Fever in a child

Fever in a child is a core temperature of 38.0 degrees Celsius or over (rectal, or tympanic or axillary readings interpreted with care). It is the commonest reason for children to attend primary care and emergency departments, and most fevers are caused by self limiting viral infections.

Definitions.

• Fever without a source is fever with no cause found after history and examination, usually of less than 7 days duration.
• Hyperpyrexia is a temperature of 41.0 degrees Celsius or over.
• Fever of unknown origin is fever of 38.3 degrees Celsius or over for more than 8 days, without a diagnosis after initial investigation.
• Serious bacterial infection includes bacteraemia, meningitis, urinary tract infection, pneumonia, bone and joint infection, and enteric infection.
• Febrile neutropenia is fever with an absolute neutrophil count under 0.5 x 10^9/L.

Classification by age and cause

• Neonates (under 28 days) and young infants (1 to 3 months): bacterial sepsis (group B Streptococcus, Escherichia coli, Listeria), meningitis, urinary tract infection, herpes simplex virus infection, enterovirus, and omphalitis.
• Infants and children 3 months to 5 years: viral infection (respiratory viruses, enteroviruses, roseola, adenovirus), otitis media, pharyngitis, urinary tract infection, pneumonia, bacteraemia, meningitis, gastroenteritis, measles, malaria and dengue in endemic regions, typhoid, and Kawasaki disease.
• Older children and adolescents: streptococcal pharyngitis, infectious mononucleosis, pneumonia (Mycoplasma), urinary tract infection, appendicitis, osteomyelitis and septic arthritis, meningococcal disease, malaria, typhoid, tuberculosis, HIV, and inflammatory conditions (juvenile idiopathic arthritis, inflammatory bowel disease).
• Noninfectious: Kawasaki disease, multisystem inflammatory syndrome in children, juvenile idiopathic arthritis, malignancy (leukaemia, lymphoma, neuroblastoma), drug fever, overheating, dehydration fever, and vaccine reaction.

Epidemiology. Children under 5 years have 4 to 6 febrile illnesses each year. About 1% to 3% of febrile infants under 3 months have bacteraemia, and 5% to 10% have urinary tract infection. Fever is the presenting feature of invasive bacterial disease, and mortality from childhood sepsis remains high in low resource settings. Malaria remains the leading cause of fever in children in sub-Saharan Africa, with pneumonia, bacteraemia and enteric infection also common. Febrile seizures occur in 2% to 5% of children.

Mechanisms. Pyrogenic cytokines (interleukin-1, interleukin-6, tumour necrosis factor) reset the hypothalamic set point through prostaglandin E2. Fever is a protective response that does not itself cause brain damage under 41.0 degrees Celsius, and the degree of fever does not reliably indicate severity.

Key distinctions. The appearance of the child (alertness, response to social cues, colour, perfusion, breathing, hydration) predicts serious illness better than the temperature. Fever for 5 days or more with red eyes, red cracked lips, rash, cervical lymphadenopathy and swollen hands and feet suggests Kawasaki disease. Fever with purpuric rash suggests meningococcal disease.

Fever with irritability, bulging fontanelle and neck stiffness suggests meningitis. Fever with a chill pattern and recent travel or residence in a malaria area suggests malaria. Fever with an abdominal complaint and stepwise rise suggests typhoid. Fever with refusal to bear weight suggests bone or joint infection.

History

• Fever: duration, height, how measured, pattern, response to antipyretics, rigors.
• Symptoms: cough, rapid breathing, nasal discharge, ear pulling, sore throat, vomiting, diarrhoea, abdominal pain, dysuria or foul urine, rash, limping or refusal to use a limb, headache, neck pain, photophobia, irritability, drowsiness, seizure, and reduced feeding or urine output.
• Perinatal history in infants: gestation, maternal group B Streptococcus status, prolonged rupture of membranes, neonatal intensive care stay, jaundice, and maternal herpes.
• Immunisation: Haemophilus influenzae type b, pneumococcal conjugate, meningococcal, measles, BCG, rotavirus, typhoid, and COVID-19 status.
• Exposures: sick contacts, daycare, siblings, tuberculosis contact, animals, water, travel and residence in malaria or dengue areas, mosquito bites, bed net use, and chemoprophylaxis.
• Past history: immunodeficiency, sickle cell disease, HIV, malnutrition, cardiac disease, previous urinary infections, renal tract abnormality, central lines, shunts, and previous febrile seizures.
• Drugs: antipyretics (dose and timing), antibiotics already given, and allergies.
• Parental concern and ability to observe the child at home.

