Viral Fever in Children

Viral fever in children is fever (temperature 38.0 C or above) caused by a viral infection, the commonest reason for paediatric consultation. Children have 4 to 8 viral infections per year, rising with attendance at childcare.

• Common viruses: rhinovirus, respiratory syncytial virus, influenza, parainfluenza, adenovirus, enteroviruses (including hand, foot and mouth disease), rotavirus and norovirus, human herpesvirus 6 and 7 (roseola), parvovirus B19, Epstein-Barr virus, cytomegalovirus, measles, varicella, dengue (endemic areas), COVID-19.
• Fever is a protective physiological response; the height of the temperature does not reliably predict severity. Most viral fevers resolve in 2 to 5 days (adenovirus and influenza may last 5 to 7 days).
• The main task is to distinguish self-limiting viral illness from serious bacterial infection (sepsis, meningitis, pneumonia, urinary tract infection, bone and joint infection), malaria in endemic areas or after travel, and Kawasaki disease.
• Highest risk groups: age under 3 months (any fever 38.0 C or above), 3 to 6 months with temperature 39.0 C or above, immunocompromised children, children with chronic disease, unvaccinated children, travel to malaria areas.

• Fever with coryza, cough, sore throat, red eyes, rash (viral exanthem), vomiting, diarrhoea, myalgia, irritability, reduced appetite; the child remains alert, plays between fever spikes, drinks, passes urine, and looks well when the temperature falls.
• Assess hydration (mucous membranes, capillary refill, fontanelle, urine output), respiratory rate, work of breathing, heart rate, oxygen saturation, skin colour, rash (non-blanching), neck stiffness, bulging fontanelle, ear, throat, chest, abdomen, joints, genitalia.
• Normal values for assessment by age (respiratory rate per minute, heart rate per minute): under 1 year 30 to 40 and 110 to 160; 1 to 2 years 25 to 35 and 100 to 150; 3 to 5 years 25 to 30 and 95 to 140; 6 to 11 years 20 to 25 and 80 to 120.
• Red flags (urgent assessment): age under 3 months with fever; pale, mottled, ashen or blue skin; no response to social cues; weak, high pitched or continuous cry; drowsy or hard to rouse; grunting, respiratory rate above 60, chest indrawing, saturation under 95 percent; tachycardia; capillary refill over 3 seconds; reduced urine output or sunken fontanelle; non-blanching rash; neck stiffness; bulging fontanelle; seizure; bile stained vomiting; focal swelling or limb non-use; fever for 5 days or longer (Kawasaki disease: conjunctival injection, cracked lips, strawberry tongue, extremity changes, cervical lymphadenopathy); travel to or residence in a malaria endemic area; severe abdominal pain.

• Clinical assessment of risk. No tests are needed for a well appearing child with a clear viral source.
• Urinalysis and culture (clean catch or catheter) for children under 3 years with fever and no source; urine dipstick positive nitrites or leucocytes warrants culture.
• Fever without source or toxic appearance: full blood count, CRP (above 20 mg/L raises concern for bacterial infection; above 80 mg/L high), blood culture, blood glucose, electrolytes; chest X-ray for tachypnoea, hypoxia or persistent fever with cough; lumbar puncture in infants under 3 months and any child with meningism.
• Malaria rapid diagnostic test and thick and thin blood smears for any febrile child in an endemic area or with travel history, within 24 hours; dengue NS1 or PCR if relevant.
• Throat swab and respiratory viral PCR (influenza, RSV, COVID-19) when results change management.
• Bacterial markers (procalcitonin) can assist where available.

• Home care for a well child: dress lightly, keep room comfortable, offer frequent fluids (breast milk or formula, oral rehydration solution 10 mL/kg after each loose stool or vomit), do not sponge with cold water or alcohol, no antipyretic needed if the child is comfortable.
• Antipyretic only to relieve distress:
  • Paracetamol 15 mg/kg orally every 4 to 6 hours, maximum 4 doses (60 mg/kg) in 24 hours (suspension 120 mg/5 mL or 250 mg/5 mL; avoid under 1 month unless prescribed).
  • Ibuprofen 5 to 10 mg/kg orally every 6 to 8 hours with food, maximum 30 mg/kg in 24 hours; age over 3 months and weight over 5 kg; avoid with dehydration, vomiting, asthma exacerbation, renal disease, chickenpox or bleeding disorder.
  • Do not give aspirin (Reye syndrome). Alternating or combining antipyretics is not recommended routinely.
  • Antipyretics do not prevent febrile seizures.
• Antibiotics are not indicated for viral fever. Start antibiotics promptly for confirmed or suspected bacterial infection (urinary tract infection, pneumonia, otitis media, sepsis).
• Specific antivirals: oseltamivir for influenza in high risk children or severe disease (weight up to 15 kg: 30 mg twice daily; over 15 to 23 kg: 45 mg twice daily; over 23 to 40 kg: 60 mg twice daily; over 40 kg: 75 mg twice daily for 5 days).
• Malaria positive: treat promptly (artemether lumefantrine for uncomplicated falciparum malaria by weight over 3 days: 5 to under 15 kg 1 tablet per dose; 15 to under 25 kg 2 tablets; 25 to under 35 kg 3 tablets; 35 kg and over 4 tablets; given at 0, 8, 24, 36, 48 and 60 hours with fatty food); severe malaria needs intravenous artesunate 2.4 mg/kg at 0, 12, 24 hours then daily.
• Admission: sepsis features, dehydration unresponsive to oral rehydration, hypoxia, age under 3 months, persistent vomiting, parental anxiety with inability to cope, fever lasting 5 days or more with other features.
• Safety netting: return urgently for drowsiness, breathing difficulty, rash that does not fade on pressure, fits, persistent vomiting, no urine for 8 to 12 hours, worsening, or fever beyond 5 days.
• Review in 24 to 48 hours if no clear source or if symptoms persist.