| Objective:To investigate the characteristics of the prevalence,clinic,serotypes and genotypes of dengue fever in Gengma County,Lincang City,Yunnan Province.Providing evidences to make out local effective measurements of dengue prevention and control,as well as diagnosis and treatment.Methods:The samples were collected from the acute serum of dengue fever patients in Gengma County,Lincang City,Yunnan Province in 2019,dengue virus was isolated by the method of BHK cell culture,their serotypes identified by Real-time Quantitative PCR.The E gene sequences of Dengue virus were obtained by RT-PCR,reference sequences were searched and downloaded by establishing high homology in GenBank,the analysis of phylogenetic and amino acid homology(nucleotide similarity)was performed by using biological software such as Chromas 2,SeqMan,Mega5.0,MAFFT online and Megalign.The clinical data were analyzed by using the Excel2017 and SPSS20.0 for their dengue virus serotype differences of epidemiological characteristics,clinical symptoms and signs,and laboratory biochemical indicators.Results:A total of 141 serum samples were collected from acute stage dengue fever in Gengma County,Yunnan Province in 2019,and four dengue virus serotypes were isolated i.e.33 strains of DENV-1(23.40%),43 strains of DENY-2(30.50%),64 strains of DENV-3(45.40%)and 1 strain of DENV-4(0.71%).A total of 30 E gene target fragments were amplified i.e 14 DENV-1 strains(2 imported strains from Myanmar and 12 native strains from Gengma)were all G-Ⅰ.Among them,1 was imported strain from Myanmar and 4 native strains of Gengma were in the same evolutionary branch(amino acid homology was 99.2%-99.6%,nucleotide similarity was 99.1%),aother imported strain from Myanmar was on the same branch with 8 native strains from Gengma County(their amino acid homology 99.4%-100%and nucleotide similarity 99.7%-100%).6 DENV-2 strains were isolated,among them,the two imported strains from Myanmar were G-Ⅰ(Asian Ⅰ genotype)which had the closest genetic relationship with the 2019 Myanmar epidemic strain(MT705604)(their amino acid homology 97.2%-100%and nucleotide similarity 97.6%-99.8%),The other 4 native strains in Gengma County were G-Ⅳ(Cosmopolitan genotype)which had most closely relationship with Guangzhou strain in 2016(MK564477)(their amino acid homology 99.6%and nucleotide similarity 99.4%).10 DENV-3 strains(5 imported strain from Myanmar and 5 native strains from Gengma County)were isolated and all of them belonged to G-Ⅲ,Their amino acid homology of E gene between imported and native cases were 99.2%-100%(their nucleotide similarity 99.1%-100%),as well as with 99.0%-100%amino acid homology and 99.0%-99.6%nucleotide similarity as the 2019 Myanmar strain(MW320451).A total of 140 cases with three DENV serotypes(DENV-1,DENV-2 and DENV-3)were analyzed.In terms of their clinical symptoms,the main features of DENV-1 were fever(96.97%),muscle aches(81.81%),chills(84.85%)and fatigue(87.88%);DENV-2 were fever(84.44%),chills(83.72%)and fatigue(86.05%);DENV-3 were fever(87.50%),muscle soreness(81.25%),chills(92.19%)and fatigue(87.50%),but the three types of DENY were not significantly different in the areas of fever,muscle soreness,chills,and fatigue.In terms of their clinical signs,DENV-1 have 6 cases rash(18.18%),DENV-2 have 10 eases(23.26%),DENV-3 have 32 cases(50.00%),and three types of DENV were significantly different in the areas of rash,especially in DENV-3,which was significantly higher than the other types(P<0.05).In terms of their blood routine indexes,DENV-1 mainly showed the reduction of leukocytes(96.97%),platelets(90.91%),neutrophils(96.97%)and lymphocytes(90.91%).DENV-2 and DENV-3 mainly showed the reduction of leukocytes(86.05%,85.94%)and neutrophils(86.05%,82.81%),three types of DENV were not significantly different in the areas of the reduction of leukocytes,platelets,neutrophils and lymphocytes.However,compared with the lower rate of erythrocyte of DENV-2、DENV-3(46.51%、32.81%),the reduction of erythrocyte of DENV-1 were significantly higher(69.70%).In terms of their liver function indexes,DENV-1、DENV-3 mainly showed the increase of aspartate aminotransferase(42.42%、34.38%),DENV-2 mainly showed the increase of alanine aminotransferase(20.93%).There was no significant difference in the above liver function indexes among the three DENV types(P<0.05)In terms of their cardiac function indexes,DENV-1 mainly showed the increase of lactate dehydrogenase(51.52%)and creatine kinase isozyme(51.52%),while DENV-2 and DENV-3 were mainly showed the increase of creatine kinase isozyme(32.56%and 48.44%).There was significant difference in lactate dehydrogenase of the above cardiac function indexes among three DENY,and the increase rate of DENV-1 was more significant(P<0.05).In terms of their serum lipid indexes,the decrease rate of low density lipoprotein of DENV-1(72.73%)was significantly higher than that of DENV-2、DENV-3(62.79%,46.51%),and the decrease rate of high density lipoprotein of DENV-3(97.67%)was also significantly higher than that of DENV-1、DENV-2(36.36%,65.12%)(P<0.05).In terms of their electrolytes,the decrease of potassium in DENV-2 patients was more significant(44,19%),and the decrease of calcium in DENV-1 patients was more significant(33.33%)(P<0.05).Conclusions:Four DENY serotypes were found in Gengma County,Yunnan Province,in 2019.And a total of four genotypes(DENV-1 G-Ⅰ,DENV-2 Asian Ⅰgenotype,DENV-2 Cosmopolitan and DENV-3 G-Ⅲ)were isolated.Both local DENV-1 and DENV-3 strains were imported the imported strains from the corresponding border areas of Myanmar,and the source of local DENV-2 strains remains to be further studied.In 2019,The clinical features of DF patients in Gengma County were typical.DENV-1 mainly showed the decrease of erythrocyte,serum calcium concentration,low-density lipoproteinincreased and the increase of lactate dehydrogenase(P<0.05);DENV-2 mainly showed decreased serum potassium concentration(P<0.05);DENV-3 was more significant in rash and the decrease of high-density lipoprotein(P<0.05).It is recommended that local health authorities strengthen the training of clinicians to prevent the occurrence of severe DF or death cases. |
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