Examination

• Measure temperature, heart rate, respiratory rate, capillary refill time, oxygen saturation, and weight, and assess hydration and level of alertness. Record blood pressure in ill children.
• Assess using a structured risk system (the traffic light system): green (normal colour, responds normally, smiles, strong cry, moist mucous membranes, no concerning features), amber (pallor reported by parents, not responding normally to social cues, wakes only with prolonged stimulation, decreased activity, nasal flaring, tachypnoea [respiratory rate over 50 breaths/min at 6 to 12 months, over 40 breaths/min over 12 months], oxygen saturation 95% or under, crackles, tachycardia, capillary refill 3 seconds or over, dry mucous membranes, poor feeding in infants, reduced urine output, age 3 to 6 months with temperature 39.0 degrees Celsius or over, fever for 5 days or more, limb swelling or non weight bearing, new lump over 2 cm), red (pale, mottled, ashen or blue, no response to social cues, appears ill, cannot be woken or does not stay awake, weak, high pitched or continuous cry, grunting, respiratory rate over 60 breaths/min, moderate or severe chest indrawing, reduced skin turgor, bulging fontanelle, neck stiffness, status epilepticus, focal neurological signs or focal seizures, bile stained vomiting, age under 3 months with temperature 38.0 degrees Celsius or over, non blanching rash).
• Systematic search for a source: ears, throat, mouth, nose, chest, heart, abdomen, genitalia, hips and joints, spine, skin, lymph nodes, fontanelle, and umbilicus.
• Meningeal signs are unreliable in young infants. Brudzinski and Kernig signs have low sensitivity.
• Signs of Kawasaki disease: bilateral nonexudative conjunctival injection, oral changes (strawberry tongue, red cracked lips), polymorphous rash, extremity changes (oedema, erythema, later peeling), and cervical lymphadenopathy over 1.5 cm.
• Sepsis recognition: tachycardia, tachypnoea, hypotension (late sign in children), altered mental state, mottled skin, prolonged capillary refill, and low urine output.

Red flags

• Age under 3 months with fever of 38.0 degrees Celsius or over (any illness appearance).
• Any red feature in the traffic light system.
• Non blanching rash, shock, altered consciousness, seizure with continuing drowsiness, or meningism.
• Respiratory distress (grunting, recession, cyanosis, oxygen saturation under 92%).
• Persistent fever over 5 days (Kawasaki disease, bacterial infection, tuberculosis, malignancy).
• Bile stained vomiting, abdominal distension, or severe abdominal pain.
• Limb pain with refusal to bear weight, or swollen painful joint.
• Immunosuppression, central line, sickle cell disease, asplenia, or neutropenia.
• Recent travel to a malaria area, or residence in a malaria endemic area.
• Signs of dehydration or severe malnutrition.
• Fever with petechiae and neutropenia or thrombocytopenia.
• Fever after a bite or in the presence of a spreading skin infection.
• Safeguarding concerns: injuries, neglect, or delay in presenting.

Special groups

• Neonates and infants under 3 months: examine fully, test the urine, blood and cerebrospinal fluid, admit for antibiotics.
• Immunocompromised and children with central lines: assume febrile neutropenia until the neutrophil count is known.
• Malnourished children: fever and hypothermia are both warning signs; sepsis presents without typical signs.
• Children with sickle cell disease: fever over 38.5 degrees Celsius is an emergency because of pneumococcal sepsis risk.
• Region specific: malaria, typhoid, tuberculosis, HIV, measles, dengue, rickettsial disease, and brucellosis.

