ABSTRACT
Objective:To investigate the serotypes and epidemic characteristics of non-polio enteroviruses (NPEV) in acute flaccid paralysis (AFP) cases in Henan Province in 2021.Methods:Fecal specimens of 529 AFP cases reported in Henan Province in 2021 were collected for virus isolation. The VP1 regions of NPEV were sequenced. MEGA5.1 software was used for sequence alignment and a phylogenetic tree was constructed as well. The epidemiological data were organized and statistically analyzed using Excel2016 and SPSS26 software.Results:A total of 30 strains of NPEV were isolated from the fecal specimens of 529 AFP cases, with an isolation rate of 5.67% (30/529). They were belonged to group A and group B with 15 strains in each group, and no group C or group D viruses were isolated. Group A contained six serotypes and was dominated by coxsackievirus A2 (CVA2) and CVA6. Group B contained tree serotypes and was dominated by CVB3. In the population distribution, the separation rate of NPEV was the highest among children under 5 years old, which was 76.67% (23/30), and the ratio of male to female was 1.51∶1. In the regional distribution, group A viruses were mainly distributed in the central, southern and southwestern parts of Henan Province with CVA2 and CVA4 being the most widely distributed, while group B viruses were relatively concentrated, mainly distributed in the central, northern and southwestern parts of Henan Province with CVB3 being the predominant. In terms of time distribution, NPEV could be isolated throughout the year except from January to February, showing the epidemic characteristics of high incidence in spring and summer and low incidence in autumn and winter. The peak of group A virus infection was in May and the peak period of group B virus infection was from June to July.Conclusions:CVB3 was the main serotype of NPEV isolated in Henan Province in 2021. The pathogenic spectrum and regional distribution of NPEV had changed significantly compared with those in 2018-2019. In order to provide reference for the diagnosis and surveillance of AFP and maintain the polio-free status in Henan Province, much attention should be paid to the current epidemic trend of NPEV.
ABSTRACT
Objective:To investigate the types and distribution of non-polio enterovirus (NPEV) in acute flaccid paralysis (AFP) cases in Henan Province in 2019.Methods:A total of 513 cases of AFP were reported in Henan Province in 2019. Two stool specimens were collected from each case for virus isolation. The VP1 gene of NPEV-positive strains was amplified and sequenced. Sequence alignment and construction of the phylogenetic tree were completed by MEGA5.1 software. The epidemiological data of NPEV-positive strains were statistically analyzed by Excel 2016 and SPSS19 software.Results:A total of 39 NPEV strains were isolated from 513 AFP cases, with an isolation rate of 7.60% (39/513). Among them, 18 strains were group A viruses and 21 strains were group B viruses. Both group A and group B viruses contained seven serotypes. No viruses of group C and group D was isolated. Coxsackievirus A type 4 (CVA4) and CVA16 were the predominant types in group A, and echovirus type 11 (Echo11) was the predominant type in group B. The nucleotide identity between the NPEV-positive strains was 67.4%-100.0%, and their nucleotide identity with the prototype strain was 71.4%-85.6%. NPEV was mainly detected in scattered children under 7 years old with an isolation rate of 84.62% (33/39), and the ratio of male to female was 2.07∶1. No statistically significant difference in the isolation rate was found between different age groups or between different sexes ( P>0.05). Among the group A viruses, CVA2, CVA4 and CVA16 were widely distributed. Echo3, Echo11 and Echo30 were the widely distributed group B viruses. NPEV could be isolated throughout the year except for January. Group A virus infections mainly occurred from April to July, accounting for 66.67% (12/18) of the whole year. Group B virus infections mainly occurred in September, accounting for 28.57% (6/21) of the whole year. Conclusions:The main serotype of NPEV isolated in Henan Province in 2019 was Echo11. The pathogen spectrum and regional distribution of NPEV as well as the isolation rate in different age groups changed significantly compared with those in 2018. Therefore, it was necessary to strengthen monitoring and conduct targeted prevention and control to effectively reduce the occurrence of AFP.