Fever Without Source in Children

Fever without source is an acute fever (38 °C or more) of under 7 days in a child, with no cause evident after careful history and examination.

• Most cases are self-limited viral infections.
• The main concern is occult serious bacterial infection: urinary tract infection, bacteraemia, meningitis, pneumonia and osteoarticular infection.
• In Kenya and other malaria-endemic areas, malaria must be excluded in every febrile child.
• Risk is highest under 3 months (neonates under 28 days especially), in unimmunised children, and in children who are unwell, immunocompromised or have sickle cell disease or HIV.
• Risk assessment rests on age, appearance and focused investigations.

The child may be well or ill-looking.

• Temperature of 38 °C or more by thermometer, with no localising symptoms or signs.
• Well-appearing: alert, feeds, consolable and normal colour.
• Ill-appearing: lethargy, poor feeding, mottled skin, grunting, tachypnoea, reduced urine output, weak cry, or a bulging fontanelle.
• Check for tachycardia, prolonged capillary refill (over 2 seconds), and a non-blanching rash.
• Examine ears, throat, chest, abdomen, skin, joints, spine and genitalia.
• Differential diagnosis: viral infection, urinary tract infection, early pneumonia, malaria, typhoid, meningitis, sepsis, bacteraemia, osteomyelitis, Kawasaki disease, and drug fever.
• Complications: septic shock, meningitis, sepsis, febrile seizure, dehydration and delayed diagnosis of serious illness.

Investigation depends on age and appearance.

• Under 28 days: full sepsis workup for all (full blood count, C-reactive protein, blood culture, urine culture, lumbar puncture), regardless of appearance.
• 1 to 3 months: full blood count, C-reactive protein, urinalysis and culture, blood culture. Lumbar puncture for ill-appearing or high-risk infants.
• 3 months to 3 years: urinalysis and urine culture (clean catch or catheter specimen) in all febrile girls under 3 years, uncircumcised boys under 1 year, and circumcised boys under 6 months.
• Malaria rapid diagnostic test or blood film in all.
• Full blood count and C-reactive protein for ill-looking children or fever above 39 °C for more than 48 hours.
• Chest X-ray if respiratory signs or white cell count above 20,000 per microlitre.
• HIV testing, blood glucose, and typhoid tests (blood culture) if persisting fever.

Management is tailored to age and risk.

• Supportive: fluids, rest, light clothing. Do not sponge with cold water.
• Pharmacological, antipyretics for comfort: paracetamol 15 mg/kg every 4 to 6 hours (maximum 60 mg/kg/day), or ibuprofen 5 to 10 mg/kg every 6 to 8 hours (maximum 30 mg/kg/day, not under 3 months).
• Under 3 months, or ill-looking: admit and start empirical intravenous ceftriaxone 50 to 100 mg/kg once daily (not in neonates with jaundice; give cefotaxime 50 mg/kg every 8 hours instead), plus ampicillin 50 mg/kg every 6 hours for neonates and infants under 6 weeks. Add intravenous gentamicin 5 to 7.5 mg/kg once daily where needed. Add aciclovir 20 mg/kg every 8 hours when herpes encephalitis is suspected.
• Positive malaria test: artemether-lumefantrine twice daily for 3 days, dosed by weight band (5 to 14 kg one tablet, 15 to 24 kg two tablets, 25 to 34 kg three tablets, 35 kg or more four tablets per dose).
• Urinary tract infection: oral cefalexin 12.5 mg/kg every 6 hours or amoxicillin-clavulanate 15 mg/kg (amoxicillin component) every 8 hours for 7 to 10 days.
• Well-looking older child with a negative workup: home observation with safety-net advice.
• Procedures: lumbar puncture, urine catheterisation and blood culture where indicated.
• Special groups: sickle cell disease, HIV and immunocompromise need admission and early antibiotics. Children with fever for 5 days or more need assessment for Kawasaki disease.
• Red flags: age under 3 months, non-blanching rash, neck stiffness, bulging fontanelle, seizure, respiratory distress, prolonged capillary refill, lethargy, fever of 5 days or more, and parental concern.
• Follow-up: review within 24 to 48 hours. Return if the child worsens. Fever of 5 days or more needs full reassessment.