We investigated the molecular characteristics of the full-length genome of 14 dengue serotype 1 virus (DENV-1)strains isolated in Sino-Myanmar border region in Yunnan Province,China during 2013-2015.Isolation of dengue virus was using C6/36 cell culture method.Viral RNA was extracted from virus isolates,and then the full-length genome was amplified by RT-PCR.The homology and phylogenetic analysis was made on the nucleotide and deduced amino acid sequences by bioinformatics software including ClastalX1.83 and MEGA6 etc.Results showed that fourteen strains of DENV-1 isolated from dengue fever cases,of these,9 strains from Ruili City of Dehong Prefecture,3 from Lincang Prefecture,2 from Kunming City.RT-PCR and sequencing indicated that the full-length genes (10 735 nt) of 14 DENV-1 strains were obtained,and their open reading frame (95-10 271) were coded 3 392 amino acid residues.The genotypes of DENV-1 were revealed by homology and phylogenetic analysis based on structural and non-structural proteins.Thirteen were genotype Ⅰ (G-Ⅰ) (7 from indigenous cases in Ruili and Lincang and 6 from imported case from Myanmar to Ruili,Lincang and Kunming),and 1 G-Ⅲ from imported case from India to Kunming.The phylogenic analysis indicated that the 13 isolates from Yunnan divided into 2 phylogenic subgroups,and they had a closer genetic relationship with the strains isolated from Southeast Asia.The gene sequences of the 13 G-Ⅰ strains have been acquired,the rate of their nucleotide homology and amino acid homology were 97.02 ％-100 ％ and 98.78 ％100 ％ respectively.Compared with 6 strains from Southeast Asia,nucleotide homology and amino acid homology were 96.53％-99.53％ and 97.33％-100％ respectively.Compared with prototype strain (US_Hawaii) of DENV-1,nucleotide homology and amino acid homology were 93.76％-94.45 ％ and 95.86 ％-96.91％ respectively.Compared with US_Hawaii strain,there were 44 and 150 different sites in amino acid of structural and non-structural proteins,respectively.The G-1 of DENV-1 have been popular in Sino-Myanmar border region in Yunnan,2013-2015.They have genetic diversity but multiple transmission sources were from Myanmar,and should strengthen control cross-border spread of dengue fever in this region.It is necessary to further study that change of the amino acid sites of Yunnan strains of DENV-1 is related to its antigenicity and pathogenicity.

Objective:To understand the epidemiological characteristics of an outbreak of Chikungunya fever (CHIK) in Ruili city at Sino-Myanmar border area in Yunnan province, China, 2019.Methods:The data of CHIK cases in Ruili city were collected. Serum samples were collected from acute phase of the patients for the detection of the viral nucleic acid with real-time reverse transcription PCR assay.Results:A total of 121 CHIK cases (laboratory-confirmed cases) were reported in Ruili city in 2019, in which 98 were indigenous cases (80.99%) including 2 pregnant women and 3 neonatal cases (twin boys and 1 girl) were observed with vertical mother-to-child transmission), and 23 were imported cases (19.01%) from Myanmar. CHIK mainly occurred in Urban area (Mengmao town) and port area (Jiegao development zone) of Ruili city. The epidemic of CHIK lasted from September to November. The epidemic peak was in October (74.38%). The majority of patients were aged from 20—59 years (77.69%), in addition to 3 cases of mother-to-child transmission, the youngest was 3 months and the oldest 72 year-old. The male to female ratio was 1∶1.28 (53∶68). Occupational distribution of CHIK cases was mainly for the commercial service personnel (33.06%), home workers and unemployed persons (21.49%) and retiree (11.57%).Conclusions:During the outbreak of CHIK in Ruili in 2019, both indigenous and imported cases were detected. The imported CHIK cases from Myanmar were the main sources for local transmission of CHIK in Ruili city. This is the first time that a local epidemic of CHIK has occurred in Yunnan Province. It is necessary to strengthen control of the cross-border spread of CHIK in this area.

