[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Microbiology](https://durgical.com/en/microbiology/) › [Other RNA viruses](https://durgical.com/en/microbiology/groups/other-rna-viruses/) › Human parechovirus

# Human parechovirus

- Virus
- Non-enveloped (naked)

## Contact?

Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.

- For completeness

A common childhood virus related to enteroviruses. In babies under 3 months it can cause a sepsis-like illness, seizures and meningoencephalitis.

Updated Nov 13, 2026

Also called: PeV-A, PeV-A3, formerly echovirus 22 and 23

## Quick facts

**Type**
Virus · [Other RNA viruses](https://durgical.com/en/microbiology/groups/other-rna-viruses/)

**Gram / shape**
Icosahedral

**Spread**
Faecal-oral and respiratory

**Causes**
Sepsis-like illness · Mild respiratory

**Treatment**
There is no specific antiviral

On this page

- The basics Key points
- At a glance
- Morphology
- Transmission
- Memory aid
- What the colours mean

- Clinical Virulence factors
- Diseases it causes
- Clinical picture
- Diagnosis

- Treatment Treatment
- Prevention

- Study Test yourself

- Connections Connections

## Key points

- Picornavirus related to enteroviruses; PeV-A3 is the severe type
- Sepsis-like illness and meningoencephalitis in infants under 3 months
- CSF often has no pleocytosis
- Enterovirus PCR misses it: request parechovirus PCR
- Treatment is supportive

## At a glance

**Shape**
Icosahedral

**Genome**
Single-stranded, positive-sense RNA

**Envelope**
Non-enveloped (naked)

**Family**
Picornaviridae, genus Parechovirus (species Parechovirus A)

**Size**
About 28 to 30 nm

## Morphology

- Naked picornavirus capsid; types 1 and 2 were first classified as echoviruses 22 and 23
- Many types exist; PeV-A3 is the one most linked to severe neonatal disease
- Different enough from enteroviruses that enterovirus PCR assays do not detect it

## Transmission

- Faecal-oral and respiratory, from people with or without symptoms
- Shedding lasts 1 to 3 weeks from the throat and up to 6 months in stool
- Summer and autumn circulation; PeV-A3 rises every two years or so
- Contact precautions for diapered infants, as with enteroviruses

**Reservoir:** Humans

### Isolation precautions

What the care team adds to standard precautions.

**Contact**
Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.

## Virulence factors

- Most children are infected before school age with mild illness
- In young infants with immature immunity PeV-A3 spreads to blood and CNS
- Brain injury affects mainly periventricular white matter, often with little inflammation in CSF

## Diseases it causes

- Sepsis-like illness in infants under 3 months [Neonatal sepsis →](https://durgical.com/en/conditions/neonatal-sepsis/)
- Meningitis and meningoencephalitis with seizures [Viral (aseptic) meningitis →](https://durgical.com/en/conditions/viral-meningitis/)
- Encephalitis with white-matter injury in neonates [Viral encephalitis (herpes simplex encephalitis) →](https://durgical.com/en/conditions/viral-encephalitis/)
- Mild respiratory or gastrointestinal illness with fever and rash in older children

## Clinical picture

- Young infant with high fever, irritability, poor feeding, mottled skin, tachycardia: looks like bacterial sepsis
- Seizures and apnoea in meningoencephalitis
- A red, sometimes palmoplantar rash in some infants
- Long-term neurodevelopmental effects can occur but are uncommon

## Diagnosis

- PeV-specific RT-PCR on CSF and blood; multiplex meningitis-encephalitis panels often include it
- CSF usually shows few or no white cells and normal protein and glucose, which can falsely reassure
- Enterovirus-only PCR is negative: ask for parechovirus specifically
- Brain MRI may show diffusion restriction in periventricular white matter

## Treatment

There is no specific antiviral: care is supportive (fluids, seizure control, respiratory support). Empirical antibiotics are usually started for a febrile young infant until bacterial infection is excluded.

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

## Prevention

- Hand hygiene, especially after nappy changes, for anyone caring for newborns
- Keep sick family members away from young infants when possible
- No vaccine exists

## Memory aid

"Pare-cho: para (stop) and check": a febrile baby with a clean CSF should make you stop and ask for parechovirus PCR.

## Test yourself

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

## Which parechovirus type is most linked to severe neonatal disease?

PeV-A3.

## Why can a normal CSF cell count be misleading in a febrile infant?

Parechovirus meningoencephalitis often causes little or no pleocytosis.

## Why might a routine enterovirus PCR be negative in parechovirus infection?

Parechoviruses are a different genus and need their own specific PCR.

[Add to my cards (3)](https://durgical.app/estudiar/?add=/en/microbiology/human-parechovirus/)

## 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.

**Contact**
Gown and gloves; dedicated equipment. For C. difficile, soap-and-water hand washing.

**Droplet**
Surgical mask within about a metre; single room.

**Airborne**
N95 respirator and a negative-pressure room.

## Connections

## Related 3

- [Enteroviruses](https://durgical.com/en/microbiology/enteroviruses/)
- [Herpes simplex virus 2](https://durgical.com/en/microbiology/herpes-simplex-virus-2/)
- [Streptococcus agalactiae](https://durgical.com/en/microbiology/streptococcus-agalactiae/)

## Related conditions 3

- [Neonatal sepsis](https://durgical.com/en/conditions/neonatal-sepsis/)
- [Viral (aseptic) meningitis](https://durgical.com/en/conditions/viral-meningitis/)
- [Viral encephalitis (herpes simplex encephalitis)](https://durgical.com/en/conditions/viral-encephalitis/)

[← Back to the group: Other RNA viruses](https://durgical.com/en/microbiology/groups/other-rna-viruses/)

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

Sources: [Recent Reports of Human Parechovirus (PeV) in the United States—2022](https://archive.cdc.gov/www_cdc_gov/han/2022/han00469.html) (CDC Health Alert Network (archived), 2022); [Parechovirus A Circulation and Testing Capacities in Europe, 2015–2021](https://wwwnc.cdc.gov/eid/article/30/2/23-0647_article) (CDC, Emerging Infectious Diseases, 2024).

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Representative model, for educational purposes only.

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