Viral infection (the majority)

• Upper respiratory infection, influenza, COVID-19, respiratory syncytial virus, adenovirus, enteroviruses, parechovirus.
• Roseola (human herpesvirus 6), hand foot and mouth disease, herpangina, gingivostomatitis (herpes simplex), measles, varicella, infectious mononucleosis, and viral gastroenteritis.

Bacterial infection

• Otitis media, pharyngitis and tonsillitis, sinusitis, and cervical lymphadenitis.
• Pneumonia, bronchiolitis with secondary infection, and pertussis.
• Urinary tract infection and pyelonephritis.
• Bacteraemia, sepsis, meningitis, meningococcal disease.
• Osteomyelitis, septic arthritis, cellulitis, abscess, and omphalitis.
• Enteric fever, bacterial gastroenteritis, and appendicitis.
• Tuberculosis, brucellosis, and rickettsial infection.
• Toxic shock syndrome.

Parasitic and tropical

• Malaria (including cerebral malaria).
• Dengue, chikungunya, visceral leishmaniasis, schistosomiasis, trypanosomiasis.

Noninfectious

• Kawasaki disease and multisystem inflammatory syndrome in children.
• Juvenile idiopathic arthritis (systemic onset), systemic lupus erythematosus, vasculitis, and periodic fever syndromes.
• Leukaemia, lymphoma, neuroblastoma, and other malignancy.
• Inflammatory bowel disease.
• Drug fever, serum sickness, immunisation reaction, thyrotoxicosis.
• Overwrapping, high environmental temperature, dehydration fever (neonate), heat stroke.

Step 1. Assess for sepsis and stabilise. Evaluate airway, breathing, circulation, disability, and glucose. Treat red features urgently. Take cultures and give antibiotics without delay when the child has sepsis.

Step 2. Stratify by age and risk

• Under 28 days with temperature 38.0 degrees Celsius or over: full sepsis evaluation, lumbar puncture, and admission with antibiotics regardless of appearance.
• 1 to 3 months with temperature 38.0 degrees Celsius or over: full blood count, C-reactive protein, blood culture, urine culture, and, if the child appears ill or has high risk markers (white cell count under 5 or over 15 x 10^9/L, C-reactive protein over 20 mg/L, abnormal urinalysis, procalcitonin over 0.5 ng/mL), lumbar puncture and admission. Well appearing infants meeting low risk criteria may be managed by senior decision with close follow up.
• 3 months and over: risk assess with the traffic light system, look for a source, and test by the clinical picture.

Step 3. First line tests

• Urine: clean catch, catheter or suprapubic aspirate (bag specimens are unreliable) for dipstick, microscopy and culture in children with unexplained fever, in all infants under 3 months, and in febrile children with urinary symptoms. Dipstick positive leucocyte esterase or nitrite suggests infection.
• Full blood count, C-reactive protein, blood culture, and, in amber or red children without a source, urea, electrolytes, glucose, and lactate.
• Malaria rapid test or blood film in any child with fever from or recently in an endemic area (and haemoglobin and glucose).
• Chest radiograph for tachypnoea, hypoxia, persistent cough with fever, or fever over 39.0 degrees Celsius with raised white cell count and no source.
• Throat swab or rapid antigen test when sore throat is present.
• Stool culture and microscopy for bloody or persistent diarrhoea.

