The Etiological And Clinical Features Of The Enterovirus-associated Hand,Foot And Mouth Disease/Herpangina Outbreak In Zunyi,China,2019

Objective: The aim of this study was to clarify the genotypes and molecular characteristics of enteroviruses-associated HFMD(hand,foot and mouth disease)and HA(herpangina)in Zunyi,and to analyze the clinical features of patients infected with different enterovirus genotypes.Methods: We collected the information on demographic and clinical characteristics,laboratory data of laboratory confirmed EVs(enterovirus)associated HFMD/HA cases in Hospital between March 1 and July 31,2019.EV types were determined by either one-step real time RT-PCR or partial VP1 gene sequencing and sequence alignment.Differences in clinical characteristics and laboratory results of the cases were compared among patients infected with the most prevalent EV types.Phylogenetic analysis of CVA6,CVA2 and CVA5 were established based on the partial VP1 gene sequences by neighbor-joining method.Results: 1.Of the enrolled HFMD cases,750(91.1%,750/823)were non-EV71/CVA16 associated cases.For HA cases,539(97.3%,539/554)were non-EV71/CVA16 associated cases.2.Genotyping of the enrolled 216 non-EV71/CVA16 HFMD cases showed that CVA6,CVA2,and CVA5 were the top three pathogens,accounting for 62.0%,4.2%,and 2.3%,respectively.Similarly,for the enrolled non-EV71/CVA16 156 HA cases,CVA6,CVA2,and CVA5 were also the most predominant pathogens,accounting for 25.0%,14.7%,and12.8%,respectively.3.Of the genotypes,the proportion of CVA6 infected HFMD cases reached 77.5%,which was higher than the proportion of HA.The proportion of HFMD cases in CVA2,CVA4 and CVA5 was only 28.1%,11.1% and 20.0%,respectively,which was lower than the proportion of HA.4.The proportion of severe patients caused by CVA2,CVA5 and CVA6 infection was significantly higher than that of CVA16 infection(P<0.05),and the fever,high fever and CRP levels in these patients were also significantly higher than those of CVA16 infection(P<0.05).The most common clinical manifestation of nervous system involvement in severe patients is startle reaction,accounting for 48.3%.Patients infected with CVA5 had a higher proportion of neutrophils and a lower proportion of lymphocytes than patients infected with CVA2(P<0.05).5.The phylogenetic analysis of CVA6,CVA2 and CVA5 showed that the strains isolated in Zunyi were in a close genetic relationship to those isolated in Guangzhou,Tianjin and Shanghai.Conclusion: CVA6,CVA2 and CVA5 are the main non-CVA16/EVA71 enteroviruses causing the HFMD/HA outbreak in Zunyi,2019.CVA6,CVA2 and CVA5 are likely to cause severe infection than CVA16,and there are differences in the clinical manifestations and laboratory characteristics of different enterovirus infections.The isolates of CVA6,CVA2 and CVA5 are in a close genetic relationship to the strains identified in other regions of China.