Ep 150 – Roseola

Roseola infantum is a viral infection primarily affecting infants and young children, most commonly between the ages of 6 and 12 months. It accounts for 10–45% of febrile illnesses in infants, and cases tend to peak in the spring and autumn seasons. Diagnosing roseola is almost always clinical, and for patients with the classic presentation a clinical diagnosis can be made based on physical examination findings and history alone. In this episode, Dr Roger Henderson looks at the causes and typical symptoms of roseola, along with illnesses that may mimic it, treatment options and possible complications of the illness.

Key take-home points

• The main cause of roseola is human herpesvirus 6 (HHV-6B), although in some cases human herpesvirus 7 (HHV-7) is also responsible.
• Historically, roseola was classified as the sixth of the six classic childhood exanthems (hence the name “sixth disease”), following measles, scarlet fever, rubella, Duke’s disease and erythema infectiosum.
• The virus is primarily spread through saliva and respiratory droplets, making it highly contagious among young children.
• Roseola tends to peak in the spring and autumn seasons, although cases can occur year-round.
• Roseola is usually diagnosed based on the classic presentation of a previously healthy infant, 6–24 months of age, with a sudden onset of high fever (up to 40°C or 104°F) for 3–7 days. The fever often then reduces, but in its place the typical exanthema of roseola appears 3–5 days after the onset of the illness. This consists of pink–red macules and papules on the trunk, neck and proximal extremities, and occasionally on the face, and lasts for about 1–2 days before fading away.
• Unlike rashes from other illnesses such as measles or rubella, the roseola rash is not itchy and does not cause discomfort.
• Diagnosing roseola is almost always clinical, and for patients with the classic presentation of roseola a clinical diagnosis can be made based on physical examination findings and history (usually at the time of loss of fever).
• One key differentiator between roseola and other viral illnesses is that in roseola, the rash appears after the fever breaks, whereas in many other viral rashes, the rash and fever occur together.
• In general, symptomatic control is the mainstay of therapy for roseola and includes antipyretics and maintenance of oral hydration.
• There is currently no vaccine for roseola, so the best prevention is good hand hygiene and avoiding exposure to sick children.
• Up to approximately one-third of first-time childhood febrile seizures may be attributed to primary HHV-6 infection.
• In healthy children, complications are rare but can occur.
• The prognosis for roseola is excellent. Most children recover fully within a week with no lasting effects, and there is very little risk of recurrence in healthy individuals.

Key references

1. Leung AK, et al. Curr Pediatr Rev. 2024;20(2):119-128. doi: 10.2174/1573396319666221118123844.
2. PCDS. 2021. https://www.pcds.org.uk/clinical-guidance/viral-exanthems.
3. Stone RC, et al. Int J Dermatol. 2014;53(4):397-403. doi: 10.1111/ijd.12310.
4. Zerr DM, et al. N Engl J Med. 2005;352(8):768-76. doi: 10.1056/NEJMoa042207.
5. Gewurz BE, et al. Curr Infect Dis Rep. 2008;10(4):292-9. doi: 10.1007/s11908-008-0048-1.