Scarlet Fever

Scarlet Fever: Excerpt from The 5-Minute Pediatric Consult

Mark L. Bagarazzi, MD

Scarlet Fever - BASICS

Scarlet Fever - description

• A clinical syndrome consisting of fever, pharyngitis, cervical lymphadenitis, and the characteristic “sandpaper rash,” which results from infection with a strain of Streptococcus pyogenes (group A β-hemolytic streptococcus) that elaborates streptococcal pyrogenic toxin
• Toxins include A, B, and C. Toxin A is associated with more virulent disease.
• Similar syndrome may also be seen after infection with certain toxin-producing (enterotoxin G, I) strains of Staphylococcus aureus; known as staphylococcal scarlet fever.

Scarlet Fever - general prevention

• Prompt treatment leads to fewer secondary cases of streptococcal disease.
• Chemoprophylaxis with penicillin is recommended by some experts in children with repeated documented episodes occurring at short intervals.

Scarlet Fever - epidemiology

• No sex predilection
• Occurs uncommonly before the age of 3 years or after the age of 15 years, possibly related to the requirement for prior sensitization and toxin-specific immunity
• All forms of streptococcal pharyngitis (i.e., with or without pyrogenic toxin) are more common in temperate and cold climates and winter and spring months, with some areas reporting an increased incidence in the fall.
• Incubation period is usually 24–48 hours.

Scarlet Fever - incidence

Peak incidence during the 1st few school years

Scarlet Fever - prevalence

By age 10, 80% of children have developed toxin-specific antibodies.

Scarlet Fever - pathophysiology

• Susceptible individuals are thought to lack toxin-specific immunity (supported by results of Dick test, in which a small amount of toxin introduced intradermally produces local erythema in susceptible individuals but no reaction in those with toxin-specific immunity).
• Rash and other toxic manifestations of scarlet fever have been attributed to the development of hypersensitivity to the toxin, which therefore would require prior exposure to the toxin.
• Toxin production depends on lysogeny of the infecting streptococcus by a temperate bacteriophage.
• Pharyngitis is characterized by mucosal erythema and frequently by small crypt abscesses with punctate exudate in enlarged tonsils.
• Edematous papillae protrude from coated mucosa to produce a strawberry tongue.
• Histologic examination of affected skin shows dilated blood and lymphatic vessels and engorged capillaries, most prominently around hair follicles.
• Acute, edematous polymorphonuclear inflammatory reaction is seen microscopically within affected tissues.
• Epidermal inflammatory reaction is usually followed by hyperkeratosis, which accounts for scaling during defervescence.

Scarlet Fever - DIAGNOSIS

Scarlet Fever - signs & symptoms

Scarlet Fever - history

• Sudden onset of fever up to 40.5°C, sore throat, headache, nausea, vomiting, and toxicity are classic symptoms for group A streptococcal disease.
• Texture of rash (e.g., feels like sandpaper) is more important than appearance.
• Characteristic rash typically occurs 12–48 hours after onset of fever.
• Patient may complain of abdominal pain or muscle aches before onset of rash, as well as aching in extremities or back.
• There may be close contacts with streptococcal infection.

Scarlet Fever - physical exam

• Fine maculopapular (sandpaper texture) rash on erythematous background:
  • Usually begins on the trunk and spreads to involve almost the entire body within hours to days.
  • Although the rash seen with scarlet fever is generally fine and sandpaperlike, larger papules and petechiae may be seen.
• Deep, red, nonblanching lesions in the antecubital and popliteal areas:
• “Pastia lines” develop in the skin folds of joints.
• Circumoral pallor: Classic finding
• Rash blanches with pressure and ultimately desquamates:
  • Desquamation occurs within 7–21 days from onset of illness.
• Characteristic toxin-induced scarlet fever exanthem: May rarely be seen without pharyngitis in the setting of pyoderma or an infected wound (known as surgical scarlet fever)
• Systemic toxicity: May indicate incorrect diagnosis
• Dorsum of tongue: Has white coat early in illness with edematous red papillae. White covering desquamates and reveals swollen, red, and mottled strawberry tongue.
• Other findings:
  • Pharynx and tonsils are beefy red and may contain exudate.
  • Hemorrhagic spots on interior pillar of tonsils and soft palate
  • Large, tender anterior cervical nodes