Step 4. Targeted tests

• Lumbar puncture for suspected meningitis, infants under 28 days, and unexplained fever in ill infants (after stabilisation, with delayed lumbar puncture if there is coagulopathy, cardiovascular instability, respiratory compromise, or signs of raised intracranial pressure; do not delay antibiotics).
• Cerebrospinal fluid: cell count (more than 20 cells/microlitre in neonates, 5 in older children), protein, glucose with paired blood glucose, Gram stain, culture, and polymerase chain reaction for herpes simplex virus and enterovirus.
• Procalcitonin as an additional marker of bacterial infection in young infants.
• Ultrasound of kidneys and bladder after a first febrile urinary infection in infants (and later imaging as directed), echocardiography in suspected Kawasaki disease (at diagnosis and at 1 to 2 weeks and 4 to 6 weeks), and joint or hip ultrasound.
• Magnetic resonance imaging for suspected osteomyelitis or intracranial infection, and plain radiographs (changes appear after 7 to 14 days).
• Erythrocyte sedimentation rate, ferritin, liver tests, albumin, troponin and B-type natriuretic peptide in Kawasaki disease or multisystem inflammatory syndrome.
• Widal is unreliable; typhoid is diagnosed by blood culture. Dengue NS1 antigen and serology; HIV test; tuberculosis tests (tuberculin skin test or interferon gamma release assay, gastric aspirate or sputum Xpert MTB/RIF).
• Blood film for sickle cells, bone marrow if cytopenias, and blood tests for leukaemia (smear, lactate dehydrogenase, uric acid) when unexplained cytopenias or bone pain occur.

Step 5. Interpretation. Most febrile children with no red features have a self limiting viral illness. Fever lasting 5 days or more needs a search for Kawasaki disease. A raised C-reactive protein over 80 mg/L, white cell count over 20 x 10^9/L, or procalcitonin over 2 ng/mL indicates serious bacterial infection in many children but not all. A positive urine dipstick is highly specific for infection when supported by culture. A normal chest radiograph does not exclude early pneumonia.

Limits. Temperature does not predict serious illness. Cultures take 24 to 48 hours. In malaria endemic areas, a positive rapid test may be incidental parasitaemia and not the cause of fever, so always look for other causes. Antipyretic response does not distinguish serious from benign illness.

Immediate: sepsis and septic shock (red features, shock, or suspected meningitis)

• Oxygen to saturation 94% or over, intravenous or intraosseous access, blood glucose, blood cultures, full blood count, lactate, urea and electrolytes, and venous gas.
• Fluid resuscitation: isotonic crystalloid 10 mL/kg boluses in malnourished children, 10 to 20 mL/kg boluses in other children over 5 to 10 minutes (up to 40 to 60 mL/kg in the first hour), reassessing after each bolus for signs of fluid overload (crackles, hepatomegaly, increased work of breathing). Start adrenaline 0.05 to 0.3 micrograms/kg/minute if shock persists after 40 to 60 mL/kg.
• Antibiotics within 1 hour: ceftriaxone 80 mg/kg intravenously (maximum 4 g) once daily (50 mg/kg every 12 hours is an alternative) for children over 1 month. Neonates under 28 days: amoxicillin or ampicillin 50 mg/kg intravenously every 6 to 8 hours (100 mg/kg every 6 hours for meningitis) plus gentamicin 5 mg/kg intravenously every 24 hours (term neonates, with levels) or cefotaxime 50 mg/kg every 6 to 8 hours (every 12 hours in the first week); add aciclovir 20 mg/kg intravenously every 8 hours for neonates with suspected herpes simplex virus infection (vesicles, seizures, raised liver enzymes, maternal history).
• Infants over 1 month with meningitis: ceftriaxone 100 mg/kg once daily (maximum 4 g) or 50 mg/kg every 12 hours (maximum 2 g) with dexamethasone 0.15 mg/kg (maximum 10 mg) every 6 hours for 4 days, started with or before the first antibiotic dose, and add vancomycin 15 mg/kg every 6 hours in regions with penicillin resistant pneumococci. Duration 7 to 10 days for pneumococcus, 5 to 7 days for meningococcus, 7 days for Haemophilus, 14 to 21 days for Listeria and group B Streptococcus (21 days in neonates).
• Glucose: if under 3.0 mmol/L give 10% dextrose 2 mL/kg intravenously.
• Seizure: lorazepam 0.1 mg/kg (maximum 4 mg) intravenously, or midazolam 0.3 mg/kg buccal (maximum 10 mg) or 0.2 mg/kg intranasal.
• Severe malaria: artesunate 2.4 mg/kg intravenously at 0, 12 and 24 hours, then once daily (3 mg/kg for each dose in children under 20 kg), until oral treatment is possible, followed by a full oral artemisinin combination course; glucose monitoring every 4 hours.

