Scarlet fever

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).

A milder form of scarlet fever is described by some clinicians as “scarlatina” although others consider this to be a synonym for scarlet fever (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).