Scarlet Fever

Aetiology and epidemiology

Scarlet fever or scarlatina is an exotoxin-mediated disease arising from Group A beta-haemolytic streptococci (GABHS). Over one hundred different M protein types have been identified.

The organism is mainly spread by aerosol or droplet spread; although it can also be found in contaminated foods.

The incubation period for scarlet fever is usually 2-5 days. The infectivity period is about 5 days from when the patient is given antibiotics.

Clinical assessment

Scarlet fever usually begins with a sore throat, headache, fever, tender cervical lymphadenopathy and malaise. In children, abdominal pain may also occur. This is then followed by a confluent erythematous rash (A) with a sandpaper-like quality.

Other associated features include:

  • Strawberry tongue (B)
  • Pastias lines (C) in the flexural folds
  • Circumoral pallor
  • Pharyngitis
  • Desquamation of hands, feet and groin
Fig 1: Rash Fig 2: Strawberry tongue Fig 3: Pastias lines

Clinical presentations

A broad spectrum of clinical presentations associated with scarlet fever are listed in Table 1.

Table 1: Clinical presentations associated with scarlet fever
Impetigo and pyoderma Erysipelas Vaginitis
Bacteraemia Pneumonia Pericarditis
Septic arthritis Necrotising fasciitis Toxic shock syndrome


A variety of diagnostic tests for scarlet fever are available, see Table 2. There are, however, limitations associated with each investigation.

Table 2: Limitations associated with diagnostic tests for scarlet fever
Test Limitation
Streptococcal antibody test Streptococcal antibody tests are not indicated during acute illness but may confirm previous infection
Throat swab culture test Throat swab culture tests can be performed, but a good quality specimen is required. This is the gold standard test for scarlet fever but results can take 24-48 hours
Rapid diagnostic tests Rapid antigen testing is not routinely recommended for sore throats in the UK. The specificities are generally high but the sensitivities vary and depend on the quality of the throat swab specimen [6]


Scarlet fever is a notifiable disease and notification is required based on clinical suspicion.

Antibiotic treatment is indicated (penicillin V or erythromycin or cephalosporin) for 10 days.

Health Protection Agency guidance advises that children diagnosed with scarlet fever should be excluded from school for 5 days following the commencement of antibiotics.

The majority of texts advise 24 hours off school post-commencement of antibiotics for group A streptococcal pharyngotonsillitis alone.


Problems can arise from a range of complications associated with scarlet fever.

Table 3: Complications associated with scarlet fever
Peritonsillar abscess
Septic arthritis
Cerebral abscess
Toxic shock-like syndrome
Acute rheumatic fever

Note that the risks of post-streptococcal glomerulonephritis and acute rheumatic fever in the UK are low.