Scarlet Fever

Scarlet fever is a nonsuppurative complication of group A streptococcal infection. While it usually occurs following a throat infection, a minority of cases result from a skin infection.

Presentation

Scarlet fever usually begins with fever, sore throat, and systemic symptoms (e.g., nausea, vomiting, malaise). The patient may also complain of headache, abdominal and myalgias. A characteristic rash with diffuse erythema and small papular elevations usually appears within 48 hours of illness onset. The patient may also develop a bright red tongue with prominent papillae (a.k.a., strawberry tongue). Resolution of the rash is followed by desquamation of the skin.

Pitfalls

• The strawberry tongue is NOT pathognomonic; it can occur in other conditions as well (e.g., Kawasaki disease, toxic shock syndrome, multisystem inflammatory syndrome in children).

Images from patients with scarlet fever

Rash characteristics

Diffuse erythema that blanches with pressure

Most marked in the skin folds, where Pastia lines (i.e., confluent petechia) may appear

Numerous small papular elevations give a sandpaper quality on palpation

Visually likened to a boiled lobtser or a bad sunburn

Circumoral pallor

​The palms and soles are usually spared

Evaluation

The diagnosis is made clinically. Microbiologic testing (e.g., throat culture, rapid antigen detection test) can confirm infection with group A streptococcus.

Management

Treatment is the same as for a streptococcal throat infection; antibiotics must target Streptococcus pyogenes. Twenty-four hours after the child begins taking antibiotics, they may return to school or daycare without posing a risk to the other children.

Pitfalls

• The rash does NOT need to be treated separately.

Recommended Reading

Streptococcal Pharyngitis

Video Lectures

References

1. Wessels MR. Pharyngitis and Scarlet Fever. 2016 Feb 10 [Updated 2016 Mar 25]. In: Ferretti JJ, Stevens DL, Fischetti VA, editors. Streptococcus pyogenes : Basic Biology to Clinical Manifestations [Internet]. Oklahoma City (OK): University of Oklahoma Health Sciences Center; 2016-. Available from: https://www.ncbi.nlm.nih.gov/sites/books/NBK333418

2. Basetti S, Hodgson J, Rawson TM, Majeed A. Scarlet fever: a guide for general practitioners. London J Prim Care (Abingdon). 2017;9(5):77-79. Published 2017 Aug 11. doi:10.1080/17571472.2017.1365677

3. Kliegman, Robert. Nelson Textbook of Pediatrics. Edition 21. Philadelphia, PA: Elsevier, 2020.

Streptococcal Pharyngitis

Presentation

The classic manifestation of streptococcal pharyngitis includes fever, sore throat, tonsillar exudates, and tender anterior cervical adenopathy. However, not all of these features may be present. Other common symptoms can include headache, nausea, vomiting, fatigue, myalgia, and abdominal pain. As well, physical examination may reveal palatal petechia or a scarlatiniform rash.

Incubation period: approximately 2 - 5 days

pitfalls

• Features of viral pharyngitis (e.g., cough, coryza, hoarseness, diarrhea) do NOT usually occur in patients with strep throat. However, the presence of a single viral feature does NOT rule out streptococcal pharyngitis.

• Frank tonsillar exudates are NOT pathognomonic of a streptococcal throat infection. Other pathologies (e.g., infectious mononucleosis, adenovirus pharyngitis) can also present with exudates.

• Children less than three years old do NOT usually present with classic symptoms but rather nonspecific manifestations such as rhinitis, low-grade fever, and decreased appetite.
  

