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.
Also called: PeV-A, PeV-A3, formerly echovirus 22 and 23
Quick facts
- Type
- Virus · Other RNA viruses
- Gram / shape
- Icosahedral
- Spread
- Faecal-oral and respiratory
- Causes
- Sepsis-like illness · Mild respiratory
- Treatment
- There is no specific antiviral
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 →
- Meningitis and meningoencephalitis with seizures Viral (aseptic) meningitis →
- Encephalitis with white-matter injury in neonates Viral encephalitis (herpes simplex 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
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.
Connections
← Back to the group: 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 (CDC Health Alert Network (archived), 2022); Parechovirus A Circulation and Testing Capacities in Europe, 2015–2021 (CDC, Emerging Infectious Diseases, 2024).
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Representative model, for educational purposes only.