Scarlet fever manifests as diffuse blanching “sandpaper-like” erythematous macules and papules caused by erythrogenic toxin production from group A β-hemolytic Streptococcus pharyngitis. Occasionally, the site of infection is skin (impetigo) or perianal. The disease usually occurs in children 2 to 10 years of age. The typical presentation of scarlet fever includes fever, headache, sore throat, nausea, vomiting, and malaise followed by the characteristic scarlatiniform rash. The rash initially occurs on the groin and trunk, spreading to the face (often with perioral sparing) and neck, then quickly becomes generalized. Desquamation occurs after 5 to 7 days. On the tongue, a thick, white coat and swollen papillae may be seen (“strawberry tongue”). Palatal petechiae and tender anterior cervical lymphadenopathy may be present. The gold standard for diagnosis is a positive throat culture of a swab from the tonsillar pillars, though rapid antigen testing is highly specific and can provide prompt diagnosis. The differential diagnosis includes enteroviral infections, staphylococcal scalded skin syndrome, viral hepatitis, infectious mononucleosis, toxic shock syndrome, drug eruptions, rubella, mercury poisoning, and Kawasaki disease.
Management and Disposition
Penicillin, either a single intramuscular dose of benzathine penicillin G or oral amoxicillin for 10 days, is the treatment of choice. Alternatives include erythromycin or clindamycin in penicillin-allergic patients.
In scarlet fever, petechiae in a linear pattern along the major skin folds in the axillae and antecubital fossae are known as “Pastia lines.”
In dark-skinned individuals, the rash may be difficult to differentiate and may consist only of punctate papular elevations called “goose flesh.”
There has never been an isolate of group A Streptococcus that is resistant to penicillin.
Scarlatina is a rash that spares the palms and soles, although desquamation can occur in those areas.
Scarlatina. Erythematous scarlatiniform rash of scarlet fever. (Photo contributor: Lawrence B. Stack, MD.)
Goose Flesh. This sandpaper rash started 2 days after sore throat and fever began in this 6-year-old. The grouping of the fine papules gives the skin a “goose flesh” texture in darker skin colors. (Photo contributor: Lawrence B. Stack, MD.)
Palatal Petechiae. Petechiae present on the posterior soft palate of a child with group A streptococcal infection. (Photo contributor: Hannah F. Smitherman, MD.)
Pastia Lines. Confluent petechiae in a linear pattern in the antecubital fossa consistent with Pastia lines are seen in these patients with scarlet fever. (A) The forearm on the right belongs to the patient’s sister and does not show Pastia lines. (B) Pastia lines in a Caucasian patient. A classic sandpaper rash is also evident on the arm and trunk. (Photo ...