A healthy four year old male presents with 2 days of fever to 103.5F. He does not have any congestion, cough, vomiting or diarrhea. He feels a lot better after getting acetaminophen and ibuprofen. On day 3 of illness the following findings are seen. The rash is erythematous and rough to the touch. Surprisingly he states that his throat doesn’t hurt.
This is, of course, scarlet fever, a systemic infection caused by exotoxin producing strains of Streptococcus pyogenes (Group A Strep). Not all strains of GAS produce the toxin, only the obstreperous ones “lucky” enough to be infected with a toxin granting bacteriophage. It generally manifests in fever, sore throat and rash and is most common in children aged 4-8 years with a slight male predominance. It is rare after 10, since most patients have acquired an antibody to the exotoxin. The diagnosis is clinical but can be supported by rapid strep test and throat culture/confirmatory DNA assay. New super-accurate strep assays are becoming more readily available.
The main clinical manifestations are:
- Strawberry tongue
- Palatal petechiae, erythema and exudate
- Circumoral pallor
- A rash that is erythematous, blanching, fine and rough – sandpapery some might say!
- Appears within 3 days of onset of fever
- Starts centrally – especially the chest, armpits and behind the ears
- Circumoral pallor is common
- Prominent Pastia Lines in the intertriginous areas which can persist even after the main rash is gone
- The rash fades in 3-4 days followed by peeling
Treatment and Follow Up
Most children respond very well to treatment with pencillins (I’d advocate for amoxicillin in kids since it tastes better and is still dirt cheap). You can use clindamycin or erythromycin in penicillin allergic patients, though erythromycin resistant strains have been found in Hong Kong recently. Beginning in 2014, England saw a 50-year high in the number of cases due to new strains.
Complications include glomerulonephritis, rheumatic fever, erythema nodosum, otitis media, pneumonia, sepsis and more.
This Briefs post would not be possible without both my wife (the Pediatrician who made the diagnosis) and my four-year old son who had Scarlet Fever. I told her it was just the flu – she showed me the rash and dropped the mic…