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Objective:To analyze the molecular characteristics of dengue virus (DENV) strains circulating in Shantou city in 2018 and 2019 for elucidating the reasons causing strikingly different dengue fever epidemics during the two years and understanding the transmission characteristics and routes of DENV, and to provide reference for the prevention and control of dengue fever.Methods:Detection of viral nucleic acid contents and amplification and sequencing of E gene were carried out on 872 samples positive for DENV acid in 2018 and 2019. Phylogenetic trees were constructed based on the E gene sequences to analyze the homology of DENV strains. The sources and transmission routes of the strains were also analyzed. Results:A total of 99 sequences of DENV E gene were acquired, including 68 DENV-1 sequences and 31 DENV-2 sequences. The cases of dengue fever were sporadic in 2018. Phylogenetic tree showed the strains isolated in 2018 were from multi-sources and closely related to those found in Guangzhou city and Southeast Asia area. Dengue fever outbreaks occurred in 2019 and most of the prevalent strains were from a single source, which was speculated to be Cambodia. Conclusions:Dengue fever in Shantou city was mainly caused by imported strains of the same year rather than by local strains in previous years. DENV strains in Shantou might be traced back to Southeast Asia area and transmitted to Shantou through many routes.
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Objective@#To analyze the results of various methods to detect dengue virus(DENV) infection and to provide experience for the development of reasonable detection strategies on DENV infection.@*Methods@#An acute phase case infected with type 2 DENV was used as an example to analyze various methods of detection and the relation of their results.@*Results@#While NS1 antigen, IgM and IgG antibody were all negative, the nucleic acid test showed a positive result ; the NS1 coding gene of the DENV strain from the infected case did not mutate significantly; by additional use of NS1 reagents from other manufacturers, the antigen test result turned to weakly positive.@*Conclusions@#To conduct screening of dengue fever cases, the result of nucleic acid detection should also be applied. Moreover, additional use of NS1 reagents from other manufacturers could be helpful in reducing missed diagnosis, and could obtain more reliable result.
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Objective To investigated the etiologic characteristics of Shigella (S.) sonnei strains causing outbreaks and sporadic cases in some areas of Guangdong province and Guangxi Zhuang Autonomous Region during 2014-2016. Methods Fourteen S. sonnei strains isolated from outbreaks and 6 S. sonnei strains from sporadic cases from Guangdong and Liuzhou of Guangxi Zhuang Autonomous Region were tested for antimicrobial resistance and analyzed by pulsed-field gel electrophoresis (PFGE). Six typical strains were selected for whole genome sequencing typing and compared with 51 strains isolated both at home and abroad from NCBI genome database. Results The antibiotic resistance test indicated the isolates had high resistance rate to ampicillin, tetracycline, gentamicin, trimethoprim/sulfamethoxazole and nalidixic acid, while sensitive to azithromycin, chloromycetin and imipenem. PFGE showed high similarity (93.2%) among the strains isolated from different areas. The whole genome sequencing analysis also revealed that all the typical strains wereclustered into a same evolution branch, close to some strains from Korea. Conclusions The S. sonnei strains isolated from some areas of Guangdong and Guangxi Zhuang Autonomous Region showed high resistance to commonly used antibiotics, but they were sensitive to azithromycin, chloramphenicol and imipenem. The isolates in this study also showed similar PFGE patterns and close phylogenic evolution.
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Objective To investigated the etiologic characteristics of Shigella (S.) sonnei strains causing outbreaks and sporadic cases in some areas of Guangdong province and Guangxi Zhuang Autonomous Region during 2014-2016. Methods Fourteen S. sonnei strains isolated from outbreaks and 6 S. sonnei strains from sporadic cases from Guangdong and Liuzhou of Guangxi Zhuang Autonomous Region were tested for antimicrobial resistance and analyzed by pulsed-field gel electrophoresis (PFGE). Six typical strains were selected for whole genome sequencing typing and compared with 51 strains isolated both at home and abroad from NCBI genome database. Results The antibiotic resistance test indicated the isolates had high resistance rate to ampicillin, tetracycline, gentamicin, trimethoprim/sulfamethoxazole and nalidixic acid, while sensitive to azithromycin, chloromycetin and imipenem. PFGE showed high similarity (93.2%) among the strains isolated from different areas. The whole genome sequencing analysis also revealed that all the typical strains wereclustered into a same evolution branch, close to some strains from Korea. Conclusions The S. sonnei strains isolated from some areas of Guangdong and Guangxi Zhuang Autonomous Region showed high resistance to commonly used antibiotics, but they were sensitive to azithromycin, chloramphenicol and imipenem. The isolates in this study also showed similar PFGE patterns and close phylogenic evolution.