7/28/2019 Fever Without a Source

1/2

FEVER WITHOUT A SOURCE

DEFINITION: As the title implies, fever without a source is a fever without an identifiable cause on history

or physical exam. Fever is defined as >100.4 or 38.0. Because the implications of fever without a source

are different for different age groups the epidemiology, presentation, differential, work up and treatment

will depend on the age of the child at presentation.

EPIDEMIOLOGY: 5-10% of all children presenting with fever have no source.

Birth - 2 months

EPIDEMIOLOGY/DIFFERENTIAL Many infants with a fever will have a viral infection. However, the

risk of serious bacterial infection (SBI) is greatest in this age group. Bacterial illness includes sepsis,

meningitis, urinary tract infections (UTI), enteritis, osteomyelitis, and suppurative arthritis. Other possible

infections include otitis media, pneumonia, omphalitis, mastitis and skin or soft tissue infections. The most

common infections are UTIs followed by bacteremia and then meningitis. In infants less that 1 month old

the rate of SBI is 9-14% and in infants between 1 and 2 months old the rate is 5-9%.

Group B streptococcus, Escherichia coli, Listeria monocytogenes, and herpes simplex virus are the most

common bacterial illnesses in the

7/28/2019 Fever Without a Source

2/2

antibiotics after an LP is performed. Low risk infants can be treated as outpatients or inpatients taking into

consideration the needs of the family, primary care judgment, outpatient follow-up, and communication

with primary care provider (PCP). If antibiotics are given, a third generation cephalosporin should be used.

Ampicillin or vancomycin may be considered if the patient looks ill or UTI, enterococcus, listeria or gram

positive cocci are considered.

High Risk (not consistent with one known criteria)

Laboratory Clinical exam

WBC >15000, WBC5WBCs/hpf, leukocyte esterase or nitrite positive poor perfusion

CSF WBC> 22, protein >150mg, glucose 2 seconds

cyanosis

lethargy

inconsolable

poor or no eye contact

mottling

hyper or hypoventilation

2 months - 3 years

EPIDEMIOLOGY/DIFFERENTIAL: Fever with no identifiable source in this age group should be furtherinvestigated if >39.0 C or 102.2 F. The most common cause is viral but bacterial infections are possible

including UTIs, bacteremia, pneumonia, osteomyelitis, focal skin infections and meningitis.

Prior the HIB and PCV7 vaccines, occult bacteremia caused by strep pneumoniae and H. Influenzae type B

were of concern. The prevalence of occult bacteremia was estimated to be between 3-11% prior to the HIB

vaccine. With both the PCV7 and HIB vaccine, the prevalence has decreased to less than 1%. The risk of

meningitis or death in those with bacteremia is approximately 1.8%.

PRESENTATION: Older infants and toddlers can present with fever and no localizing signs. A careful

history and physical is always necessary. Those with fevers >40 C have a higher likelihood of occult

bacteremia, however many children with temperatures 6 months, males

uncircumcised >1 year, females >2 years and no history of UTI) and have been immunized can be managed

at home without a laboratory evaluation. This should only be done if there is reliable follow-up,

anticipatory guidance is given and the PCP and caregivers are in agreement or when there is a recognizable

viral condition (general URI and acute gastroenteritis not included).

In those at risk for UTI a urinalysis and urine culture should be performed (males circumcised < 6 months,

males uncircumcised 10.000 or WBC >15000) IM ceftriaxone should be considered. Antibiotics are not recommended for

those without a source of bacterial infection in the absence of a laboratory work up.

Patients should be admitted if they are unable to tolerate oral intake, follow up is unavailable, respiratory

distress, hypoxemia or clinical concern is present.