Variations in Cerebrospinal Fluid Viral Loads Among Enterovirus Genotypes in Patients Hospitalized With Laboratory-Confirmed Meningitis Due to Enterovirus

Background. Acute enterovirus (EV) meningitis is a major cause of hospitalization among adults and children. It is caused by multiple EV genotypes assigned to 4 species (EV-A, EV-B, EV-C, and EV-D). Methods. We determined viral loads in the cerebrospinal fluid (CSF) of 156 patients of all ages with EV meningitis during a 5-year observational prospective study. The virus strains were genotyped, and their time origin was determined with Bayesian phylogenetic methods. Results. The CSF viral loads ranged between 3.4 and 7.5 log(10) copies/mL (median, 4.9 log(10) copies/mL). They were higher in neonates than in infants and children (P=.02) but were comparable in adults. Viral loads were associated with EV genotypes (P<.001). The EV strains were identified in 152 of 156 patients and assigned to 23 genotypes within the EV-A and EV-B species. The most frequent genotypes, echoviruses 6 and 30, were associated with different viral loads (P<.001). The highest viral loads were in meningitis cases caused by coxsackievirus A9, B4, and B5 genotypes. Most patients infected by a same genotype were infected by a major virus variant of recent emergence. Conclusions. The variations in CSF viral loads in patients at the onset of EV meningitis are related to genotypic differences in the virus strains involved.