Fever control and general care

• Treat distress, not temperature alone. Antipyretics are for comfort and do not prevent febrile seizures. Do not use alternating or combined antipyretics routinely.
• Paracetamol 15 mg/kg orally every 4 to 6 hours (maximum 60 mg/kg daily and 4 doses in 24 hours; maximum single dose 1 g), from age 1 month (in infants 1 to 3 months, 10 to 15 mg/kg every 6 to 8 hours); rectal 20 mg/kg initial dose in vomiting children.
• Ibuprofen 5 to 10 mg/kg orally every 6 to 8 hours (maximum 30 mg/kg daily, maximum single dose 400 mg) from age 3 months and weight over 5 kg, with food; avoid in dehydration, kidney disease, bleeding disorders, asthma exacerbation, and varicella.
• Do not use aspirin in children under 16 years except for Kawasaki disease under specialist care.
• Offer fluids frequently (oral rehydration solution if dehydrated), continue breastfeeding and feeding, dress lightly, avoid tepid sponging and cooling by fans or cold baths.

Specific infections

• Acute otitis media: analgesia, and antibiotic if under 6 months, bilateral under 2 years, perforation with discharge, severe symptoms, or no improvement in 48 to 72 hours: amoxicillin 40 to 45 mg/kg orally twice daily (or 30 mg/kg three times daily; up to 80 to 90 mg/kg daily in two doses in settings with resistance) for 5 days (7 to 10 days under 2 years).
• Pharyngitis (group A Streptococcus, Centor 3 or more or positive test): phenoxymethylpenicillin 12.5 mg/kg (maximum 500 mg) four times daily or 25 mg/kg twice daily (maximum 1 g) for 10 days, or amoxicillin 50 mg/kg once daily (maximum 1 g) for 10 days; benzathine benzylpenicillin 600,000 units (under 27 kg) or 1.2 million units intramuscularly once. Penicillin allergy: azithromycin 12 mg/kg once daily (maximum 500 mg) for 5 days.
• Community acquired pneumonia: amoxicillin 40 to 50 mg/kg orally twice daily (maximum 1 g for each dose) for 5 days; severe or admitted: benzylpenicillin 50 mg/kg every 6 hours or ampicillin 50 mg/kg every 6 hours intravenously, plus oxygen. Atypical pneumonia in school age children: azithromycin 10 mg/kg on day 1 then 5 mg/kg daily for 4 days.
• Urinary tract infection: oral cefalexin 25 mg/kg twice daily (maximum 500 mg) or amoxicillin with clavulanic acid 15 mg/kg of the amoxicillin component every 8 hours (maximum 500 mg) for 7 to 10 days (3 days for lower tract infection in older children); intravenous ceftriaxone 50 to 75 mg/kg once daily or gentamicin 5 to 7.5 mg/kg once daily for infants under 3 months or ill children.
• Bone and joint infection: flucloxacillin 50 mg/kg (maximum 2 g) intravenously every 6 hours, plus ceftriaxone 50 mg/kg daily in infants or when Haemophilus is possible, clindamycin 10 mg/kg every 6 to 8 hours (maximum 600 mg) when MRSA is suspected; early switch to oral therapy for a total of 3 to 6 weeks (shorter for uncomplicated septic arthritis); orthopaedic review for drainage.
• Typhoid fever: ceftriaxone 75 mg/kg once daily (maximum 2 g) for 10 to 14 days, or azithromycin 20 mg/kg once daily (maximum 1 g) for 7 days.
• Measles: supportive care, vitamin A 200,000 international units orally once daily for 2 days (100,000 units for 6 to 11 months; 50,000 units under 6 months), and antibiotics for secondary bacterial infection.
• Uncomplicated malaria: artemether with lumefantrine by weight band (5 to under 15 kg: 1 tablet; 15 to under 25 kg: 2 tablets; 25 to under 35 kg: 3 tablets; 35 kg or over: 4 tablets) at 0, 8, 24, 36, 48 and 60 hours with fatty food.
• Dengue: oral fluids and paracetamol, avoid nonsteroidal drugs, and monitor haematocrit and platelets daily from day 3.
• Diarrhoeal dehydration: oral rehydration solution 50 to 100 mL/kg over 3 to 4 hours with zinc 20 mg daily for 10 to 14 days (10 mg daily in infants under 6 months).
• Viral illness: supportive care, and no antibiotics.

