| ObjectivesThis study aimed to monitor the current status of enterovirus(EV)infection in respiratory infection case at a children’s hospital in Kunming,Yunnan from October 2019 to December 2020,So that we could figure out which serotypes of enteroviruses were prevalent and clarify the molecular epidemiological characteristics of respiratory tract infections caused by EV in Kunming,Yunnan and surrounding areas.The epidemiological characteristics could provide experimental basis for the prevention and control of respiratory tract infections caused by enteroviruses.Methods1.During October 2019-December 2020,throat swab specimens from children with respiratory infections were collected at a children’s hospital in Kunming,Yunnan,collecting the basic conditions,clinical symptoms,signs and test results of the children at the same time.2.Fluorescence quantitative PCR was used to detect specimens.Semi-nested reverse transcription-polymerase chain reaction(RT-snPCR)was used to amplify partial VP1 gene fragments of positive specimens.And the successfully amplified specimens were sequenced,genotyped and evolutionary analyzed.3.Data was sorted using Excel 2010.The data graph was drawn by Origin 2019.Data were counted and analyzed by SPSS 17.0.And Phylogenetic tree was analyzed with MEGA6.0.4.Chi-square and Fischer’s exact test method were used to compare the analysis rate and composition ratio between groups.Quantitative grouping data that did not conform to the normal distribution used the Kruskal-Wallis H rank sum test.Results1.During October 2019-December 2020,a total of 1087 specimens were collected from the Infectious Diseases Department of a children’s hospital in Kunming,Yunnan.The positive detection rate of enterovirus was 25.39%(276/1087).The success rate of enterovirus nucleic acid amplification was 69.93%(193/276).The success rate of the gene sequenced was 95.34%(184/193).2.Serotype distribution,evolution and homology analysis2.1 The serotype composition of EV is distributed as follows.EV-A group virus strains was detected with a total of 6 serotype,that were CV-A2,CV-A4,CV-A5,CV-A6,CV-A8,CV-A10.EV-B group virus strains was detected with a total of 8 serotypes,CV-A9,CV-B1,CV-B3,E-6,E-11,E-18,E-30,E-33.EV-C group had only 1 strain that was PV-1.No virus strain in the EV-D group was detected in this study.2.2 Phylogenetic analysis:The virus strains detected in this study were relatively distantly related to the prototype strains.The same genotype virus strains were clustered together.Both the reference strain and the virus strain detected in this study were in the same position as the prototype different evolutionary branches.2.3 Homology analysis:The nucleotide homology between the virus strains in each group of EV-A,EV-B with their prototype strains were 75.2%-85.7%and 75.1%-84.4%,respectively.The nucleotide homology between the virus strains and their reference strains were 79.2%～100.0%and 80.7%～98.3%respectively.In the EV-C group,the nucleotide homology between the PV-1 virus strain and its prototype strain Mahoney and Sabin were 95.3%and 97.2,respectively%.The nucleotide homologybetween PV-1 and its reference strain is 97.8%-99.1%.The nucleotide homology between the EV-A group virus strains in this study was 81.9%-100%,and the EV-B group was 89.6%～100%.3.Population distribution3.1 Gender distribution:There were 106 males and 78 females in the 184 children with EV-positive respiratory infections,male:female=1:0.735.There was no statistical difference in the gender distribution of these serotypes(P=0.086>0.05).Male and female were mainly infected by 5 serotypes viruses,CV-A10,CV-A2,E-11,CV-A4,CV-A6.3.2 Age distribution:The oldest case was 13 years old,the youngest case was 0.29 years old,and the average agewas 3.14±2.21 years old.Children aged 0～3 group accounted for 72.45%.Comparing the differences in age distribution of different EV genomes and serotypes showed that Fischer’s exact test,P<0.05.Different EV genomes and serotypes were different in each age group.EV-A was mainly 2-3 group,accounting for 40.94%,followed by 0-1 group,accounted for 37.58%;EV-B was mainly in the age group 0～1 and>5 group.Both accounted for 32.35%,followed by 2～3 group,accounted for 26.47%.Only one case of EV-C,wich was PV-1.The casa was 4.08 years old.4.Regional distribution:The top five regions with the largest number of monitored cases are Guandu District with 44 cases,Xishan District with 32 cases,Wuhua District with 15 cases,Chenggong District with 14 cases,and Panlong District with 12 cases,accounting for 23.91%,17.39%,8.15%,7.61%and 6.52%,respectively.Tested by Fischer’s exact test,P=0.0322<0.05,15 serotypes were distributed in 22 regions with statistical differences.5.Time distribution:According to Pearson’s chi-square test,χ2＝1.654,P=0.198>0.05,there was no significant difference in the EV detection rate in children with respiratory infections between 2019 and 2020.6.Analysis of clinical characteristics of different serotypes6.1 The 184 cases of respiratory tract infection were mainly caused by five serotypes of enterovirus CV-A10,CV-A2,CV-A6,CV-A4 and E-11.The disease spectrum was:infectious fever(62 cases/33.70%),herpetic angina(47 cases/25.54%),bronchial pneumonia(32 cases/17.39%),bronchitis(15 cases/8.15%),pneumonia(12 cases/6.52%),acute upper respiratory tract infection(10 Cases/5.43%),severe pneumonia(6 cases/3.26%),the main clinical symptoms are fever and cough.6.2 The white blood cell(H=37.019,P<0.001)and neutrophil(H=43.174,P<0.001)counts of the clinical laboratory results of different serotypes were statistically significant,and the white blood cells and neutrophils of each genotype could be considered The cell counts were different;the lymphatic counts of different serotypes were not statistically significant(H=16.401,P=0.269).Conclusions1.In Kunming,Yunnan and its surrounding areas,the situation of EV causing respiratory tract infections in children was complicated,with many serotypes and different distributions,mainly in the EV-A and the EV-B.CV-A10 and CV-A2 were dominant enteroviruses.At the same time,the monitoring results showed that PV-1 in the EV-C group could also cause symptoms of respiratory tract infection.None of virus in EV-D group had been detected.2.Among children with human enterovirus nucleic acid-positive respiratory tract infection,children aged 0-3 group accounted for the highest proportion,no difference in gender distribution,and differences in EV serotypes in different regions.3.Patients with respiratory tract infections caused by EV often had clinical symptoms such as fever and cough.Disease diagnosis mainly includes infectious fever,herpetic angina and bronchopneumonia.4.From the perspective of molecular epidemiology,EV had been prevalent in the population for a long time,spreading across regions,and overall it has the characteristics of high aggregation. |
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