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Scarlet fever

Scarlet fever is a rash most commonly associated with bacterial pharyngitis in school age and adolescent
 children ( Salvatore Pardo , Thomas Perera 2019 )

Caused by Group A beta-hemolytic streptococcus Gram positive cocci that grow in chains
 Classified by their ability to
○ produce hemolysis on blood agar 
 ♦ alpha-hemolytic – partial hemolysis 
 ♦ beta-hemolytic -complete hemolysis 
 ♦ gamma-hemolytic – no hemolysis 

○ by differences in carbohydrate cell wall component
 ♦ A-H and K-T
 Sometimes also called scarlatina ( older literature ) Notifiable disease in UK  Prevalence-Predominantly childhood disease Children between age 2-8 yrs with peak at 4 yrs Rarely before 2 yrs ( maternal antibodies and lack of sensitization ) Seasonal ( spring and winter months in UK ) Highly contagious Outbreak in overcrowded situations ( eg schools , situational settings ) Transmission – via aerosol droplets and direct contact Incubation period 2-3 days ( but can range from 1-6 days )

pathophysiology-Toxin mediated disease Exotoxins from strains of Streptococcus pyogens also known as Group A Streptococcus (GAS )
 Local production of inflammatory mediators and alteration of the cutaneous cytokine milieu
○ inflammatory response and dilatation of blood vessels –> scarlet color of rash
 GAS- can be normal commensal of upper resp tract in 3-23 % of normal children
 When GAS causes infection- primary site is usually throat causing – sore throat

Investigations-Throat swab and culture
○ has 90 % sensitivity
○ less specific
 Anti-streptococcal antibody titre
 Antigen detection kits
○ eg Rapid antigen detection test
○ polymorphonuclear lymphocytosis is typical
○ eosinophilia may be seen during 2nd week

Presenting features-First features non specific
○ fever typically > 38.3
○ sore throat
○ headache , fatigue , nausea and vomiting
 Blanching rash –> develops an abdomen and chest 12-48 hrs after initial symptoms before spreading to neck , limbs and extremities
○ rash is diffuse , finely papular , erythematous
○ rash has red sandpaper like texture
○ florid in skin folds of neck , axillae , groin , elbows and knees
○ after 3-4 days rash begins to fade
○ skin may peel after rash resolves ( particularly tips of digits)
 Other possible features
○ strawberry tongue
 ♦ initially tongue covered with white coat through which papillae may be seen
 ♦ later white coat disappears leaving a beefy red tongue- strawberry or raspberry tongue
○ tender cervical lymphadenopathy
○ flushed face- circumoral pallor
○ pharyngitis- 
 ♦ red macules dotted over the hard and soft palate –> Forchheimer spots
 ♦ enlarged exudative tonsills
 Except for rash- symptoms similar as those of streptococcal pharyngitis

Differential-Rubella Parvovirus B19- Slapped cheek Measles Roseola infantum -Herpes virus type 6 Enterovirus and adenovirus Kawasaki disease Staphylococcal toxic shock syndrome

Rare causes
 Tropical viruses eg alphaviruses and flaviviruses ( Dengue fever ) Brucellosis , cytomegalovirus , HIV , syphillis , toxoplasmosis Drug reactions
Mononucleosis reaction to amoxicillin 
reaction to anti-epileptic drugs

Admission-Pre-existing valvular heart disease ↑ risk complications Immunocompromised ↑ risk complications Suspected severe complication of scarlet fever as
○ toxic shock syndrome
○ acute rheumatic fever
○ streptococcal glomerulonephritis

Treatment Phenoxymethylpenicillin ( Penicillin V ) 4/day for 10 days first line Amoxicillin is an alternative if for eg compliance is a concern Azithromycin for people allergic to penicillin
○ 12mg/ kg ( max 500 mg ) for childrem 6 mts to 11 yrs and 11 months
○ 500 mg if > 12 yrs and adults Paracetamol or Ibuprofen Rest and hydration Symptoms usually last no longer than 1 week Antibiotics will prevent complications Stay away from nursery , school or work for 24 hrs after starting antibiotic Hygiene measures and avoid sharing eating utensils and towels and dispose handkerchiefs properly Avoid contact with people with ↑ risk of complications of scarlet fever as
○ immunocompromized
○ skin lesions – as chicken pox or wounds
○ ♀ in puerperal period
○ comorbidities as diabetes Return if symptoms do not improve in after 7 days Beware of complications in 1st few weeks after infection
○ High risk contacts should seek urgent help if they develop any symptoms of GAS infection or its complications

Public health notification-Within 3 days Seek advice if a person is high risk contact- see above +
○ Injecting drug users
○ whether exclusions from work school or nursery and / or chemoprophylaxis

Complications-Suppurative –Due to spread to structures directly contagious to the pharynx -tend to occur early 
 Otitis media Throat infections and abscess
○ peritonsillar abscess
○ peritonsillar cellulitis
○ retropharyngeal abscess Acute sinusitis and mastoiditis Streptococcal pneumonia Meningitis and cerebral abscess Endocarditis , osteomyelitis and liver abscess Necrotizing fascitis and streptococcal toxic shock syndrome Non-suppurative-Tend to occur late and include
 Acute rheumatic fever
 Streptococcal glomerulonephritis
○ 2 weeks or more after infection
○ can present with
 ♦ haematuria
 ♦ ↓ urine output
 ♦ peripheral oedema
 ♦ proteinuria
 ♦ hypertension


  1. Merck manual Streptococcal Infections Larry M.Bush et al Practical Paediatrics Churchill Livingstone June 2012
  2. Easy Paediatrics Edited by Rachel Sidwell, Mike Thomson Hodder Education May 2011
  3. CKS NHS Scarlet fever
  4. Scarlet Fever Medscape Bahman Sotoodian et al March 2016
  5. Stanford T. Shulman, Alan L. Bisno, Herbert W. Clegg, Michael A. Gerber, Edward L. Kaplan, Grace Lee, Judith M. Martin, Chris Van Beneden, Clinical Practice Guideline for the Diagnosis and Management of Group A Streptococcal Pharyngitis: 2012 Update by the Infectious Diseases Society of America, Clinical Infectious Diseases, Volume 55, Issue 10, 15 November 2012, Pages e86–e102,
  6. Pelucchi, C., Grigoryan, L., Galeone, C., Esposito, S., Huovinen, P., Little, P., & Verheij, T. (2012). Guideline for the management of acute sore throat: ESCMID Sore Throat Guideline Group C. Pelucchi et al. Guideline for management of acute sore throat. Clinical Microbiology and Infection18(SUPPL.1), 1-28.

  7. Marshall, S. (2006) Scarlet fever: The disease in the UK.Pharmaceutical Journal 277(7410), 115-116.
  8. PHE Interim guidelines for the public health management of scarlet fever outbreaks in schools , nurseries and other childcare settings April 2014
  9. Health Protection Report: Group A streptococcal infections : sixth update on seasonal activity, 2014/15. Public Health England accessed via
  10. Scarlet fever : symptoms , diagnosis , treatment Public Health England
  11. Scarlet Fever Patient UK
  12. Mandell, Douglas and Bennett’s Principles and Practice of Infectious Diseases , Updated Edition



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