Omnipresent infection occurring in infancy and childhood; majority of cases are caused by human herpesvirus 6 (HHV-6); may be associated with other diseases including encephalitis
- Acute infection of infants or very young children (1)
- Causes a high fever followed by a skin eruption as the fever resolves (1)
- Transmission via contact with salivary secretions or respiratory droplet (1)
- Incubation period of 9 to 10 days (1)
- System(s) affected: skin/exocrine, metabolic, gastrointestinal, respiratory, neurologic
- Synonym(s): roseola infantum, exanthem subitum; pseudorubella; sixth disease; 3-day fever (1)
A disease of infants and very young children (2)
- Predominant age
- Predominant sex: male = female (1)
- No seasonal variance
Common—accounts for 20% ED visits for febrile illness among children aged 6 to 8 months
- Peak prevalence is between 9 and 21 months.
- Nearly 100% population carrying HHV-6 by 3 years (1)
- Approximately 20% patients with primary HHV-6 have roseola.
Etiology and Pathophysiology
- HHV-6 and HHV-7 (2)
- Majority of cases (60–74%) due to HHV-6
- Primary infection typically through respiratory droplets or saliva
- Congenital infection/vertical transmission occurs in 1% of cases (1).
- Transplacental transmission
- Chromosomal integration (clinical significance unknown)
- Lifelong latent or persistent asymptomatic infection occurs after primary infection (1).
- 80–90% of population intermittently sheds HHV-6/HHV-7 in saliva (2).
- Patients are viremic from 2 days prior to fever until defervescence and onset of rash.
- HHV-6 latency is also implicated in CSF.
HHV-6 is integrated into the chromosomes of 0.2–3.0% of the population. This leads to vertical transmission of the virus. Clinical significance of this is unknown (1).
- Female gender
- Having older siblings
- At-risk adults: immunocompromised
- Renal, liver, other solid organ, and bone marrow transplant (BMT)
- HHV-6 reactivation can occur in 1st week posttransplant. HHV-6 viremia occurs in 30–45% of BMT within the first several weeks after transplantation.
- Usually asymptomatic
- Up to 82% of HHV-6 reactivation/reinfection in solid organ transplant
- Nonrisk factors
- Child care attendance
- Method of delivery
- Breastfeeding (HHV does not appear to pass through breast milk.)
- Maternal age
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