Scarlet Fever - tests

Scarlet Fever - lab

• Rapid streptococcal antigen tests: Effective as screening tests; 50–80% sensitivity and >95% specificity. Positive rapid tests do not require culture confirmation.
• Throat culture: The gold standard with best sensitivity (>90%) for group A β-hemolytic streptococci. A culture should be performed when rapid test is negative.
• White blood cell count: Usually elevated, although may be elevated in viral pharyngitis as well. Low count would be rare with streptococcal infection.
• Eosinophilia (up to 30%): Common in the recovery phase
• Dick test: Of historic interest; no longer used clinically

• A positive throat culture may be evidence only of carriage in some cases of acute pharyngitis that are actually viral (e.g., Epstein–Barr virus).
• Milder disease is becoming more common and is easier to miss.
  • Rash may involve only the bridge of the nose, face, shoulders, and upper chest.
  • Circumoral pallor and severe exudative pharyngitis are being seen less frequently.

Scarlet Fever - differencial diagnosis

• Nonscarlatinal streptococcal pharyngitis/tonsillitis
• Viral exanthems (measles, rubella, erythema infectiosum)
• Drug eruptions
• Staphylococcal scalded skin syndrome
• Toxic epidermal necrolysis
• Toxic shock syndrome (streptococcal or staphylococcal)
• Kawasaki disease
• Uncommon entities:
  • Infection with Corynebacterium hemolyticum
  • Mercury poisoning (acrodynia)
  • Atropine intoxication
  • Boric acid poisoning
  • Rifampin overdose

Scarlet Fever - TREATMENT

Scarlet Fever - initial stabilization

• Identical to therapy for streptococcal pharyngitis
• Therapy started as late as 9 days after illness onset should be effective in preventing acute rheumatic fever.
• May withhold treatment until throat culture result is available
• Immediate therapy probably shortens symptomatic period.

Scarlet Fever - medication

• Oral penicillin VK:
  • Drug of choice except in penicillin-allergic individuals
  • Resistant strains have not been documented in the United States.
  • Dose: 25,000–50,000 U/kg (1,600 U = 1 mg) divided into 3–4 doses for 10 days
  • 400,000 units (250 mg) b.i.d. for 10 days has also been shown to have comparable efficacy and is endorsed by the American Academy of Pediatrics.
• Intramuscular benzathine penicillin G:
  • Equally effective as oral penicillin
  • Dose: 600,000 U for children <60 pounds; 1,200,000 U in larger children and adults
  • Ensures compliance
  • Bringing to room temperature reduces discomfort.
  • Benzathine/Procaine penicillin combinations are less painful.
• Clarithromycin and azithromycin have also been shown to eradicate streptococci; however, because of the broad spectra of these antibiotics and the increasing incidence of antibiotic-resistant bacteria, penicillin is still recommended by most experts, except in cases of penicillin hypersensitivity, when patient nonadherence to a 10-day penicillin regimen is suspected, or for patients who fail therapy with a β-lactam:
  • Azithromycin, total dose of 60 mg/kg, given either as 12 mg/kg once daily for 5 days or 20 mg/kg once daily for 3 days
  • Clarithromycin, 15 mg/kg/d, given q12h for 10 days, or 500 mg extended-release tablets given once a day for 5 days (studied in adolescents ≥12 years)
  • There are reports of acute rheumatic fever after the 3-day course of azithromycin.
• Oral erythromycin is indicated in penicillin-allergic individuals. Erythromycin ethyl succinate (40–50 mg/kg/d in 2–4 divided doses). Resistance is rare in the US (<5% of isolates).
• Amoxicillin, clindamycin, and first-generation oral cephalosporins (up to 15% of penicillin-allergic persons are also allergic to cephalosporins) are reasonable alternatives to penicillin.
• Recent trials comparing 10-day course of penicillin with shorter duration of therapy with newer oral cephalosporins have shown similar bacteriologic and clinical cure rates, but efficacy in prevention of nonsuppurative sequelae is unknown.
• Cefdinir and cefpodoxime proxetil are approved for use in a more convenient 5-day dosing schedule.
• Tetracyclines and sulfonamides should not be used because of resistance of group A streptococci.
• Positive posttreatment cultures in asymptomatic patients: Retreatment is not recommended.

