Scarlet Fever
Basics
Description
- A disease (typically in childhood) characterized by fever, pharyngitis, and rash caused by group A β-hemolytic Streptococcus pyogenes (GAS) that produces erythrogenic toxin
- Incubation period: 1 to 7 days
- Duration of illness: 4 to 10 days
- Rash (erythematous, blanchable 1 to 2 mm papules; “sand paper”) usually appears within 24 to 48 hours after symptom onset.
- Rash first appears in the groin, trunk, and axillae accompanied by strawberry tongue and circumoral pallor and then rapidly spreads outward all over the body, sparing palms and soles.
- Rash clears at the end of the 1st week and is followed by several weeks of desquamation.
- Rash is not dangerous but is a marker for GAS infection with suppurative and nonsuppurative complications.
- System(s) affected: head, eyes, ears, nose, throat, skin/exocrine
- Synonym(s): scarlatina
Epidemiology
Incidence
- In developed countries, 15% of school-aged children and 4–10% of adults have an episode of GAS pharyngitis each year.
- Scarlet fever is rare in infancy because of maternal antitoxin antibodies.
- Predominant age: 6 to 12 years
- Peak age: 4 to 8 years
- Predominant sex: male = female
- Rare in the United States in persons aged >12 years because of high rates (>80%) of lifelong protective antibodies to erythrogenic toxins
Prevalence
- 15–30% of cases of pharyngitis in children are due to GAS; 5–15% in adults
- <10% of children with streptococcal pharyngitis develop scarlet fever.
Etiology and Pathophysiology
- Erythrogenic toxin production is necessary for scarlet fever to develop clinically.
- Three toxin types: A, B, C
- Toxins damage capillaries (producing rash) and act as superantigens, stimulating cytokine release.
- Antibodies to toxins prevent development of rash but do not protect against underlying infection.
- Primary site of streptococcal infection is usually within the tonsils, but scarlet fever may also occur with infection of skin, surgical wounds, or uterus (puerperal scarlet fever).
Risk Factors
- Winter/early spring seasonal increase
- More common in school-aged children
- Contact with infected individual(s)
- Crowded living conditions (e.g., lower socioeconomic status, barracks, child care, schools)
General Prevention
- Spread by contact with airborne respiratory droplets, saliva, and nasal secretions
- Foodborne outbreaks have been reported but are rare.
- Asymptomatic contacts do not require cultures/prophylaxis.
- Symptomatic contacts of a child with documented GAS infection who have recent or current clinical evidence of a GAS infection should undergo appropriate laboratory tests and should be treated if test results are positive.
- Children should not return to school/daycare until they are afebrile and have received 24 hours of antibiotic therapy.
Commonly Associated Conditions
- Pharyngitis
- Impetigo
- Rheumatic fever
- Glomerulonephritis
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Citation
Domino, Frank J., et al., editors. "Scarlet Fever." 5-Minute Clinical Consult, 33rd ed., Wolters Kluwer, 2025. Medicine Central, im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117669/all/Scarlet_Fever.
Scarlet Fever. In: Domino FJF, Baldor RAR, Golding JJ, et al, eds. 5-Minute Clinical Consult. Wolters Kluwer; 2025. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117669/all/Scarlet_Fever. Accessed December 3, 2024.
Scarlet Fever. (2025). In Domino, F. J., Baldor, R. A., Golding, J., & Stephens, M. B. (Eds.), 5-Minute Clinical Consult (33rd ed.). Wolters Kluwer. https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117669/all/Scarlet_Fever
Scarlet Fever [Internet]. In: Domino FJF, Baldor RAR, Golding JJ, Stephens MBM, editors. 5-Minute Clinical Consult. Wolters Kluwer; 2025. [cited 2024 December 03]. Available from: https://im.unboundmedicine.com/medicine/view/5-Minute-Clinical-Consult/117669/all/Scarlet_Fever.
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