Investigation of enterovirus spectrum in false influenza-like illness cases in Wenzhou, Zhejiang, 2017–2018

ObjectiveTo investigate the enterovirus (EV) spectrum and its main virus types in influenza-like illness (ILI) cases with negative influenza virus detection results, and provide basic scientific evidence for the prevention and treatment of EV infection.

MethodsThe clinical samples of ILI cases were collected in Wenzhou of Zhejiang Province from 2017 to 2018 for the detections of influenza A and B viruses with real-time PCR（polymerase chain reaction）. Then EV detection was performed for influenza negative cases. VP1 region sequence of EV was amplified by using reverse transcription PCR. The amplified products were subjected to gene sequencing and genotyping. Statistical analysis was conducted to evaluate the results.

ResultsAmong 2 298 ILI cases detected, 488 (21.23%) were influenza virus positive, and 1 810 (78.76%) were influenza virus negative, in which 254 (14.03%) were EV positive. EV infections occur all the year round, but the incidence peak was during April-July with the cases accounting for 70.47%. In 254 EV positive cases, by gene sequencing, the genotypes of 135 cases were detected, including 13 EV subtypes of EV-A, EV-B and EV-C, in which Cox A6, Cox A2 and Cox A10 accounted for 24.44%, 22.22% and 13.33%, respectively. There were significant year, month, gender and age specific differences in EV positive rate (χ²＝9.399, 329.380, 4.311, 29.246, all P＜0.05).

ConclusionEnterovirus was one of the main pathogens in false influenza-like infection cases, and enterovirus spectrum was complex. It is necessary to strengthen the diagnosis and surveillance in low age group.