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Background Dengue virus (DENV) infection is increasingly common in southern China and can be transmitted through blood transfusion but is not currently part of donor screening throughout the region. We assessed DENV prevalence among donors at the Xishuangbanna Blood Center, Yunnan, to support development of DENV screening strategies. Methods Blood samples were collected randomly between June 2019 and August 2019. These were screened for anti-DENV IgG and IgM using enzyme-linked immunosorbent assay (ELISA). Then, all reactive samples and some randomly-chosen non-reactive samples were used to detect DENV RNAs using real-time polymerase-chain-reaction (RT-PCR) assays. After RT-PCR, samples were further tested for soluble nonstructural protein 1 (NS1) using the colloidal gold method. Donors demographics were also collected and assessed. Results Over the study period, 2254 donor samples were collected and tested for anti-DENV IgG and IgM by ELISA. This revealed 598 anti-DENV IgG and/or IgM reactive samples, a serological prevalence of 26.53%. Of these, 26 were RT-PCR positive and/or NS1 positive. Significant differences in DENV prevalence were noted by occupation (P = 0.001), education (P ), and ethnicity (P = 0.026). Conclusion The prevalence of DENV in Xishuangbanna Blood Center was higher than most other blood centers that have implemented DENV donor screening. Our study provides first-hand data about the prevalence of DENV and allows the development of a screening strategy for clinical use.

BACKGROUND Dengue virus (DENV) can be transmitted through blood transfusion. DENV was not screened regularly in Xishuangbanna Blood Center. This study was conducted in Xishuangbanna Blood Center with an attempt to develop DENV screening strategies in one of China’s high-incidence areas.METHODS Blood samples were collected randomly between June 2019 and August 2019. These samples were first screened for dengue IgG and IgM antibodies using enzyme-linked immunosorbent assay (ELISA). All reactive samples and some randomly-chosen non-reactive samples were used to detect DENV RNAs using real time polymerase-chain-reaction (RT-PCR) assay. After RT-PCR assay, these samples were further tested for soluble nonstructural protein 1 (NS1) using colloidal gold method. The demographic data of DENV positive donors were collected.RESULTS A total of 2,254 donor samples were collected and tested for dengue IgG and IgM antibodies by ELISA between June 2019 and August 2019. ELISA testing revealed that 598 donor samples were anti-IgG and/or anti-IgM reactive, with a serological prevalence rate of 26.53%. Among all the donor samples, 26 were RT-PCR positive and/or NS1 positive. Moreover, there were significant differences in the prevalence rate of DENV in terms of occupation (P=0.001), education(P) and ethnicity (P=0.026). CONCLUSION The prevalence of DENV in Xishuangbanna Blood Center was higher than most other blood centers that have implemented DENV donor screening. Our study provides the first-hand data about the prevalence of DENV and allows development of a screening strategy for clinical use.

The sharp increase of motor vehicle uses greatly increases traffic pressure, and vehicle emissions are one of the main sources leading to haze weather and other climate change problems. An investigation has been undertaken to review Beijing's vehicle development and pollutant emissions trends in recent years. Our data showed that the number of Beijing's automobile ownership has been ranked top in China in recent years, nitrogen oxides emissions are higher than that in other fields, and CO2 emissions is about 10% of the total. Furthermore, the PM2.5 concentration in some major traffic areas of Beijing are monitored, the results showed that there is a PM2.5 pollutant peak at the height of 30m-40m and a lowest PM2.5 concentration at 12:00am-16:00pm on a working day. Finally, by comparing the differences in the vehicles number and management policy among major cities in the word, the author put forward some countermeasures for vehicle administration in Beijing.