Abstract
BackgroundIncreases in global travel and trade are changing arbovirus distributions worldwide. Arboviruses can be introduced by travelers, migratory birds, or vectors transported via international trade. Arbovirus surveillance in field-collected mosquitoes may provide early evidence for mosquito-borne disease transmission.MethodsDuring the seasons of high mosquito activity of 2018, 29,285 mosquitoes were sampled from seven sentinel sites in various insect regions. The mosquitoes were analyzed by RT-PCR for alphaviruses, flaviviruses, and orthobunyaviruses.ResultsWe detected three strains of Japanese encephalitis virus (JEV), five strains of Getah virus (GETV), and 45 strains of insect-specific flaviviruses including Aedes flavivirus (AeFV, 1), Chaoyang virus (CHAOV, 1), Culex flavivirus (CxFV, 17), Hanko virus (HANKV, 2), QuangBinh virus (QBV, 22), and Yunnan Culex flavivirus (YNCxFV, 2). Whole genomes of one strain each of GETV, CxFV, CHAOV, and AeFV were successfully amplified. Phylogenetic analysis revealed that the new JEV strains detected in the Shanghai and Hubei Provinces belong to the GI-b strain and are phylogenetically close to the NX1889 strain (MT134112) isolated from a patient during a JE outbreak in Ningxia in 2018. GETVs were found in Inner Mongolia, Hubei, and Hainan and belonged to Group III. They were closely related to strains isolated from swine. HANKV was recorded for the first time in China and other ISFVs were newly detected at several sentinel sites. The bias-corrected maximum likelihood estimation value for JEV in Jinshan, Shanghai was 4.52/1,000 (range 0.80–14.64). Hence, there is a potential risk of a JEV epidemic in that region.ConclusionGI-b is the dominant circulating JEV genotype in nature and poses a health risk to animals and humans. The potential threat of widespread GETV distribution as a zoonosis is gradually increasing. The present study also disclosed the dispersion and host range of ISFVs. These findings highlight the importance of tracing the movements of the vectors and hosts of mosquito-borne pathogens in order to prevent and control arbovirus outbreaks in China.
Highlights
A total of 29,285 mosquitoes including Anopheles sinensis, Culex spp., Aedes albopictus, and Armigeres subalbatus were collected at the seven sentinel sites during the mosquito activity season of 2018
Forty-eight flavivirus and five Getah virus (GETV) strains were recovered by successful amplification of the partial flavivirus NS5 and the alphavirus NSP1 gene, respectively
This work research reports for the first time the presence of Aedes flavivirus (AeFV), Chaoyang virus (CHAOV), Culex flavivirus (CxFV), Quang Binh virus (QBV), and Yunnan Culex flavivirus (YNCxFV) at multiple sentinel sites
Summary
Dengue outbreaks have occurred in China over the last decade. These occurred in Yunnan [2013, (Zhang et al, 2014)], Guangdong [2014, (Xiao et al, 2016)], Fujian [2016, (Han et al, 2018)], and Zhejiang [2017, (Yan et al, 2018)] and of them emerged in heretofore dengue-free or low endemic areas. Morbidity was 1.63/100,000 and was second in severity only to that of the major dengue outbreak of 2014 (Liu, 2020). Summer monsoons and climate change have substantial impacts on dengue control and prevention in southeastern China (Liu et al, 2020a). Increases in global travel and trade are changing arbovirus distributions worldwide. Arbovirus surveillance in field-collected mosquitoes may provide early evidence for mosquito-borne disease transmission
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