Infectious Disease: Scarlet Fever

Question 1

Defintion

Answer 1

Scarlet fever is an infectious disease caused by endotoxins produced by bacteria from the group A β-haemolytic streptococcus class.

Question 2

Epidemiology

Answer 2

• Children under 10 years of age
• Extremes of age: most common in children
• Postpartum women
• Immunosuppression: diabetes mellitus , malignancy, iatrogenic (steroids)
• Concurrent illness: varicella , influenza
• Intravenous drug use
• Alcohol dependence
• Overcrowding

Question 3

Aetiology

Answer 3

Group A β-haemolytic streptococcus class:
MC causative organism is Streptococcus pyogenes

Question 4

Pathophysiology

Answer 4

The illness is highly contagious and transmitted via infected saliva or mucus through aerosol transmission or by direct contact . It most commonly affects children between the ages of 5-15 years of age. The incubation period is typically 2-3 days, and patients can remain infectious for up to 3 weeks unless treated

Question 5

Signs

Answer 5

Petechiae on the hard and soft palate: FORCHHEIMER SPOTS
Strawberry tongue: erythema, white exudate, enlarged papillae
Rash:
- Widespread
- Erythematous
- Blanching
- Pinpoint ‘sandpaper’ texture
- Accentuated in flexor creases
- Begins on the trunk
- Spares palms and soles
Cervical lymphadenopathy
Facial flushing with circumoral pallor

Question 6

Symptoms

Answer 6

Sore throat
Fever: typically > 38.3
Fatigue
Nausea and vomiting
Headache

Question 7

Diagnosis

Answer 7

Throat swabs + blood tests are not routinely indicated for diagnosis

A throat swab for culture of Group A streptococcus can be considered before treatment if:
- Significant diagnostic uncertainty
- A case is suspected as part of a public health outbreak
- Penicillin allergy: to guide antimicrobial choice
- The patient is a close contact of high-risk individuals : healthcare worker, immunosuppressed

Measurement of anti-streptolysin O (ASO) antibody titres can be helpful in the diagnosis of post-infection complications e.g rheumatic fever but not in the acute stage of infection.

Question 8

Management

Answer 8

Hospitalisation if:
- severe symptoms
- suspected life-threatening complications
- high risk of developing complications
Mild to moderate illness:
- general advice: simple analgesia, increase fluid intake
- FIRST LINE = PHENOXYMETHYLPENICILLIN (penicillin V) for 10 days
- AZITHROMYCIN for 5 days if penicillin CI

Question 9

Notifiable disease

Answer 9

Scarlet fever is a notifiable disease and prompt referral to Public Health England (PHE) should be made. In addition, advice should be given to prevent transmission of the condition:
- Exclusion from nursery, school, or work: for at least 24 hours after starting antibiotic treatment
- Encourage effective handwashing
- Avoid sharing towels or utensils
- Avoid contact with high-risk individuals

Question 10

Complications

Answer 10

Complications of scarlet fever are typically suppurative (pus-formation) or non-suppurative with non-suppurative complications classically occurring later:
- Suppurative:
= Otitis media
= Throat abscess: peritonsillar, retropharyngeal
= Acute sinusitis
= Mastoiditis
- Non-suppurative:
= Rheumatic fever : 2-3 weeks post-infection
= Post-streptococcal glomerulonephritis: 2 weeks post-infection
- Invasive Group A streptococcal infection (iGAS): (rare complication)
= Streptococcal pneumonia
= Meningitis and cerebral abscess
= Endocarditis
= Septic arthritis
= Liver abscess
= Cellulitis
= Necrotising fasciitis
= Streptococcal toxic shock syndrome