Roseola Infantum (Sixth Disease)

By usmlevideoss

Introduction

Roseola infantum, also known as sixth disease, is a common viral exanthem of early childhood characterized by a high fever followed by a sudden rash once the fever resolves. It is typically a self-limiting illness and primarily affects infants and young children.Its alternative name, exanthem subitum, means “sudden” rash.

Etiology

  • Caused by human herpesvirus 6 (HHV-6) (most common) and, less frequently, human herpesvirus 7 (HHV-7).
  • HHV-6 and HHV-7 are part of the herpesvirus family and establish lifelong latency after the initial infection.

Epidemiology

  • Primarily affects children between 6 months and 2 years of age.
  • Most cases occur by the age of 3, with peak incidence between 6 and 15 months.
  • Worldwide distribution, with most children having been exposed to HHV-6 by early childhood.

Pathophysiology

  • After primary infection, HHV-6 replicates in the salivary glands and lymphocytes.
  • The virus spreads through salivary transmission (close contact).
  • It causes an acute, febrile illness by triggering an immune response, including cytokine release, which is responsible for the fever and rash.

Clinical Manifestations

1.Prodrome:

  • High fever (often > 39°C or 102°F) lasting 3-5 days.
  • The child may appear irritable but is often otherwise well.
  • Febrile seizures can occur in 10-15% of cases due to rapid temperature rise.
  • Palpebral edema causing swollen eyelids resulting in a “sleepy” appearance; 
  • Erythematous papules on the soft palate and uvula (Nagayama spots)

2.Rash phase (exanthem stage):

  • The fever resolves abruptly and is followed by the appearance of a maculopapular, blanching rash starting on the trunk and spreading to the face and extremities.
  • The rash is non-pruritic and typically lasts 1-2 days.

3.Other symptoms:

  • Mild upper respiratory symptoms
  • Lymphadenopathy (posterior occipital or cervical)
  • Mild diarrhea or irritability in some cases
  • Complications: The most frequent complication of roseola is febrile seizures.

Diagnosis

  • Clinical diagnosis based on history of high fever followed by a rash once the fever resolves.
  • Laboratory tests:
    • Usually not needed, but PCR can detect HHV-6 DNA in blood during acute infection.
    • Serology: Detection of rising antibody titers to HHV-6.
    • CBC: May show leukopenia with a relative lymphocytosis.

Treatment

  • Supportive care: The mainstay of treatment.
    • Antipyretics (e.g., acetaminophen or ibuprofen) to control fever.
    • Adequate hydration.
  • Antiviral therapy: Rarely needed. In severe cases (e.g., immunocompromised patients), ganciclovir or foscarnet may be considered.

Prognosis

  • Excellent prognosis: Most cases resolve without complications.
  • Febrile seizures: The most common complication but are generally benign.
  • No long-term sequelae in most children.
  • Lifelong latency of HHV-6 within the host, with rare reactivation in immunocompromised individuals.

Memory Aid or Mnemonic:

“High FEV-RASH”

  • H: High fever for 3-5 days
  • F: Fever resolves before rash appears
  • E: Exanthem starts on the trunk
  • V: Viral cause (HHV-6/HHV-7)
  • RASH: Maculopapular rash that spreads to the face and extremities

Review Questions 

Q.What is the hallmark of roseola? Abrupt onset of high fever followed by abrupt onset of rash 

Q.When will a patient with roseola become non-contagious? With defervescence and appearance of the rash

Q.What is the most frequent complication of roseola? Febrile seizures

SUPERPoint:

Roseola infantum (sixth disease) is a common childhood illness caused by HHV-6, presenting with 3-5 days of high fever followed by a maculopapular rash once the fever subsides. It is generally self-limiting with an excellent prognosis but can be associated with febrile seizures.

SUPERFormula:

Child 6 months to 3 years of age + Sudden onset of high fever breaking into a blanching maculopapular rash after 3-4 days + Nagayama spots + rash starts on trunk and spreads to face/extremities + HHV-6 infection = Roseola Infantum (Sixth Disease)

References:

Shah A, Sobolewski B, Mittiga MR. Roseola Infantum (Exanthem Subitum). In: Knoop KJ, Stack LB, Storrow AB, Thurman R. eds. The Atlas of Emergency Medicine, 5e. McGraw-Hill; 2021.