Photos taken from individuals with streptococcal pharyngitis

Suggestive Features

Streptococcal Pharyngitis	Viral Pharyngitis
Exudative tonsillopharyngitis	Conjunctivitis
Tender anterior cervical adenopathy	Rhinorrhea ± nasal congestion
Fever	Cough
Scarlet fever (e.g., rash, strawberry tongue)	​Hoarseness
	Oropharyngeal vesicles or ulcers
	Diarrhea

Evaluation

Unfortunately, there isn't a combination of signs and symptoms that can preclude the need for microbiologic testing. When there is sufficient clinical suspicion of a streptococcal infection, the diagnosis should be confirmed with microbiologic testing (e.g., throat culture, rapid antigen detection test). In the pediatric age group, a negative rapid antigen detection test should be followed up with a culture. With few exceptions, a follow up culture is not necessary in adults.

pitfalls

• Clinical scoring systems (e.g., Centor criteria, McIssac) are neither sufficiently sensitive nor specific to establish a diagnosis. They cannot be used in placed of testing to determine the need for therapy.

• False-negative tests (both RADT and culture) can occur due to inadequate sampling.

• False-positive tests (both RADT and culture) can occur in individuals colonized with group A streptococcus.

Management

The recommended antibiotic therapy for treating streptococcal pharyngitis is a ten day course penicillin. Antibiotic treatment prevents the spread of infection and the development of complications. It is also important to recommend supportive measures. Recovery usually occurs within three to five days. Contagiousness decreases significantly 12 hours following the first dose of antibiotics.

pitfalls

• There is increasing resistance to macrolides (e.g., azithromycin).

• Eradication of S. pyogenes does not occur in a significant proportion of patients.

Common supportive measures

Maintaining adequate hydration

Analgesic/antipyretic therapy

Lozenges and throat drops

Rest

Soft foods (e.g., soup, smoothies, mashed potatoes)

Complications

Streptococcal pharyngitis can lead to further morbidity if the infection spreads or immunologic phenomena develop. The table below is not an all-inclusive list of suppurative and non-suppurative complications.

Suppurative	Nonsuppurative
Peritonsillar cellulitis/abscess	Acute rheumatic fever
Otitis media	Poststreptococcal glumerulonephritis
Sinusitis	Reactive arthritis
Bacteremia	Scarlet Fever
Meningitis	Streptococcal toxic shock syndrome
Impetigo/erysipelas
Necrotizing fasciitis

Video Lecture

References

1. Shulman ST, Bisno AL, Clegg HW, Gerber MA, Kaplan EL, Lee G, Martin JM, Van Beneden C; Infectious Diseases Society of America. Clinical practice guideline for the diagnosis and management of group A streptococcal pharyngitis: 2012 update by the Infectious Diseases Society of America. Clin Infect Dis. 2012 Nov 15;55(10):e86-102. doi: 10.1093/cid/cis629. Epub 2012 Sep 9. Erratum in: Clin Infect Dis. 2014 May;58(10):1496. Dosage error in article text. PMID: 22965026; PMCID: PMC7108032.

2. Shaikh N, Swaminathan N, Hooper EG. Accuracy and precision of the signs and symptoms of streptococcal pharyngitis in children: a systematic review. J Pediatr. 2012 Mar;160(3):487-493.e3. doi: 10.1016/j.jpeds.2011.09.011. Epub 2011 Nov 1. PMID: 22048053.

3. Woods WA, Carter CT, Schlager TA. Detection of group A streptococci in children under 3 years of age with pharyngitis. Pediatr Emerg Care. 1999 Oct;15(5):338-40. doi: 10.1097/00006565-199910000-00011. PMID: 10532665.

4. Webb KH, Needham CA, Kurtz SR. Use of a high-sensitivity rapid strep test without culture confirmation of negative results: 2 years' experience. J Fam Pract. 2000 Jan;49(1):34-8. Erratum in: J Fam Prac 2000 Apr;49(4):378. PMID: 10678338.

5. Spinks A, Glasziou PP, Del Mar CB. Antibiotics for sore throat. Cochrane Database Syst Rev. 2013 Nov 5;2013(11):CD000023. doi: 10.1002/14651858.CD000023.pub4. Update in: Cochrane Database Syst Rev. 2021 Dec 9;12:CD000023. PMID: 24190439; PMCID: PMC6457983.

Brain CT Quiz: Very High Difficulty