Kawasaki disease

• Intravenous immunoglobulin 2 g/kg as a single infusion over 10 to 12 hours, ideally within 10 days of fever onset, with aspirin 30 to 50 mg/kg daily in four divided doses until afebrile for 48 to 72 hours (some centres use 3 to 5 mg/kg once daily from the start), then 3 to 5 mg/kg once daily for 6 to 8 weeks or until the echocardiogram is normal. Persistent fever beyond 36 hours after infusion: repeat immunoglobulin 2 g/kg or give methylprednisolone 2 mg/kg daily with taper, or infliximab 5 mg/kg. Add corticosteroids in high risk children. Echocardiogram at diagnosis, 1 to 2 weeks, and 4 to 6 weeks. Aneurysms need anticoagulation or antiplatelet therapy under cardiology. Defer live vaccines for 11 months after immunoglobulin.

Multisystem inflammatory syndrome in children

• Admit with cardiac monitoring, give immunoglobulin 2 g/kg and methylprednisolone 1 to 2 mg/kg daily, and aspirin 3 to 5 mg/kg daily, under specialist care.

Febrile neutropenia in children

• Piperacillin with tazobactam 100 mg/kg of piperacillin every 8 hours (maximum 4 g every 6 hours) or meropenem 20 mg/kg every 8 hours (maximum 1 g), within 1 hour, with gentamicin 7 mg/kg once daily if shock.

Sickle cell disease with fever

• Fever of 38.5 degrees Celsius or over: urgent assessment, blood culture, ceftriaxone 50 to 80 mg/kg intravenously immediately, and admission for ill children.

Disposition

• Admit: any red feature, age under 3 months (all febrile neonates and most infants under 3 months), shock, meningitis, sepsis, respiratory distress, dehydration, bone or joint infection, Kawasaki disease, febrile neutropenia, immunodeficiency, malnutrition, inability to take fluids, uncertainty and unreliable follow up.
• Observe (up to 2 to 6 hours) children with amber features and then reassess; discharge only with safety net advice.
• Discharge green children with clear advice.

Special populations

• Neonates: a normal appearance is not reassuring. Do a full sepsis evaluation and give antibiotics.
• Malnourished children: ceftriaxone 80 mg/kg daily plus gentamicin 7.5 mg/kg daily for severe malnutrition with sepsis, and cautious fluids (10 mL/kg over 1 hour).
• HIV: broaden the search to tuberculosis, Pneumocystis, and bacteraemia (including Salmonella).
• Renal and hepatic impairment: adjust doses of aminoglycosides and antipyretics.

Monitoring. Temperature, heart rate, respiratory rate, oxygen saturation, capillary refill, consciousness and urine output (hourly for ill children), blood glucose, culture results at 24 to 48 hours, C-reactive protein trends, gentamicin levels, and echocardiography in Kawasaki disease.

Referral and escalation. Paediatric senior review for all red features. Intensive care for shock, respiratory failure or neurological compromise. Paediatric infectious diseases for resistant infection, bone and joint disease, and immunodeficiency. Cardiology for Kawasaki disease and multisystem inflammatory syndrome. Oncology for suspected malignancy. Safeguarding when injuries or neglect are suspected.

Admission criteria. As listed under disposition.

Discharge and follow up. Written and verbal advice on recognising deterioration, fluids, antipyretic doses, and when to seek help. Review in 24 to 48 hours if no cause is found and symptoms persist, and for fever lasting 5 days, refer for assessment of Kawasaki disease. Safety net advice: return at once for drowsiness or difficult waking, fast or difficult breathing, a rash that does not fade under a pressed glass, a stiff neck, bulging fontanelle, seizure, persistent vomiting, no urine in 8 hours, cold limbs or mottled skin, severe pain, or worsening.