Acute fever without a focus in infants and children

Urine tests (before any antibiotic)

• Urine dipstick (in the practice, on midstream urine if possible)
• Urine microscopy and culture (if leucocytes or nitrites positive on the dipstick, or if intermediate risk of serious illness)if needednon-French guidelineNICE says to send urine for culture if the dipstick shows leucocytes or nitrites, in suspected pyelonephritis, intermediate or high risk of serious illness, recurrent urinary tract infections, or discordance between the clinical picture and the dipstick ^[2]. Collect before any antibiotic ^[2].

• Does not replace clinical assessment (NICE traffic-light system) or paediatric opinion: result to be obtained the same day, child re-examined at a set time with the result.

Laboratory tests (the same day)

• FBC (if laboratory tests are chosen: see the situations in the note)if needednon-French guidelineInfant aged 61 to 90 days in good general condition who is not being referred: the Canadian Paediatric Society accepts FBC, CRP or procalcitonin, blood culture and urinalysis to stratify risk ^[7]. “Amber” child aged 3 months or over: one of the tests that NICE has done in a paediatric setting ^[3].
• CRP (if laboratory tests are chosen: see the situations in the note)if needednon-French guideline“Amber” child when paediatric advice cannot be reached: in Belgian general practice, a CRP < 5 mg/L ruled out serious infection, but 3 of the 7 serious infections had a CRP < 20 mg/L (trial, not a recommendation) ^[8]. Prolonged fever in an infant under 6 months: documented inflammation with no other cause raises suspicion of incomplete Kawasaki disease ^[9]. Under 3 months, low-risk criterion: CRP ≤ 20 mg/L (Step-by-Step method) ^[7].
• Procalcitonin (infant under 3 months, if available the same day)if needednon-French guidelineInfant aged 90 days or less: marker of choice when available; low risk if < 0.5 ng/mL (Step-by-Step method, 22 to 90 days) or ≤ 1.71 ng/mL (PECARN rule) ^[7]. NICE does not mention it in the older child ^[3].

Urine tests (before any antibiotic)

• Urine microscopy and culture (infant under 3 months, even if the dipstick is negative)if needednon-French guidelineEvery febrile infant aged 90 days or less must have urinalysis and urine culture ^[7]; from 61 to 90 days, this is the minimum asked for by the Canadian Paediatric Society ^[7]. After 3 months, see the dipstick in the “NICE version” tab.

• Fever ≥ 38 °C before 3 months: refer the same day to the paediatric emergency department, without prior tests in the community.
• The tests (FBC, CRP or procalcitonin, blood culture, urine microscopy and culture, lumbar puncture depending on age and risk) are done in hospital.

• Life-threatening sign or spreading purpura: call the emergency medical service (SAMU, 15); no sampling should delay treatment.
• "Red" sign without immediate threat to life: urgent paediatric opinion (paediatric emergency department), without prior tests in the community.

Urgent laboratory tests, the same day

• Blood film and thick film (or rapid diagnostic test combined with the blood film): malaria screen
• FBC with platelets
• State on the request form the country and the date of return, and the malaria chemoprophylaxis or treatment taken. The result must be returned within 4 hours of sampling: if this is not possible, refer to the paediatric emergency department.

12 to 24 hours later, if the first result is negative or doubtful

• Blood film and thick film (or rapid diagnostic test combined with the blood film): repeat malaria screenif neededFirst result negative or doubtful while malaria remains possible: the combination of blood film and rapid diagnostic test does not have optimal sensitivity, and the diagnosis must be repeated 12 to 24 hours later ^[11].