| BackgroundNon-polio enterovirus(NPEV)is one of the most common pathogens of human intestinal infection,and similar to Polio-virus(PV),it can cause Acute Flaccid Paralysis,AFP),can also cause serious disease outbreaks or epidemics such as hand,foot,and mouth disease,neonatal infection or aseptic meningitis,seriously affecting people’s production and life.In 2000,WHO confirmed that China was polio-free,and NPEV gradually became the main pathogen isolated from AFP case samples.However,there is no specific monitoring system for NPEV in China,and no systematic and comprehensive study has reported the change in NPEV detection in AFP cases after polio eradication in Guangdong Province.ObjectiveThe objective of this study was to investigate the etiological and epidemiological characteristics of AFP cases in Guangdong Province from 2000 to 2021,to explore the dominant serotypes of NPEV prevalence in the population and environment combined with environmental sewage surveillance,and to understand the dynamic changes of the long-term cycle ofA FP cases and NPEV in the environment since polio eradication.To find the relationship between the outbreak or epidemic trend of the disease and the change of the dominant serotype,and to provide a scientific theoretical basis for the formulation of effective prevention and control measures of enterovirus-related diseases,it is of great significance for the surveillance work.In addition,in the absence of a complete enterovirus monitoring system,environmental monitoring is a powerful and effective tool to investigate the hidden transmission of enterovirus in the population,which may provide data support for the early warning of enterovirus transmission or the judgment of the outbreak.MethodA total of 572 NPEV positive cases were collected from the AFP case network surveillance system in Guangdong Province from January 2000 to December 2021,and the epidemiological analysis was conducted.The 572 strains of NPEV isolated from NPEV positive cases were tested for retransmission,reexamination,VP1 typing,and whole genome amplification sequencing.Combined with 2195 strains of NPEV isolated from environmental sewage from January 2009 to December 2021,the long-term cycle dynamic changes ofNPEV in AFP monitoring and environmental sewage monitoring were obtained,and the dominant serotypes EV-A71 and E11 causing outbreaks were analyzed.Nucleotide and amino acid homology analysis was performed for the obtained gene sequences.In addition,a phylogenetic tree was constructed with the gene sequences of representative strains selected from GenBank for gene subtype analysis and recombinant analysis.Result1.From 2000 to 2021,NPEV positive patients accounted for 7.63%(572/7492)of all AFP cases in Guangdong Province.The number of NPEV positive cases peaked in summer and autumn,mainly from May to June,and the age was mainly 1 to<3 years old.The difference in gender detection was not statistically significant.2.There were 45 serotypes in 572 strains of NPEV,among which the EV-B group accounted for 58.74%(336/572)with 33 serotypes,followed by the EV-A group with 9 serotypes and the EV-C group with 3 serotypes.The most detected serotypes were EV-A71,followed by CVA4,CVB3,and E11.In 2008-2013 and 2016-2017,EV-A71 was dominant,while in 2019,E11 was dominant,and in 2020-2021,more CVB3 was isolated.3.The number of NPEV detected in environmental sewage from 2009 to 2021 peaked in summer and autumn,mainly from May to July.A total of 2195 strains of NPEV were isolated from sewage,with a total of 21 serotypes,among which group EV-B accounted for 99.13%(2176/2195)with 18 serotypes,followed by group EV-A with 1 serotype and group EV-C with 2 serotypes,and E11 was the most isolated serotype.Followed by E6,CVB5,E7 and CVB3.E6 was mainly detected before 2017,E11 showed explosive growth during 2018-2019,and CVB3 was mainly isolated during 2020-2021.4.EV-A71 was the dominant serotype detected in AFP cases,all of which were C4 genotypes,mainly C4a genotype,but the C4b genotype was found in 2000-2001 and 2005.Detection of EV-A71 decreased significantly after the vaccine was released in 2016.EV-A71 was not detected in AFP cases after 2018.5.E11 was the dominant serotype in environmental wastewater monitoring.In 2019,E11 caused two cases of neonatal infection in Guangdong Province,and the two cases of neonatal infection and sporadic cases as well as E11 detected in sewage were all D5 genotypes.In 2018,a large amount of E11 was already detected in sewage and all were D5 genotypes,but the A1 genotype dominated in 2017 and before.Conclusion1.The detection season of AFP cases in Guangdong Province was mainly in summer and autumn,and the detection age was mainly in 1 to 3 years old.2.The serum types of NPEV detected in AFP cases and environmental sewage were 45 and 24,respectively,showing diversity.EV-A71 is the predominant serotype in AFP case surveillance.Detection of EV-A71 increased significantly in 2008 but decreased significantly after the introduction of the EV-A71 vaccine in 2016.E11 is a relatively dominant serotype in environmental sewage monitoring.The detected amount of E11 increased significantly from 2018 to 2019,and no E11 was detected after 2020.3.The occurrence frequency of different serotypes varies with different seasons and spatiotemporal factors,and the dominant serotypes also change with time.Therefore,it is necessary to continuously monitor and explore the molecular epidemiology and distribution of NPEV. |
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