 Scarlet fever is an exotoxin-mediated disease that occurs most often in association with a sore throat and rarely with impetigo or other streptococcal infections. It is characterized by sore throat, fever, a 'strawberry' tongue, and a fine sandpaper rash over the upper body that may spread to cover almost the entire body. Scarlet fever is not rheumatic fever, but may progress into that condition as the infection develops (rheumatic fever is the autoimmune disease that occurs after infection with Group A strep).
Cause
Streptococcus pyogenes (group A strep) is responsible for scarlet fever. It can also cause simple angina, erysipelas and serious toxin mediated syndromes like necrotizing fasciitis and the so called streptococal toxic shock like syndrome. The virulence of group A strep seems to be increasing lately. The exanthem of scarlatina is thought to be due to erythrogenic toxin production by specific streptococcal strains in a nonimmune patient. Alongside with erythrogenic toxins, the Group A strep produces several toxins and enzymes. Two of the most important are the streptolysins O and S. Streptolysin O, an hemolytic, thermolabile and immunogenic toxin is the base of an assay for scarlatina and erysipelas - the anti-streptolysin O titer.
History
This disease was also once known as Scarlatina (from the Italian scarlattina). Many novels depicting life before the nineteenth century (see Scarlet fever in literature below) describe scarlet fever as an acute disease being followed by many months spent in convalescence. The convalescence was probably due to complications with rheumatic fever. Prior to an understanding of how streptococcus was spread, it was also not uncommon to destroy or burn the personal effects of a person afflicted with scarlet fever to prevent transmission to other people.
Signs and Symptoms
Early symptoms indicating the onset of scarlet fever can include:
- Fever of 38 to 40 degrees C (101-104 degrees F).
- Fatigue.
- Sore throat.
- Headache.
- Nausea or Vomiting.
- Abdominal pain.
- Flushed face with perioral pallor (circumoral pallor).
- Tachycardia (rapid pulse).
- Lymphadenopathy (enlarged lymph nodes).
- Punctate red macules on the hard and soft palate and uvula (ie, Forchheimer spots).
- Scarlet fever also produces a bright red tongue with a "strawberry" appearance.
- There is a characteristic rash which:
- is fine, red, and rough-textured; it blanches upon pressure.
- appears 12–48 hours after the fever.
- generally starts on the chest, axilla (armpits), and behind the ears.
- is worse in the skin folds.
- Pastia lines (where the rash becomes confluent in the arm pits and groins) appear and persist after the rash is gone.
- The rash begins to fade three to four days after onset and desquamation (peeling) begins. "This phase begins with flakes peeling from the face. Peeling from the palms and around the fingers occurs about a week later and can last up to a month." Peeling also occurs in axilla, groin, and tips of the fingers and toes.
Diagnosis of scarlet fever is clinical. The blood tests shows marked leukocytosis with neutrophilia and conservated or increased eosinophils, high ESR and CRP , and elevation of antistreptolysin O titer. Blood culture is rarely positive, but the streptococci can usually be demonstrated in throat culture. The complications of scarlet fever include septic complications due to spread of streptococcus in blood and immune mediated complications due to an aberrant immune response. Septic complications, today rare, include otitis, sinusitis, streptococcal pneumonia, empyema thoracis, meningitis and full blown septicaemia ( malignant scarlet fever) Immune complications include acute glomerulonephritis, rheumatic fever and erythema nodosum. The secondary scarlatinous disease ( or secondary malignant syndrome of scarlet fever) included renewed fever, renewed angina, septic ORL complications and nephritis or rheumatic fever and is seen around the 18th day of untreated scarlet fever.
Treatment
Other than the occurrence of the diarrhea, the treatment and course of scarlet fever are no different from those of any strep throat. In case of penicillin allergy, clindamycin or erythromycin can be used with success.
Antibiotic treatment is considered necessary to prevent rheumatic fever.
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