9.19. Scarlet Fever

Scarlet Fever Fact Sheet for Healthcare Professionals

This guidance is intended to raise awareness among healthcare workers, leading to timely diagnosis and management of patients, staff, and visitors who present with symptoms suggestive of scarlet fever. This is necessary to prevent and control the spread of infectious diseases and avert outbreaks.

Disease Description

Scarlet fever is caused by infection with Group A Streptococcus (GAS), a group of Gram-positive bacteria that can be carried in the throats or on the skin of humans. GAS infection frequently causes mild illnesses such as tonsillitis, pharyngitis, impetigo, cellulitis, and scarlet fever, predominantly in school-aged children, although anyone can become infected. Only a small proportion of people infected with GAS will develop scarlet fever.

Modes of Transmission

• Droplet or airborne transmission: via droplets produced by coughing or sneezing.
• Direct contact: through direct contact with a wound of an infected individual.
• Indirect contact: by freshly contaminated fomites.

Incubation Period

It usually takes 2 to 5 days for someone exposed to the bacteria to begin experiencing signs and symptoms.

Period of Communicability (Infectious Period)

• A person with scarlet fever is contagious from the onset of symptoms until 24 hours after beginning appropriate antibiotic therapy.
• Without antibiotic treatment, an individual may remain contagious for 10–21 days from onset of symptoms.
• Individuals with untreated streptococcal pharyngitis may continue to spread the bacteria for up to 3 weeks.
• A person is considered non-infectious after 24 hours of appropriate antibiotic treatment and once they are afebrile. They may return to school or work at that point.

Clinical Presentation

The clinical presentation of scarlet fever may be very similar to other infections and may include:

General Symptoms

• Fever (38.3°C / 101°F or higher).
• Chills.
• Headache or body aches.
• Nausea or vomiting.
• Sore throat and pain when swallowing.
• Stomach pain.

Skin

• A rash usually appears 1–2 days after the onset of symptoms; however, on occasion it may appear before illness or up to 7 days later.
• The rash may first appear on the neck, underarm, and groin, then spreads to the entire body.
• It usually begins as small, flat erythematous blotches that blanch on pressure. They slowly become fine bumps that feel like sandpaper and appear a deeper red in skin creases (Pastia's lines).
• The cheeks may appear flushed with a pale area around the mouth (circumoral pallor).
• The rash usually spares the palms and soles.
• Desquamation (peeling) of the skin occurs as the rash fades, typically 7 days after its appearance.

Neck and Oral Cavity

• Early in illness: whitish coating on the tongue.
• Later in illness: “strawberry tongue” — red and bumpy appearance.
• Enlarged, red tonsils with white patches or purulent discharge.
• Tiny red spots (petechiae) on the roof of the mouth (palate).

Complications

Complications are uncommon and occur if the bacteria spread to other parts of the body:

• Abscesses around the tonsils (peritonsillar abscess).
• Arthritis.
• Ear, sinus, and skin infections.
• Pneumonia.
• Post-streptococcal glomerulonephritis (a kidney disease).
• Rheumatic fever (affecting the heart, joints, brain, and skin).
• Swollen lymph nodes in the neck.

Diagnosis and Management

Diagnosis is based on clinical presentation and confirmed by laboratory identification of the bacteria.

Specimen Collection and Diagnostic Testing

Reporting

Treatment

• GAS infections are easily treated with antibiotics, and a person with a mild illness stops being contagious after 24 hours of treatment.
• Penicillin or amoxicillin is the antibiotic of choice to treat scarlet fever.
• A cephalosporin can be used for individuals with allergies to penicillin.

Isolation and Exclusion

• Cases should be excluded from school, childcare, and work settings until they have completed at least 24 hours of antibiotic therapy and are afebrile.
• Household contacts do not routinely require prophylactic antibiotics unless they are at high risk, such as those with a history of rheumatic fever or those who are immunocompromised.
• Healthcare workers with scarlet fever should be excluded from patient care until 24 hours after initiating antibiotic therapy.

Key Messages for Healthcare Workers

• Maintain clinical suspicion for scarlet fever in any school-aged child presenting with fever, sore throat, and rash.
• Collect a throat swab before initiating antibiotic therapy.
• Ensure a full 10-day antibiotic course is prescribed and explained to patients/caregivers to prevent complications.
• Report all suspected and confirmed cases to the Epidemiology Unit.
• Advise exclusion from school and work for 24 hours after starting antibiotics and once fever-free.

Reference List

• Centers for Disease Control and Prevention (2024). Scarlet Fever: A Group A Streptococcal Infection. Available from: https://www.cdc.gov/groupastrep/diseases-public/scarlet-fever.html
• World Health Organization (2023). Group A Streptococcal Disease. Available from: https://www.who.int/news-room/fact-sheets/detail/streptococcal-group-a
• Public Health England (2022). Scarlet Fever: Guidance, Data and Analysis. UK Health Security Agency.
• Shulman S.T. et al. (2012). Clinical Practice Guideline for the Diagnosis and Management of Group A Streptococcal Pharyngitis: 2012 Update by the IDSA. Clinical Infectious Diseases, 55(10), e86–e102.