelonephritis remains relatively constant among young girls with fever, and gradually decreases among boys over the first year of life. The individual practitioner must weigh these risks against the invasiveness of their ED evaluation and make shared decisions with the family on the best approach.

CLINICAL FEATURES:

In the neonate or infant < 2 to 3 months of age, the threshold for concerning fever is 38°C (100.4°F); in infants and children 3 to 36 months old, the threshold is 39°C (102.2°F). In general, higher temperatures are associated with a higher incidence of serious bacterial illness.

Young infants are especially problematic in assessing severity of illness. Immature development and immature immunity make reliable examination findings difficult. Persistent crying, inability to console, poor feeding, or temperature instability may be the only findings suggestive of an SBI.

DIFFERENTIAL DIAGNOSIS

Infants up to 3 Months

History and physical examination are rarely helpful in diagnosing or excluding SBI in this age group as symptoms are typically vague, and physical exam findings are unreliable: meningismus is present in <15% of bacterial meningitis; rales may not be appreciated in the absence of ability to generate negative inspiratory forces; and bacteremia can occur in the well-appearing infant. A history of cough, tachypnea, or hypoxia (by pulse oximetry), however, should alert the examiner to a possible lower respiratory tract infection and prompt chest radiograph.

The safest course for 0 to 28 day old infants is full sepsis testing, admission, and empiric antibiotic treatment. Antibiotic coverage in this age group includes ampicillin for Listeria monocytogenes . Sepsis testing includes complete blood count (CBC), blood culture, urinalysis and urine culture, chest radiograph, and lumbar puncture.

Criteria used to define infants at low risk for SBI in the 31 to 90 days age group include well appearance without a history of prematurity or other comorbidity, and a normal urinalysis. Infants with a suggestion of lower respiratory tract disease should have a chest radiograph. The Boston and, Philadelphia, criteria (which include normal CSF and CBC) should only be applied if the child's presentation warrants the sepsis testing listed above. Obtaining these laboratory tests is no longer considered routine for infants in the 31 to 90 days age group because of the lower incidence of bacteremia since the advent of the Hib (Haemophilus influenzae type B) and Prevnar (Streptococcus pneumoniae) vaccinations.

All ill appearing infants should receive parenteral antibiotic therapy and be admitted to the hospital. Management of low-risk infants remains a subject of significant debate. Infants older than 28 days at low risk may be managed conservatively as inpatients with ceftriaxone pending cultures; as inpatients without antibiotics; as outpatients with ceftriaxone 50 milligrams/kilogram IM; or as outpatients without antibiotics. The key deciding factor should be the physician's comfort level and the ability for close follow-up, typically within 12 hours. If antibiotics are administered (inpatient or outpatient), CSF and blood cultures should be obtained prior to administration of antibiotics.

Well appearing febrile children between the ages of 29 and 90 days with an identifiable viral source of infection (eg, respiratory syncytial virus [RSV] or influenza) should have urinary tract infection (UTI) ruled out before being discharged from the emergency department. Chest radiographs should be obtained at the discretion of the clinician, but are not indicated for infants with RSV. Lumbar puncture in this group of children may be deferred in those who are well appearing and test positive for a viral source of infection.

Infants 3 to 36 Months

Physical examination findings become more reliable with increasing age, though meningeal signs remain unreliable throughout the first year of life. Viral illnesses including pneumonia account for most febrile illnesses in this age group; patients with clinical findings suggesting pneumonia should have a chest radiograph. One infection that may present with fever only in this age group is UTI. UTI is a significant source of bacterial illness in females prior to toilet training, circumcised boys younger than 6 months of age and uncircumcised boys under 1 year of age; these patients should have urinalysis and urine culture (by catheterization) if a source for the fever is not otherwise identified.

Older Febrile Children

The risk for bacteremia in children older than 3 years is < 0.2% since the introduction of Prevnar. CBC and blood cultures are no longer recommended in immunized older children with fever. Etiologies to consider in older febrile children include streptococcal pharyngitis, pneumonia, and EBV infection. Testing is directed by clinical presentation

TREATMENT STRATEGY:

Although fever makes children uncomfortable and may potentiate seizures, it typically is not harmful to children, though it does lower the seizure threshold. The physician can use several methods to reduce fever:

Remove excessive clothing and blankets to increase heat loss through radiation.

Administer acetaminophen 15 milligrams/kilogram PO/PR every 4 to 6 hours (maximum dose, 80 milligrams/kilogram in 24 hours).

Consider ibuprofen 10 milligrams/kilogram PO in children older than 1 year of age; the dose can be repeated every 6 to 8 hours (maximum of 40 milligrams/kilogram in 24 hours), and can be given concurrently with acetaminophen.

The disposition of young infants is discussed above. Patients who are called to return to the ED for evaluation of positive blood cultures require repeat evaluation. Patients with cultures positive forNeisseria meningitidis or methicillin-resistant Staphylococcus aureus, should be hospitalized and treated with parenteral antibiotics. Otherwise, well appearing afebrile children already on antibiotics should complete the course of therapy. If the patient is afebrile, clinically well, without a focus of infection, and not currently on antibiotics, controversy exists as to the need for repeat cultures and antibiotics; in general, neither repeat testing or treatment is necessary. If the child with a positive blood culture remains febrile or continues to appear ill, a full septic workup (complete blood cell count, repeat blood culture, lumbar puncture, urinalysis, urine culture, and chest radiograph) should be performed. The patient should be hospitalized and receive parenteral antibiotics