scarlet fever

Last edited 12/2022 and last reviewed 02/2023

Scarlet fever results from an infection with Streptococcus pyogenes or group A beta haemolytic streptococci that produces an erythrogenic toxin (1,2).

Group A beta haemolytic streptococci is commonly found on the skin or in the throat and is responsible for causing bacterial sore throat or “strep throat” (1,2). It may also cause:

• impetigo
• bacteraemia
• necrotizing fasciitis
• streptococcal toxic shock syndrome (2).

Scarlet fever is primarily a childhood disease and is commonly seen in children between the ages of two and eight years (1).

It is a highly contagious infection. Transmission occurs when bacteria (present in an infected person’s saliva or mucous)

• is spread by aerosol - sneezing, coughing, or breathing out
• comes into direct contact with an uninfected person (1)

Although scarlet fever is seen after streptococcal sore throat in a majority of the patients, it may also occur following burns or an infected wound (2).

Invasive group A streptococcal disease and scarlet fever are notifiable disease under the Health Protection (Notification) Regulations 2010 (3).

This disease has an incubation period of two to four days (2).

Click here for an example image of scarlet fever rash

NHS England guidance notes (4):

• Scarlet fever remains a clinical diagnosis
  • first symptoms often include a sore throat, headache, fever, nausea and vomiting
• after 12 to 48 hours the characteristic fine red rash develops (if you touch it, it feels like sandpaper)
  • typically, it first appears on the chest and stomach, rapidly spreading to other parts of the body
  • on more darkly-pigmented skin, the rash may be harder to spot, although the 'sandpaper' feel should be present
• further symptoms include:
  • fever over 38.3º C (101º F) or higher is common
  • white coating on the tongue which peels a few days later, leaving the tongue looking red and swollen (known as 'strawberry tongue')
  • swollen glands in the neck
  • feeling tired and unwell
  • flushed red face, but pale around the mouth. The flushed face may appear more 'sunburnt' on darker skin
  • peeling skin on the fingertips, toes and groin area, as the rash fades
• the usual treatment for scarlet fever is a 10-day course of antibiotic, ideally phenoxymethylpenicillin
  • fever will usually subside within 24 hours of starting antibiotics

Reference:

• (1) Health Protection Agency (HPA) 2010. General information – Scarlet fever
• (2) Marshall S. Scarlet fever : the disease in the UK. The pharmaceutical journal 2006;277
• (3) Health Protection Agency (HPA) 2010. List of notifiable diseases
• (4) NHS England. Group A streptococcus communications to clinicians (December 2022).