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Scarlet fever

Last updated: November 3, 2020

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Scarlet fever is a syndrome caused by infection with toxin-producing group A β‑hemolytic streptococci (Streptococcus pyogenes, GAS) and primarily affects children between the ages of five and fifteen. The syndrome occurs in less than 10% of cases of streptococcal tonsillopharyngitis and classically presents with fever, pharyngeal erythema with tonsillar exudates, and a fine, scarlet-colored rash that is most pronounced in the groin, underarm, and elbow creases. After approximately a week, the skin begins to desquamate on the face, trunk, hands, fingers, and toes. Antibiotic treatment with penicillin is recommended, as scarlet fever may progress to severe disease and other complications associated with Streptococcus infection (e.g., rheumatic fever and post‑streptococcal glomerulonephritis). Scarlet fever is caused by various types of erythrogenic scarlet fever toxins, secreted by S. pyogenes and as such, recurrent infection with other types of toxins is possible.

  • Peak incidence: 5–15 years (although it may affect individuals of any age) [1]
  • Generally occurs in association with streptococcal cases of tonsillopharyngitis

Epidemiological data refers to the US, unless otherwise specified.

References:[2]

Incubation period

  • 2–5 days [1]

Initial phase (acute tonsillitis)

Exanthem phase

  • Rash appears 12–48 hours after the onset of fever. [3]

Scarlet‑colored maculopapular exanthem (rash)

  • Presentation
    • Fine, erythematous, sandpaper‑like texture
    • Blanches with pressure
    • Nonblanching petechiae are often additionally present
    • May be pruritic
    • Pastia lines
      • A key sign of scarlet fever: linear, petechial appearance
      • Most pronounced in the groin, underarm, and elbow creases (i.e., flexural areas)
  • Location
    • Begins on the neck
    • Disseminates to the trunk and extremities
  • Duration: ∼ 7 days [4]

The characteristic scarlet fever rash is said to resemble goosebumps with a sunburn.

Tonsillopharyngitis

Desquamation phase

  • Appears 7–10 days after resolution of rash [4]
  • Skin desquamation: desquamation of the skin in flakes
  • Affects face, trunk, hands, fingers, and toes

Findings like coryza, rhinorrhea, cough, hoarseness, anterior stomatitis, conjunctivitis, and ulcerative lesions are atypical for scarlet fever and warrant further investigation.

Scarlet fever is primarily a clinical diagnosis that should be confirmed with additional testing.

The differential diagnoses listed here are not exhaustive.

The aim of antibiotic treatment is to prevent complications and shorten the period of infectivity.

Scarlet fever is considered one of the nonsuppurative (i.e., non-pus forming) complications of streptococcal tonsillopharyngitis. Other complications of GAS infection may also occur during or following scarlet fever, especially in patients who did not receive antibiotic treatment.

Nonsuppurative

Suppurative (i.e., pus-forming)

We list the most important complications. The selection is not exhaustive.

  1. Group A Streptococcal (GAS) Disease - Scarlet Fever. https://www.cdc.gov/groupastrep/diseases-hcp/scarlet-fever.html. Updated: January 17, 2017. Accessed: March 19, 2017.
  2. Forbish Skipwith D, Kelly Freeman M. Scarlet fever. US Pharm. 2008; 33 (3): p.48-58.
  3. Kliegman R, Behrman RE, Jenson HB. Nelson Textbook of Pediatrics. W B Saunders Company ; 2007
  4. Basetti S, Hodgson J, Rawson TM, Majeed A. Scarlet fever: a guide for general practitioners.. London journal of primary care. 2017; 9 (5): p.77-79. doi: 10.1080/17571472.2017.1365677 . | Open in Read by QxMD
  5. Wang K, Lee J. Rumpel–Leede Sign. N Engl J Med. 2014; 370 . doi: 10.1056/NEJMicm1305270 . | Open in Read by QxMD
  6. Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections (PANDAS). https://www.ncbi.nlm.nih.gov/books/NBK333424/. Updated: January 1, 2016. Accessed: October 28, 2020.
  7. Cunningham MW. Molecular Mimicry, Autoimmunity, and Infection: The Cross-Reactive Antigens of Group A Streptococci and their Sequelae. Microbiol Spectr. 2019; 7 (4). doi: 10.1128/microbiolspec.gpp3-0045-2018 . | Open in Read by QxMD
  8. PANDAS Diagnostic Guidelines. https://www.pandasppn.org/what-are-pans-pandas/. Updated: January 1, 2020. Accessed: October 28, 2020.
  9. Parvovirus B19 and Fifth Disease - Fifth Disease. https://www.cdc.gov/parvovirusb19/fifth-disease.html. Updated: November 2, 2015. Accessed: March 19, 2017.
  10. Khan ZZ. Group A Streptococcal Infections. Group A Streptococcal Infections. New York, NY: WebMD. http://emedicine.medscape.com/article/228936-overview. Updated: November 3, 2016. Accessed: March 19, 2017.
  11. Pichichero ME. Complications of streptococcal tonsillopharyngitis. In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/complications-of-streptococcal-tonsillopharyngitis?source=search_result&search=scarlet+fever&selectedTitle=1~25.Last updated: February 4, 2016. Accessed: March 19, 2017.
  12. UpToDate. Patient education: Scarlet fever (The Basics). In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/scarlet-fever-the-basics?source=see_link.Last updated: March 19, 2017. Accessed: March 19, 2017.