Scarlet Fever Severity: Complications, Mortality & Modern Outcomes

Scarlet fever (GAS pharyngitis + erythrogenic toxin) is now rarely fatal but carries serious complication risks.

Epidemiology

• Pre-antibiotic era: Mortality 15–20%; major cause of childhood death
• Current: Mortality <0.1% with antibiotics; ~1/1000 develop severe invasive disease

Major Complications

Suppurative (Local Spread)

• Peritonsillar abscess, cervical lymphadenitis, otitis media, sinusitis, mastoiditis

Non-Suppurative (Immune-Mediated)

• Acute Rheumatic Fever (ARF): 2–3 weeks post; Jones criteria (carditis, arthritis, chorea, erythema marginatum, subcutaneous nodules) → RHD
• Post-Streptococcal Glomerulonephritis (PSGN): 1–3 weeks; hematuria, hypertension, edema; usually self-limited
• PANDAS/PANS: Neuropsychiatric onset post-GAS

Invasive GAS (iGAS)

• Bacteremia, necrotizing fasciitis, streptococcal toxic shock syndrome (STSS)
• Mortality 10–30% despite ICU care

Treatment & Prevention

• Penicillin/amoxicillin 10 days (eradicate carriage, prevent ARF)
• Azithromycin/clarithromycin if allergic (resistance emerging)
• Exclude from school 24h after antibiotic start
• No vaccine; GAS vaccine candidates in development

Prompt antibiotic treatment transforms a potentially devastating illness into a manageable one.