Scarlet fever

Disease Description (Causes and Symptoms)

Scarlet fever is caused by infection with Group A beta-hemolytic Streptococcus (Group A Streptococcus, GAS). Generalized rash and characteristic symptoms develop due to the hemolytic and rash-inducing toxins (erythrogenic/pyrogenic exotoxin) secreted by GAS. The main features are acute fever, sore throat and tonsillitis, enlargement of the lymph nodes in the neck, and a fine papular (millet-sized) rash and “strawberry tongue (white → red strawberry tongue).” The rash spreads over the body except around the mouth (circumoral pallor), and peeling of the skin on the hands and feet is common during recovery. The incubation period is usually 2–7 days.

Main Symptoms

• High fever (around 39°C), chills
• Sore throat, enlarged and reddened tonsils
• Loss of appetite, vomiting, generalized malaise
• Fine generalized rash (sandpaper-like texture, possibly itchy), facial flushing and pallor around the mouth
• Strawberry tongue: initial coating (white strawberry tongue) → prominent bright-red papillae (red strawberry tongue) after 2–3 days
• Enlarged, painful cervical lymph nodes

Complications include otitis media, sinusitis, pneumonia, abscesses (peritonsillar or cervical), acute glomerulonephritis, and rheumatic fever. Some complications may develop through immune-mediated mechanisms within several weeks after the infection.

Treatment Methods

1. Antibiotic treatment (standard)

   • First-line: penicillin-based drugs (oral penicillin V for 10 days or a single intramuscular injection of benzathine penicillin G) — highly effective against GAS and intended to prevent rheumatic fever and other complications.
   • In cases of penicillin allergy (especially immediate hypersensitivity reactions): macrolides (e.g., azithromycin, erythromycin) or first-generation cephalosporins (considered in cases of non-immediate allergy).
   • Treatment duration: generally 10 days (oral penicillin V); for azithromycin and other drugs, follow the recommended duration for the specific medication.

2. Symptomatic treatment

   • Antipyretics and analgesics (acetaminophen, ibuprofen, etc.)
   • Adequate fluid intake and rest
   • Local soothing measures to relieve sore throat (such as gargling with warm salt water)

3. Indications for hospitalization and emergency treatment

   • Difficulty breathing, persistent high fever, delirium or coma, severe dehydration, severe soft-tissue infection of the neck (such as a cervical abscess), suspected sepsis, etc.

4. Infection control

   • Patients are generally considered noninfectious within 24 hours after starting antibiotics (criteria for ending isolation from childcare facilities, schools, etc., follow local public health guidelines).
   • Contact management: Check family members for symptoms and recommend handwashing and cough etiquette. Treatment of carriers is determined on a case-by-case basis (depending on the presence of symptoms, epidemiological exposure, etc.).

Precautions (Summary)

• Antibiotics must be taken completely as prescribed to reduce the risk of recurrence, carrier status, and complications.
• Be sure to report any history of penicillin allergy, including what type of reaction occurred.
• If symptoms are severe or there is difficulty breathing, difficulty swallowing, or a change in consciousness, visit an emergency department immediately.

Checklist Before an Outpatient Visit (Including Suggested Items to Bring and Questions)

Items to bring (recommended)

• A list of all currently taken medications (including prescription drugs, over-the-counter medicines, herbal medicines, and supplements)
• History of drug allergies (especially the type of reaction to penicillin- or macrolide-class drugs)
• The time symptoms began (such as the date fever started and the date the rash appeared) and records of symptom changes
• Whether similar symptoms have recently occurred among family members or in a group setting, and any absences from school or kindergarten
• A history of previously diagnosed rheumatic fever or kidney disease, or related test results (if available)

Information useful to show the doctor during an outpatient visit

• Temperature records (highest and average)
• Whether difficulty swallowing or respiratory symptoms are present
• Changes in urine output and fluid intake (if dehydration is a concern)

Examples of General Questions to Ask the Doctor

• What are the expected effects and side effects of this antibiotic?
• If I am allergic to penicillin-based drugs, which alternative medication do you recommend?
• If my symptoms do not improve while taking the antibiotic, when should I return for another visit?
• When can I return to school or a childcare facility?
• How great is the risk that this infection will affect the kidneys or heart in the long term?

Examples of Disease-Specific Questions

• If I (or my child) am allergic to penicillin, what are the duration of treatment and side effects of alternative antibiotics (such as azithromycin)?
• Is there a risk of complications such as rheumatic fever or acute glomerulonephritis from this infection? Are additional tests (e.g., urinalysis, cardiac auscultation and echocardiography, ASO titer) needed?

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