Cluster of Parechovirus Infections Seen in Young Infants

Researchers warned about symptoms of parechovirus central nervous system (CNS) infection, based on a cluster of 23 young infants admitted to a single children’s hospital over a 6-week period.

From April 12 to May 24 of this year, 23 previously healthy infants ages 5 days to 3 months were admitted to a Tennessee children’s hospital for human parechovirus meningoencephalitis, reported Romney Humphries, PhD, of Vanderbilt University Medical Center in Nashville, and co-authors in Morbidity and Mortality Weekly Report.

Most infants presented with fever, fussiness, and poor feeding without significant cerebrospinal fluid (CSF) inflammation, the researchers said.

When parechovirus is circulating, clinicians should consider testing for it in young infants, including those with normal CSF parameters, Humphries and colleagues urged.

“The rapid detection of parechovirus in CSF by multiplex molecular panels can limit antibiotic administration and improve patient management,” they wrote. “Parents with young infants, especially those with infants aged <3 months, should be aware of the symptoms and visit a pediatrician if symptoms persist.”

The report follows a CDC health alert issued 2 weeks ago that warned about parechovirus infections in neonates and young infants in multiple states.

Human parechovirus belongs to the family Picornaviridae and is divided into several genotypes. Parechovirus genotype 1 is most prevalent and commonly causes respiratory and gastrointestinal symptoms. Genotype 3 is responsible for most severe cases, with a bi-annual pattern of circulation that peaks during summer months. These cases may include severe sepsis-like disease and CNS infection. Infants younger than 3 months have an increased risk of severe illness.

The 23 infants admitted to the hospital had a median age of 24 days; 13 were girls and 10 were boys. Five patients were preterm, born at 28-36 weeks’ gestation. Mean hospital stay was 4.5 days (range 1-26 days).

Nearly all children became symptomatic in the community; one preterm infant became symptomatic in the neonatal intensive care unit (NICU). Most patients (70%) had siblings at home or were exposed to other children.

Four infants had leukopenia. Twenty-two patients had a CSF cell count performed; seven specimens showed an elevated white blood cell count, including three with probable blood contamination during collection.

Four infants developed severe disease requiring treatment in the NICU. Brain MRI of these NICU patients showed white matter diffusion consistent with typical parechovirus meningoencephalitis in all four infants.

Antibiotics were initially prescribed for the 23 infants but were discontinued for 13 patients within 24 hours of detecting parechovirus. Most infants (91.3%) recovered without complications. One patient was scheduled for a follow-up assessment for possible late-onset hearing loss and hypercoagulation evaluation. Another had persistent seizures and may experience severe developmental delay.

Reasons for this cluster of CNS infections are unclear, Humphries and co-authors noted. In 2018, 19 cases were detected over 5 months at the hospital. Cases did not peak in 2020, perhaps due to social isolation during the COVID-19 pandemic, the researchers suggested. So far, 29 cases have been detected at the hospital in 2022, including the 23 in this report.

Although parechovirus infection is not a reportable disease, the Tennessee Department of Health was notified.