Objective:To analyze the epidemiological and etiological characteristics of a dengue fever outbreak in Hunan province in 2018.Methods:Real-time PCR assay was performed for the laboratory diagnosis of 8 suspected dengue fever cases. Etiological surveillance was performed in 186 suspected dengue fever cases and fever cases who had close contacts with dengue fever patients. C6/36 cells was used for the virus isolation from acute phase serum. By sequencing the full length of E genes of 15 dengue virus strains, phylogenetic analysis was performed based on the sequences obtained, including reference sequences from the NCBI GenBank database, the serotypes and gene subtypes of the virus were analyzed to trace the possible source of transmission. An emergency monitoring of vector density and a retrospective survey of sero-epidemiology in healthy population were conducted in the epidemic area.Results:In the serum samples of 8 suspected patients, 6 were dengue virus RNA positive, and 4 were NS1 antigen positive. In 186 suspected patients, 96 were dengue virus nucleic acid, NS1 antigen or antibody positive in etiological test. A total of 64 dengue virus strains were isolated. The phylogenetic analysis showed that all the dengue virus strains belonged to type 2, which might be from Guangdong or Zhejiang provinces. The Bretub index was up to 65, indicating an extremely high risk of transmission. The positive rate of the dengue virus IgG antibody was 0.53%(2/377) in retrospective survey of 377 healthy people.Conclusion:The field epidemiologic and the molecular genetics analyses showed the outbreak of dengue fever in Hunan in 2018 was caused by imported cases and dengue virus 2.

An ultra performance liquid chromatography method has been developed for determination of flavones in different origin and different parts from Bupleurum smithii var. parvifoliaum. The separation was performed at 30 degrees C on an Acquity UPLC BEH C18 column eluted with methanol and 0.1% phosphoric acid solution as mobile phases in gradient elution. The detection wavelength was set at 256 nm and the flow rate was 0.4 mL x min(-1). There flavones of rutin, quercetin and isorhamnetin were separated well, the linear calibration curves were obtained over the ranges of 0.106-1.06 microg for rutin (r = 0.999 8, n = 6), 0.004 87-0.048 7 microg for quercetin (r = 0. 999 7, n = 6), 0.022 0-0.220 microg for isorhamnetin (r = 0.999 8, n = 6). The mean recoveries of the three compounds were 99.3%, 97.8%, 98.9% with RSD of 2.4%, 3.0%, 3.2%. The result showed that the method is convenient and feasible for determination of the flavone content in B. smithii var. parvifoliaum.
Bupleurum ; chemistry ; China ; Chromatography, High Pressure Liquid ; instrumentation ; methods ; Drugs, Chinese Herbal ; analysis ; standards ; Flavones ; analysis ; Quality Control