Scarlet Fever - FOLLOW UP

• Fever and symptoms usually resolve within 24–48 hours of antibiotic treatment.
• Nonsuppurative complications occur after unrecognized disease and when treatment is delayed for >9 days. Acute rheumatic fever occurs an average of 18 days after untreated infection. Acute postinfectious glomerulonephritis occurs an average of 10 days after untreated infection.

Scarlet Fever - prognosis

• Overall prognosis is excellent.
• Few patients suffer suppurative complications.
• Risk of developing acute rheumatic fever in untreated streptococcal infections is ~3% under epidemic conditions (0.3% in endemic situations).
• Risk of developing acute postinfectious glomerulonephritis depends on nephritogenicity of infecting strain. Attack rate is 10–15% with nephritogenic strains.

Scarlet Fever - complications

• Acute otitis media
• Sinusitis
• Suppurative cervical lymphadenitis
• Pneumonia with or without effusion/empyema
• Peritonsillar cellulitis/abscess
• Retropharyngeal abscess
• Meningitis
• Brain abscess
• Thrombosis of intracranial venous sinuses
• Osteomyelitis
• Hepatitis
• Arthritis
• Acute rheumatic fever
• Acute postinfectious glomerulonephritis
• Erythema nodosum, possibly

Scarlet Fever - bibliography

1. Altemeier WA. A pediatrician’s view. A brief history of group A beta hemolytic strep. Pediatr Ann. 1998;27:264–267.
American Academy of Pediatrics. Group A streptococcal infections. In: Pickering LK, ed. Red Book 2006: Report of the Committee on Infectious Diseases. 27th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2006:610–620.
2. Barnett BO, Frieden IJ. Streptococcal skin diseases in children. Semin Dermatol. 1992;11:3–10.
3. Breese BB. Streptococcal pharyngitis and scarlet fever. Am J Dis Child. 1978;132:612–616.
4. Duncan SR, Scott S, Duncan CJ. Modeling the dynamics of scarlet fever epidemics in the 19th century. Eur J Epidemiol. 2000;16:619–626.
5. Jarraud S, Cozon G, Vandenesch F, et al. Involvement of enterotoxins G and I in staphylococcal toxic shock syndrome and staphylococcal scarlet fever. J Clin Microbiol. 1999;37:2446–2449.
6. Richardson M, Elliman D, Maguire H, et al. Evidence base of incubation periods, periods of infectiousness and exclusion policies for the control of communicable diseases in schools and preschools. Pediatr Infect Dis J. 2001;20:380–391.
7. Shiseki M, Miwa K, Nemoto Y, et al. Comparison of pathogenic factors expressed by group A streptococci isolated from patients with streptococcal toxic shock syndrome and scarlet fever. Microb Pathog. 1999;27:243–252.

Scarlet Fever - CODES

Scarlet Fever - icd9

034.1 Scarlatina

Scarlet Fever - FAQ

• Q: Should household contacts have throat cultures performed?
• A: Obtain cultures only from symptomatic household contacts. Cultures should not routinely be obtained in asymptomatic contacts.
• Q: Should posttreatment throat cultures be performed?
• A: Only in symptomatic individuals and patients at risk for acute rheumatic fever and acute postinfectious glomerulonephritis
• Q: Can scarlet fever recur?
• A: Yes, there have been documented reports of recurrent scarlet fever.
• Q: Have there been documented day care outbreaks of scarlet fever?
• A: Yes, outbreaks have been traced back to a single strain.
• Q: How soon can children return to school or day care?
• A: When they are afebrile, and after at least 24 hours of antibiotic therapy.

Book Source Details

• Book Title: The 5-Minute Pediatric Consult
• Author(s): M. William Schwartz MD; et al.
• Year of Publication: 2008
• Copyright Details: The 5-Minute Pediatric Consult, Copyright © 2008 Lippincott Williams & Wilkins.

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More About This Book: Title: The 5-Minute Pediatric Consult Authors: M. William Schwartz MD; et al. Publisher: Lippincott Williams & Wilkins Copyright: 2008 ISBN: 0-7817-7577-9

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