Widespread circulation of a new echovirus 30 variant causing aseptic meningitis and non-specific viral illness, South-East France, 2013

Background: Human enteroviruses (HEVs) are major cause of aseptic meningitis. A new outbreak of E-30 occurred between April and September 2013 in Marseille, South-East France. Objectives: Better understand what happen locally when an E-30 outbreak occurs. Study design: Laboratory data (identification and characterization of circulating E-30 strains by partial/complete genome sequencing) were analyzed together with clinical data from emergency ward of the public hospital of Marseille. Results: Compared with data from previous years, we observed an excess of HEV infections between April and September 2013. A total of 202 patients were tested positive of which 79% (160/202) had a cerebrospinal fluid tested positive. Because we performed genotyping using clinical specimens, we obtained representative molecular data related to patients tested positive and found a majority (105/119) of echoviruses 30 (E-30). Phylogenetic analysis revealed that E-30 circulating in Europe since 2000 belong to a unique lineage and showed at the intra-genogroup level the temporal circulation of E-30. Molecular data also indicated that majority of E-30 detected (92%) were almost identical. Compared with data from previous years, this outbreak was finally associated with an excess of patients admitted to an emergency ward for meningitis but also for non-specific viral illness. Conclusions: Our data provide new insights into microevolution of E-30: almost all E-30 emerged from local circulation of one parental virus. Moreover, our findings showed that HEV outbreaks cause an excess of emergency ward consultations but probably also an excess of consultations to general practitioners who receive majority of the non-specific viral illness. (C) 2014 Elsevier B.V. All rights reserved.