Objective:To understand the clinical characteristics of pregnant women infected with dengue virus (DENV) in Ruili City, Yunnan Province, so as to provide basis for formulating effective diagnosis and treatment protocol of dengue fever in pregnant women.Methods:A total of 18 pregnant women infected with DENV hospitalized in Ruili People's Hospital in 2017 and 2018 were selected as observation group, and 18 non-pregnant women infected with DENV were selected as control group according to the age range of the observation group, and epidemiological and clinical data of patients in the two groups were retrospectively collected. Epidemiological characteristics, clinical symptoms and laboratory biochemical indexes of the two groups were compared and analyzed.Results:There were no significant differences ( t = - 0.032, 0.495, P > 0.05) in age [(27.9 ± 5.3) vs (27.9 ± 5.1) years old] and hospitalization stay [(6.8 ± 1.6) vs (6.6 ± 2.0) d] between the observation group and control group. One pregnant woman in observation group had early pregnancy abortion. Patients of both groups had fever in 18 cases (100.0%), headache, muscle aches, and chills in 14 cases (77.8%), anorexia in 15 cases (83.3%), and nausea and vomiting in 5 cases (27.8%); fatigue in 14 cases (77.8%) and 16 cases (88.9%), respectively; there was 1 case of rash in observation group (5.6%), and no rash in control group. There were no significant differences in the above mentioned clinical symptoms distribution between the two groups ( P > 0.05). On the first day of admission, the reduction proportions in red blood cells [61.1% (11/18) vs 5.6% (1/18)], hemoglobin [50.0% (9/18) vs 16.7% (3/18)], and hematocrit [61.1% (11/18) vs 16.7% (3/18)] in observation group were significantly higher than those in control group ( P < 0.05); on the fifth day of admission, the reduction proportions in hemoglobin [33.3% (6/18) vs 5.6% (1/18)] and hematocrit [33.3% (6/18) vs 5.6% (1/18)] in observation group were significantly higher than those in control group ( P < 0.05). Conclusions:The red blood cells, hemoglobin and hematocrit of pregnant women infected with DENV are significantly reduced, and there is a risk of miscarriage in early pregnancy. It is suggested that relevant departments should strengthen the training of medical staff to diagnose and treat pregnant women infected with DENV early.

Objective: To understand the serotypes, genotypes and transmission source of dengue viruses(DENV) isolated in Yunnan from 2013 to 2015. Methods: Viral RNA was extracted from serum samples of dengue fever(DF) cases at the acute stage in Yunnan, then the gene fragments of envelope protein(E) region were amplified by RT-PCR. The homology and phylogenetic analysis was made on the nucleotide and deduced amino acid sequences by bioinformatics softwares including Clustal X, DNAStar and MEGA5. Results: Viral nucleic acid detection and sequencing indicated that 40 E genes of DENV were obtained. The serotypes and genotypes of DENV were revealed by homology and phylogenetic analysis based on E genes of DENV. Fifteen virus strains belonged to DENV serotype 1(DENV-1), of these, 14(11 from Ruili, 1 from Lincang and 2 from Kunming) were genotype I(G-I), 1 from Kunming was G-V. Twenty-two virus strains belonged to DENV serotype 2(DENV-2), of these, 10 from Ruili were G-I and 12 from Xishuangbanna were G-IV. Two virus strains belonged to DENV serotype 3(DENV-3) and G-II. One virus strain belonged to DENV serotype 4(DENV-4) and G-I. All detected DENV genotypes were mainly predominant in Southeast Asia. All the 40 Yunnan DENV strains shared high homology with the DENV strains in Southeast Asia countries. Conclusions Four serotypes and multiple genotypes of DENV had been co-circulating in Yunnan from 2013 to 2015. The DENV transmitted from Southeast Asia countries was the main cause of DF in Yunnan. It is necessary to strengthen the surveillance and management on the imported cases of DF in Yunnan.