Identifying Severe Influenza ("Superflu") in Children by Signs and Symptoms
You should immediately seek medical evaluation if a child with influenza-like illness develops any of the following red flag signs: respiratory distress (grunting, intercostal retractions, markedly elevated respiratory rate), cyanosis, altered consciousness or extreme drowsiness, prolonged or complicated seizures, signs of septicemia (extreme pallor, hypotension, floppy infant), or severe dehydration. 1
Age-Specific Warning Signs
Neonates (0-2 months)
- Non-specific sepsis signs: pallor, floppiness (poor tone), lethargy, poor feeding, apneic episodes 1
- Fever may be the only presenting feature, but its presence warrants immediate evaluation 1
Infants and Young Children (<2 years)
- High fever (>38.5°C) combined with any of the following 1:
- Repeated febrile convulsions (influenza causes more recurrent seizures than other febrile illnesses) 1, 2
- Extreme irritability or appearing "toxic" 1
Older Children (>2 years)
- Sudden onset of high fever with cough, headache, and pharyngitis (this triad has 80% sensitivity for influenza) 1
- Red flags for severe disease 1:
- Breathlessness with chest signs
- Cyanosis
- Altered mental status (confusion, extreme lethargy, personality changes)
- Complicated or prolonged seizures
Critical Complications to Recognize
Bacterial Superinfection (20-38% of severe cases)
The hallmark presentation is initial improvement followed by fever recurrence 3. This pattern strongly suggests secondary bacterial pneumonia from S. pneumoniae, S. aureus, or H. influenzae 3. Children with influenza are 12 times more likely to develop severe pneumococcal complications 3, 4.
Encephalopathy/Encephalitis
- Altered mental status, seizures, or extreme irritability persisting beyond 24 hours 1, 3
- Neck pain with fever should raise immediate concern for encephalopathy 4
- This complication has devastating outcomes: 31% mortality, 26% permanent neurological deficit, only 43% full recovery 2
Acute Respiratory Distress Syndrome
- Progressive respiratory distress with rising respiratory and pulse rates 1
- Failure to maintain oxygen saturation >92% despite high oxygen delivery (FiO2 >60%) 1
- Elevated CO2 (PaCO2 >6.5 kPa) with severe respiratory distress 1
High-Risk Features Requiring Medical Assessment
Children with fever >38.5°C and influenza-like symptoms PLUS any of the following need immediate physician evaluation 1:
- Chronic comorbid conditions (respiratory disease, cardiac disease, immune compromise, non-ambulant status) 1
- Age <1 year (12 times higher admission rate than older children) 1
- Breathing difficulties of any degree 1
- Persistent vomiting (>24 hours) 1
- Severe earache (otitis media occurs in ~25% of children <5 years with influenza) 3, 2
- Drowsiness or lethargy 1
Common Pitfalls to Avoid
Do not wait for "classic" influenza symptoms in young children. In infants, fever with non-specific symptoms or isolated gastrointestinal symptoms (diarrhea, vomiting) is common and does not rule out severe disease 1. Rhinitis is present in 78% of cases, making clinical diagnosis difficult in the youngest children 5.
Do not dismiss fever persisting beyond 4 days. This indicates possible complications rather than typical influenza and requires physician evaluation 3.
Do not delay evaluation for altered mental status. Even subtle changes in consciousness, extreme irritability, or personality changes warrant urgent assessment for encephalopathy, which progresses rapidly 3, 2.
When to Refer for Hospital Admission
Immediate hospital referral is indicated for 1:
- Signs of respiratory distress (markedly raised respiratory rate, grunting, intercostal recession, breathlessness with chest signs)
- Cyanosis
- Severe dehydration
- Altered conscious level
- Complicated or prolonged seizure
- Signs of septicemia (extreme pallor, hypotension, floppy infant)