- Clinical science
Scarlet fever is a syndrome caused by infection with toxin-producing group A β‑hemolytic streptococci (Streptococcus pyogenes) 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 the 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)
- Occurs in < 10% of streptococcal cases of tonsillopharyngitis
Epidemiological data refers to the US, unless otherwise specified.
- Route of transmission: aerosol
- 1–7 days
Initial phase ()
- Malaise, headache, chills, and myalgias
- Sore throat and difficulty swallowing
- White coating on the tongue
- Enlarged cervical lymph nodes
Gastrointestinal symptoms (possible in young children)
- Abdominal pain
- Nausea and vomiting
- Rarely scarlet fever develops following a streptococcal soft‑tissue infection, rather than tonsillitis.
- Rash appears 12–48 hours after the onset of fever.
Scarlet‑colored maculopapular exanthem (rash)
- Begins on the neck
- Disseminates to the trunk and extremities within 24 hours
- ∼ 7 days
- Pharyngeal erythema; , possibly with tonsillar exudates
- Strawberry tongue: bright red tongue color with papillary hyperplasia, which is revealed once the white coating has sloughed off
- Typical red, flushed appearance of the cheeks with perioral pallor
- Appears 7–10 days after resolution of rash
- Desquamation of the skin in flakes
- Affects face, trunk, hands, fingers, and toes
Findings atypical of scarlet fever include coryza, rhinorrhea, cough, hoarseness, anterior stomatitis, conjunctivitis, and ulcerative lesions on the mucous membranes; these findings warrant further investigation!
- Primarily a clinical diagnosis that should be confirmed with additional testing
- Throat culture
- Rapid antigen detection testing (rapid strep test)
Blood and urine studies
- Complete blood cell (CBC) count shows leukocytosis with a left shift; possibly eosinophilia over the course of disease
- Urinalysis and liver function tests may indicate complications of scarlet fever (see “Complications” below).
- ↑ Inflammatory markers: C-reactive protein (CRP), erythrocyte sedimentation rate (ESR)
- Other tests
- Indication: All cases of scarlet fever should be treated with antibiotics, both to prevent complications and to prevent transmission
- Drug of choice: oral penicillin V
- Alternative antibiotics
- After 24 hours of antibiotic treatment, the patient is no longer infectious and may return to day care or school!
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.
- Suppurative (i.e., pus-forming)
We list the most important complications. The selection is not exhaustive.