| Dengue virus(DENV),a single-stranded RNA virus and Flaviviridae family member,is transmitted by Aedes aegypti and Aedes albopictus mosquitoes.DENV causes dengue fever,which may progress to dengue hemorrhagic fever or dengue shock syndrome.Hospital-based surveillance was performed in two Chinese regions,Guangzhou and Xishuangbanna,during the dengue epidemics in 2014 and 2015,respectively.Acute-phase serum was obtained from 133 patients with suspected dengue infections during the peak season for dengue cases.Viremia levels,virus sero-positivity,serotype distribution,infection type,clinical manifestations and virus phylogenetics were investigated.Of the 133 serum samples,69(51.88%)were positive for DENV RNA.Of the 112 DENV-confirmed cases,92(82.14%)were IgM antibody-positive for DENV,and 69(51.88%)were positive for DENV RNA.From these cases,47(41.96%)were classified as primary infections,39(34.82%)as secondary infections and 26(23.21%)as undetermined infections.The viremia levels were negatively correlated with IgM presence,but had no relationship with the infection type.DENV-1 genotype V dominated in Guangzhou,whereas the DENV-2 Cosmopolitan genotype dominated in Xishuangbanna,where fewer DENV-1 genotype I cases occurred.DENV-2 is associated with severe dengue illness.One substitution(D215N in the envelope gene)was observed in the Xishuangbanna DENV-2 isolates.The strains isolated during 2014-2015 are closely related to the isolates obtained from other Chinese regions and to those isolated recently in Southeast Asian countries.Our results indicate that DENV is no longer an imported virus and is now endemic in China.An extensive sero epidemiological study of DENV and the implementation of vector control measures against it are now warranted in China. |
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