RESUMEN
Objective To understand the epidemiological characteristics and genotype distribution of enterovirus (EV) in influenza-negative influenza-like illness (ILI) cases in Chongqing, and to provide a scientific basis for EV prevention and control. Methods Throat swab samples of influenza-negative ILI cases were collected from surveillance sites. The samples were detected for EV using real-time RT-PCR. The VP4 regions of positive samples were amplified and sequenced for genotyping. Results A total of 3 960 influenza-negative ILI samples were collected from January to December 2021, and 316 (7.98%) of them were EV-positive. EV could be detected in influenza-negative ILI cases in Chongqing all year round. The months with high EV-positive rates were January (11.60%), April (10.56%), May (11.79%), June (12.62%), and July (10.33%). There was a statistically significant difference in the detection rate of EV in ILI cases in different regions, gender, and age groups (χ2=29.647，χ2=4.192，χ2=69.176，P<0.05). A total of 213 EV-positive cases were successfully genotyped, including 17 genotypes of EV-A, EV-B, and EV-C and 5 genotypes of HRV-B. The dominant genotypes were CV-A4 (32.86%), CV-A2 (23.00%), CA-6 (12.21%), and CA-10 (11.74%). EV-D and novel EV were not identified in this study. Conclusion EV is an important pathogen in ILI cases in Chongqing. The prevalence of EV in ILI cases in Chongqing has typical regional, seasonal and population characteristics. Prevention and control should be carried out in Chongqing according to the epidemic characteristics of EV.
RESUMEN
Objective To classify and identify the 53 strains of non-polio enterovirus (NPEV) isolated from acute flaccid paralysis (AFP) cases in Chongqing from 2013 to 2020, and to investigate the genotype distribution of the strains. Methods Commercial real-time fluorescence quantitative polymerase chain reaction (real-time PCR) reagents were used for rapid identification of the strains. The nucleotide sequences of VP1 and VP4 regions were used for genotyping. Results Fifty enteroviruses were identified, 33 (66%) in group A and 17 (34%) in group B. Group C and D enteroviruses were not found in these strains，and 3 strains could not be identified. In this study, EV-A71 was the dominant type, with 11 strains (22%), but EV-A71 strain was not isolated since 2016. The sequences of VP4 region and VP1 region were completely consistent in enterovirus grouping. Conclusion When using commercial real-time PCR reagents for enterovirus typing, the identification results of high CT values may be inaccurate. In the genotyping of enterovirus, the nucleotide sequence of VP4 region is first used for grouping, and then the nucleotide sequence of VP1 region is used for genotyping, which could simplify the experimental process. NPEV isolates from AFP cases in Chongqing showed poor genotype diversity. In order to enrich and improve the enterovirus gene database in Chongqing, it is necessary to carry out research on enterovirus transmitted by respiratory tract.