Objective To investigate the population density of Anopheles vector of malaria after elimination of malaria in Hangzhou, China, and to provide a basis for risk assessment of imported malaria transmission and development of control strategy. Methods Ten districts, counties, or cities in Hangzhou were selected as malaria vector monitoring sites from 2018 to 2019. The density of adult (malaria vector) and larval mosquito populations were monitored by lamp-trapping, human-trapping, and dip survey methods. The data of confirmed cases of vivax malaria in Hangzhou from 2016 to 2020 were collected. The characteristics of malaria vector and epidemic were analyzed. Results A total of 1 686 mosquitoes were captured by lamp-trapping from 2018 to 2019. Of malaria vectors, only An. sinensis (116, 6.88%) was captured in the suburb and rural areas. A total of 834 An. sinensis adults were captured by human-trapping. The density was the highest in late July, which was 0.56 mosquitoe/person-hour in suburb areas and 5.63 mosquitoes/person-hour in rural areas (20.50 mosquitoes/person-hour in Chun'an county). Only 373 An. sinensis larvae were captured by dip survey in rice fields, with the density of 0.70, 0.05, and 0.02 larva/dip in Chun'an county, Tonglu county, and Lin'an district, respectively. The density of larvae was the highest in late July (0.54 larva/dip on average). From 2016 to 2020, 12 imported cases of vivax malaria were reported in Hangzhou, mainly in Yuhang district and Xihu district. The mean time from onset to diagnosis was (7.08±8.24) d. Conclusion An. sinensis is the only malaria vector consistently present in Hangzhou, which is mainly found in rural areas and varies significantly across seasons. Undetected imported cases of vivax malaria still pose a risk of transmission in Hangzhou.
ZHU Su-juan, JIN Xing-yi, XU Wei-min, WEI Ling-ya, SUN Zhou, KONG Qing-xin, CHEN Jun-fang
. An analysis of the population density of Anopheles sinensis as malaria vector after elimination of malaria in Hangzhou, China[J]. Chinese Journal of Vector Biology and Control, 2021
, 32(5)
: 546
-550
.
DOI: 10.11853/j.issn.1003.8280.2021.05.007
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