| Objective To describe the epidemiological characteristics,epidemic virus types and vaccination of hand-foot-mouthdisease(HFMD)in Inner Mongolia during2016-2020.The full-length sequence of VP1 region of representative strains of enterovirus 71(EV-A71)from hand-foot-and-mouth patients in non-union city,year and symptoms was compared to further understand the molecular epidemiology and genetic characteristics(pathogen typing,phylogenetic relationship,recombination analysis,etc.)of HFMD in Inner Mongolia after the launch of inactivated EV-A71 vaccine in China in 2016.Methods Descriptive epidemiological methods were used to analyze the distribution(time,region and population)of HFMD in Inner Mongolia from 2016 to 2020,and real-time PCR was used to analyze the pathogenic composition of HFMD cases.Rt-pcr was used to conduct full-length bidirectional sequencing analysis of the selected EV-A71 strains in Inner Mongolia.Results From 2016 to 2020,a total of 57486 HFMD cases were reported in Inner Mongolia,including 218 severe cases and 2 deaths.The reported incidence rates were55.49/100.000,61.16/100.000,44.82/100.000,62.08/100.000,3.8/100.000,respectively,with an average annual incidence of 45.47/100,000 and an average annual severe disease ratio of 0.31%.The incidence rate was the highest in 2019 and the lowest in 2020.The number of severe cases and the severe cases ratio reached the peak in 2017 and began to decrease year by year thereafter.The onset of the disease was seasonal,with two peak periods of June to August and September to November.In the past 5 years,the number of cases in Ordos city was the highest,with 9975 cases reported,accounting for 17.35% of the total cases.Alxa League reported the least number of cases,with 1,126 cases reported,or 0.02% of the total.The number of male cases was higher than that of female,and the male to female ratio was 1.36:1.The reported cases were mainly concentrated in 0-5 years old group,accounting for82.63%.The occupational distribution is mainly nursery children,scattered children and students.The 10 ev-A71 whole genome sequences were grouped according to mild and severe disease,and were respectively used as Query group for recombination analysis.It was found that both groups had the same recombination phenomenon,including recombination phenomenon in 5’UTR region and CVA8 region,and recombination phenomenon in P2 region and CVA4 region.U(XAM355)2018,V(XAM352)2018,X(HSAD027)2018,J(ET547-HS)2016,K(ET567-HS)2016,H(ET713-HS)2016 were clustered together and were closely related to 2014 Shanghai strain.After 2012,they differentiated into two small branches.63/2010,2010B31,61/2010,2011C008,104/2010,33/2011,2011C35,2011C53,37/2011 clustered together,forming two small branches close to 2012 Hubei,2012 Yunnan and 2014 Shanghai strains.Formed after 2008 and 2009 respectively,R(TL111)2017,T(HSAA200)2018,Q(TL129)2017,O(TL103)2017 come together to form this small branch between 2014 and 2017.Conclusion The incidence of HFMD in Inner Mongolia showed a seasonal distribution,with two incidence peaks.The reported cases were mainly concentrated in0-5 years old group,and the number of male cases was more than that of female cases.The occupational distribution was mainly in nursery children,scattered children and students,and the dominant pathogen types were different in different years and cities.Although the vaccination rate of HFMD in Inner Mongolia Increased year by year,the overall vaccination rate was not high.The sources of ev-A71 epidemic in Inner Mongolia were different in different years,and the gene recombination sites of severe and mild cases were consistent. |
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