Separating the wheat from the chaff - Optimizing the diagnosis of enterovirus-associated meningitis

Background: Enteroviruses (EV) comprise the single most common cause of aseptic meningitis with variable geographical and temporal epidemiology. While EV-PCR in CSF is considered a gold standard for diagnosis, it is not-uncommon to use stool EV as a surrogate. Our aim was to assess the clinical significance of EV-PCR-positive CSF and stool in the investigation of patients with neurological symptoms. Methods: In this retrospective study from Sheba Medical centre, the largest tertiary hospital in Israel, we collected demographic, clinical and laboratory data of patients with EV-PCR-positive between 2016 and 2020. A comparison between various combinations of EV-PCR-positive CSF and stool was conducted. Data regarding EV strain-type and cycle threshold (Ct) were crossed with clinical symptoms and temporal kinetics. Results: Between 2016–2020, 448 CSF samples with positive EV-PCR were recorded from unique patients, the vast majority of which were diagnosed with meningitis (98%, 443/448). Unlike the diverse strain types of EV background activity, meningitis-related EV showed a clear epidemic pattern. In comparison with the EV CSF+/Stool+ group, the EV CSF-/Stool+ group had frequently more alternative pathogens detected and a higher stool Ct-value. Clinically, EV CSF-/Stool+ patients were less febrile and more lethargic and convulsive. Discussion: The comparison of the EV CSF+/Stool+ and CSF-/Stool+ groups suggests that putative diagnosis of EV meningitis is prudent in the febrile, non-lethargic non-convulsive patients with an EV-PCR-positive stool. Otherwise, the detection of stool EV only, in a non-epidemic setup, especially with a high Ct-value, may be incidental and mandate a continuous diagnostic effort for an alternative culprit.