[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Human herpesviruses](https://durgical.com/en/microbiology/groups/human-herpesviruses/) › Human herpesviruses 6 and 7

[Microbiology](https://durgical.com/en/microbiology/) · [Human herpesviruses](https://durgical.com/en/microbiology/groups/human-herpesviruses/)

# Human herpesviruses 6 and 7

- Virus
- Enveloped
- Exam priority: medium

Herpesviruses that cause roseola in infants: several days of high fever and, as it breaks, a pink rash.

Updated 2026-11-01

Also called: HHV-6, HHV-7, roseola, exanthem subitum, sixth disease

## Key points

- Roseola: the rash appears when the fever breaks.
- A common cause of febrile seizures in infants.
- A betaherpesvirus that infects CD4 T cells.
- Standard precautions.

## At a glance

**Shape**
Icosahedral with tegument and envelope

**Genome**
Linear double-stranded DNA

**Envelope**
Enveloped

**Family**
Herpesviridae (betaherpesvirus, genus Roseolovirus)

**Size**
About 150 to 200 nm

## Morphology

- Typical herpesvirus structure
- Infect mainly CD4 T cells

## Transmission

- Saliva from adults and children who shed the virus
- Nearly all children are infected in the first years of life

**Reservoir:** Humans

### Isolation precautions

What the care team adds to standard precautions.

- Standard

## Virulence factors

- Persists after infection; replicates in CD4 T cells, and the main latency cell is still debated (monocytes are proposed)
- Reactivation in transplant recipients, with fever, bone marrow suppression or encephalitis

## Diseases it causes

- Roseola (exanthem subitum) [Roseola infantum (exanthem subitum) →](https://durgical.com/en/conditions/roseola-infantum/)
- Febrile seizures and, rarely, encephalitis

## Clinical picture

- Infants from 6 months to 2 years: sudden high fever for several days while the child looks fairly well
- As the fever breaks, a pink maculopapular rash appears on the trunk
- High fever can trigger febrile seizures

## Diagnosis

- Clinical diagnosis from the sequence of fever then rash
- PCR or serology in atypical cases or in transplant recipients

## Treatment

Supportive care with antipyretics for roseola. In immunocompromised patients with severe disease, ganciclovir or foscarnet have been used.

Drug class only; doses and regimens are set by the clinician from the current guideline.

## Prevention

- No vaccine
- Standard precautions

## Memory aid

First the furnace, then the flowers: days of fever and, once it cools, the roses bloom (roseola).

## Test yourself

Think of the answer, then tap the question to see it.

## When does the rash appear in roseola?

When the high fever of several days breaks, typically in an infant who looked fairly well.

## Which neurologic complication is common in roseola?

Febrile seizures from the sudden high fever.

## Which viruses cause exanthem subitum?

Human herpesvirus 6 (mainly 6B) and, less often, human herpesvirus 7.

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## Related

- [Parvovirus B19](https://durgical.com/en/microbiology/parvovirus-b19/)
- [Cytomegalovirus](https://durgical.com/en/microbiology/cytomegalovirus/)

## Related conditions

- [Roseola infantum (exanthem subitum)](https://durgical.com/en/conditions/roseola-infantum/)

## What the colours mean

**Gram-positive**
Thick peptidoglycan wall: stains purple.

**Gram-negative**
Thin wall with an outer membrane: stains pink.

**Acid-fast**
Lipid-rich wall (mycobacteria): Ziehl–Neelsen stain.

[← Back to the group: Human herpesviruses](https://durgical.com/en/microbiology/groups/human-herpesviruses/)

Educational content on microorganisms; not a treatment guide and no substitute for a health professional's advice. No doses are given.

Sources: [Roseola](https://medlineplus.gov/ency/article/000968.htm) (MedlinePlus (NLM), 2024); [Appendix A: Type and Duration of Precautions Recommended for Selected Infections and Conditions](https://www.cdc.gov/infection-control/hcp/isolation-precautions/appendix-a-type-duration.html) (CDC, 2024).

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Representative model, for educational purposes only.

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Source: https://durgical.com/en/microbiology/human-herpesviruses-6-and-7/
License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/microbiology/human-herpesviruses-6-and-7/