Recent outbreak of aseptic meningitis in Italy due to Echovirus 30 and phylogenetic relationship with other European circulating strains

Abstract

Background: Enteroviruses (EVs) are common human viral pathogens, causing a variety of diseases, including aseptic meningitis. Recently, EV aseptic meningitis outbreaks have been reported across Europe, but, in Italy, knowledge of recent EV molecular epidemiology is very limited.

Objectives: We report an outbreak of EV aseptic meningitis in 10 adults in North-Western Italy, from October to November 2012. Patients were parents or close relatives of children <5 years old attending the same class of a nursery school, suffering from a mild febrile upper respiratory disease. Phylogenetic relationship with other European circulating strains was analyzed updating E30 circulation in Italy in recent years.

Study design: EVs were detected from cerebrospinal fluid (CSF) specimens with a real-time reverse transcription polymerase chain reaction and virus isolation was achieved from rectal and pharyngeal swabs. For cluster definition and phylogenetic studies, viral VP1 region was directly amplified and sequenced from CSF.

Results: EVs were identified in CSF from all patients and from rectal and pharyngeal swabs in 7 of them. Direct sequencing of CSF revealed the presence of the same Echovirus 30 (E30) in all patients and phylogenetic analysis identified it as a diverging clade within E30 genotype VII, the most recent strain circulating in UK, Finland and Denmark since 2006.

Conclusion: Molecular techniques allowed the rapid identification and typing of E30 from CSF. Phylogenetic analysis revealed that the cluster might be due to a new E30 variant within the genotype VII currently circulating in Europe, thus updating the epidemiology of EV circulation in Italy.

Keywords: Aseptic meningitis; CSF; E30; EV; Echovirus 30; Enterovirus; Outbreak; PCR; cerebrospinal fluid; enterovirus; polymerase chain reaction.