Roseola

Definition
Roseola, also called roseola infantum, exanthem subitum, or sixth disease, is a common, usually mild viral illness that primarily affects infants and young children. It is characterised by sudden high fever followed by the appearance of a pink maculopapular rash as the fever resolves.

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Cause

• Most commonly caused by human herpesvirus 6 (HHV-6)

• Less frequently by human herpesvirus 7 (HHV-7)

• Spread via respiratory droplets or saliva from healthy carriers

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Risk Factors

• Children aged 6 months to 2 years (peak incidence: 6–15 months)

• Close contact in nurseries or childcare settings

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Pathophysiology

• HHV-6/HHV-7 infects CD4+ T lymphocytes, causing viraemia and triggering immune response

• After primary infection, the virus becomes latent but can reactivate in immunocompromised individuals

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Clinical Features

Stage 1: Febrile Phase

• Sudden onset of high fever (often >39.5 °C) lasting 3–5 days

• Irritability, mild cough, nasal congestion, eyelid swelling

• Occasionally febrile seizures (due to rapid temperature rise)

Stage 2: Rash Phase

• As fever subsides, a non-itchy, pink maculopapular rash appears, starting on the trunk and spreading to neck, face, and extremities

• Rash typically fades within 1–2 days without scaling or pigmentation changes

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Diagnosis

• Clinical diagnosis based on age, pattern of fever resolution, and subsequent rash

• Laboratory tests rarely needed but may include:

  • HHV-6 serology (in atypical cases)

  • CBC: mild lymphocytosis or leukopenia during fever

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Treatment

Supportive Care (mainstay — as it is self-limiting)

• Maintain hydration

• Paracetamol or ibuprofen for fever and discomfort (avoid aspirin in children)

• Monitor for febrile seizures and provide appropriate first aid if they occur

Antivirals

• Not indicated in healthy children

• In severe or immunocompromised cases, ganciclovir or foscarnet may be considered under specialist care

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Complications

• Febrile seizures (most common)

• Rare: encephalitis, hepatitis, pneumonia (usually in immunocompromised patients)

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Quick-Reference Clinical Chart — Roseola

Feature	Details
Definition	Viral illness with high fever followed by rash, mainly in young children
Cause	HHV-6 (most common), HHV-7
Transmission	Respiratory droplets, saliva
Incubation	5–15 days
Key Symptoms	High fever, irritability, mild upper respiratory symptoms
Key Signs	Maculopapular rash appearing as fever subsides
Diagnosis	Clinical
Treatment	Supportive (hydration, fever control)
Complications	Febrile seizures, rare CNS involvement
Prognosis	Excellent; self-limiting