What is the diagnosis and management approach for a 9-year-old girl with a fever of 5 days duration?

Kawasaki Disease Must Be Ruled Out Urgently

A 9-year-old girl with 5 days of fever requires immediate evaluation for Kawasaki disease, which is the most critical diagnosis to exclude given the risk of coronary artery aneurysms if treatment is delayed beyond 10 days of fever onset. 1

Immediate Diagnostic Approach

Clinical Criteria Assessment

Evaluate for the four principal clinical features of Kawasaki disease (in addition to the 5-day fever already present): 1

• Bilateral non-purulent conjunctival injection (bulbar conjunctiva with limbal sparing, no photophobia or eye pain) 1
• Oral mucosal changes (red cracked lips, strawberry tongue, or diffuse oral erythema without ulcerations or exudates) 1
• Polymorphous rash (typically truncal, maculopapular, may be urticarial or scarlatiniform; never bullous or vesicular) 1
• Extremity changes (erythema of palms/soles, painful edema of hands/feet with sharp demarcation at wrists/ankles) 1
• Cervical lymphadenopathy (≥1.5 cm diameter, often unilateral, least common feature) 1

If 4 of 5 principal features are present with the fever, diagnose Kawasaki disease immediately and initiate treatment. 1

Incomplete Kawasaki Disease Algorithm

If only 2-3 principal features are present with the 5-day fever: 1, 2

1. Obtain inflammatory markers immediately: 1, 2

   • ESR (typically >40 mm/hr, often ≥100 mm/hr)
   • CRP (typically ≥3 mg/dL or 30 mg/L)

2. If inflammatory markers are elevated, obtain: 1, 2

   • Complete blood count with differential
   • Serum albumin
   • Serum transaminases (ALT, AST)
   • Urinalysis (looking for sterile pyuria)

3. Perform urgent echocardiography if: 1, 3

   • Laboratory evidence of inflammation is present
   • Any coronary artery abnormalities on echo confirm the diagnosis even with only 3 clinical features

Immediate Treatment Protocol

If Kawasaki disease is diagnosed, treatment must be initiated urgently: 1

• IVIG 2 g/kg as a single infusion (first-line therapy, Grade A evidence) 1
• High-dose aspirin 80-100 mg/kg/day divided into 4 doses (for anti-inflammatory effect) 1
• Treatment should ideally occur within 10 days of fever onset to prevent coronary artery aneurysms (risk increases from 25% untreated to 5% with treatment, and <1% for giant aneurysms) 1

Aspirin Dosing Transition

• Continue high-dose aspirin until 48-72 hours after defervescence or 14 days after symptom onset 1
• Then reduce to low-dose aspirin 3-5 mg/kg/day (single daily dose) for antiplatelet effect 1
• Continue low-dose aspirin for 6-8 weeks if no coronary abnormalities, or indefinitely if abnormalities present 1

Critical Pitfalls to Avoid

Do not wait for all clinical features to appear simultaneously - they often evolve over time, and careful history-taking may reveal features that were present earlier but have resolved. 1

Do not dismiss the diagnosis in older children - while Kawasaki disease is most common in children under 5 years, it occurs in all age groups, and cervical lymphadenopathy may be the most prominent presenting sign in older children. 1

Avoid ibuprofen in children taking aspirin as it antagonizes aspirin's antiplatelet effect. 1

Ensure influenza and varicella vaccination are up to date or administer after acute phase, as Reye's syndrome risk exists with aspirin use during these infections. 1

Alternative Diagnoses to Consider

If Kawasaki disease is excluded, evaluate for: 1, 2

• Viral infections (measles, adenovirus, enterovirus, Epstein-Barr virus) 1
• Scarlet fever (Group A Streptococcus) 1
• Toxic shock syndrome 1
• Drug hypersensitivity reactions 1
• Rocky Mountain spotted fever (if tick exposure history) 3
• Urinary tract infection (obtain urinalysis and culture via catheterization, not bag specimen) 2

Follow-Up Requirements

If Kawasaki disease is treated: 3

• Repeat echocardiography at 2 weeks and 6-8 weeks after treatment
• Cardiology follow-up for risk stratification
• Continue low-dose aspirin until coronary arteries confirmed normal

If diagnosis remains unclear after initial evaluation: 2

• Serial reassessment is essential as evolving signs often reveal the diagnosis
• Consider broader infectious workup if fever persists beyond 7 days without clear etiology