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Attractive action of different chemical substances for Aedes albopictus
Fei WANG, Hao-di XU, Xin LI, Pei-en LENG, Hong-xia LIU
Abstract281)   HTML    PDF (854KB)(796)      

Objective: To select chemical substances with attractive effects on Aedes albopictus for on-field assessment, and to explore the preference of Ae. albopictus to six human odors. Methods: Under laboratory conditions, six chemical substances (1-octen-3-ol, lactic acid, myristic acid, ammonia, acetone, and ethyl acetate) were separately tested for their individual attracting effects on female Ae. albopictus at concentrations of 0.1, 1.0, and 10.0 mg/ml. The six substances were mixed in pairs (1∶1) at certain concentrations, and then the pairs were tested for attracting effects on female Ae. albopictus. The pair with good attractive effects was combined with lactic acid for testing. The attractant combination selected by laboratory experiments was tested for attractive action for Ae. albopictus in the field. The attracting effects of the substances or combinations on Ae. albopictus were compared using the t test and one-way analysis of variance. Results: Ae. albopictus mosquitoes were attracted to 1-octen-3-ol at 0.1, 1.0, and 10.0 mg/ml, myristic acid at 1.0 and 10.0 mg/ml, and ethyl acetate at 0.1 mg/ml, but not to the other three substances at any concentration. The pairs of 1-octen-3-ol+myristic acid, lactic acid+myristic acid, and lactic acid+1-octen-3-ol statistically attracted Ae. albopictus compared with the control group (t=8.102, P=0.001; t=4.696, P=0.009; t=5.127, P=0.007). The combination of lactic acid+1-octen-3-ol+myristic acid statistically attracted Ae. albopictus compared with the control group (F=86.841, P < 0.001). Field testing showed significant differences in the attracting effect between lactic acid+1-octen-3-ol+myristic acid and the control (day 1: t=7.462, P=0.014; day 2: t=20.500, P < 0.001; day3: t=9.383, P=0.001). Conclusion: The combination of lactic acid, 1-octen-3-ol, and myristic acid has attractive action for Ae. albopictus, which should be further researched in the field.

2023, 34 (4): 447-450, 496.   doi: 10.11853/j.issn.1003.8280.2023.04.001
Distribution of knockdown resistance genotypes in Aedes albopictus in Nanning, Guangxi Zhuang Autonomous Region, China, 2022
Xue LI, Feng LING, Shu-lin WEI, Zhi-qiang QU, Shu-qin DIAO, Yan-cui HUANG, Mi-fang LUO
Abstract237)   HTML    PDF (596KB)(645)      

Objective: To investigate knockdown resistance (kdr) genotypes of Aedes albopictus which is the major vector of dengue in Nanning, so as to understand their insecticide resistance levels and provide evidence for scientific control of Ae. albopictus. Methods: Ae. albopictus larvae were collected using the dip method in Nanning and raised to adults in the laboratory. After morphological identification, Ae. albopictus mosquitoes were soaked in 75% ethanol and stored at -20 ℃. DNA was extracted from individual mosquitoes using the magnetic bead-based method. The partial fragments of the voltage-gated sodium channel (VGSC) gene were amplified by PCR and sequenced for alignment with the Basic Local Alignment Search Tool on the platform of National Center for Biotechnology Information. DNAStar 7.1 was used to analyze single-site and multiple-site mutations in the confirmed VGSC gene of Ae. albopictus mosquitoes. Results: A total of 175 Ae. albopictus mosquitoes were examined in 2022, obtaining 350 sequences (about 400 bp in length). Mutations were detected at the 1016 and 1534 loci but not at the 1532 locus of the VGSC gene. At the 1016 locus, there were two alleles (wild-type V [148, 78.28%] and mutant G [49, 21.72%]) and three genotypes (wild-type homozygote V/V [126, 72.00%], mutant homozygote G/G [27, 15.43%], and wild-type/mutant heterozygote V/G [22, 12.57%]). At the 1532 locus, there was one allele (wild-type I [175, 100%]) and one genotype (wild-type homozygote I/I [175, 100%]). At the 1534 locus, there were three alleles (wild-type F [51, 16.86%], mutant S [116, 36.29%], and mutant C [135, 46.85%]) and six genotypes (wild-type homozygote F/F [8, 4.57%], wild/mutant heterozygotes F/S [21, 12.00%] and F/C [22, 12.57%], mutant heterozygote S/C [64, 36.57%], and mutant homozygotes S/S [21, 12.00%] and C/C [39, 22.29%]). Conclusion: VGSC gene mutations are frequent in Ae. albopictus in Nanning. Attention should be paid to the insecticide resistance levels of Ae. albopictus for scientific, standardized, and efficient use of insecticides.

2023, 34 (4): 480-484.   doi: 10.11853/j.issn.1003.8280.2023.04.007
An analysis of ecological surveillance results of dengue vector Aedes albopictus in Hangzhou, Zhejiang Province, China, 2017-2021
Bin-bin JIN, Ling-ya WEI, Hui JIN, Yang CAO, Ying-hong WANG, Qing-xin KONG
Abstract232)   HTML    PDF (747KB)(831)      

Objective: To investigate the density distribution of Aedes mosquitoes in different habitats and seasonal fluctuation in Hangzhou, Zhejiang Province, China from 2017 to 2021, so as to provide a scientific basis for effective prevention and control, risk assessment, and early warning of dengue fever. Methods: According to the National Vector Surveillance Implementation Plan and the Zhejiang Provincial Vector Surveillance Plan, Aedes mosquitoes were monitored in 15 districts (counties and cities) in Hangzhou. Adult mosquitoes were monitored using the double-layered mosquito net method, and larvae were monitored using the Breteau index (BI) method. The surveillance time was set during April to November. The mosquito surveillance data of the 15 districts (counties and cities) were collected. Excel 2019 software was used for data analysis. The net trap index, BI, and container index (CI) were calculated. Categorical data were compared using the Chi-squared test. One-way analysis of variance was used for quantitative data. Results: From 2017 to 2021, the density of Ae. albopictus in Hangzhou by the double-layered mosquito net method was 2.54 mosquitoes/net·h, and no Ae. aegypti mosquitoes were captured. The density of adult mosquitoes was lowest in 2017 and highest in 2020. There was a statistical difference in the net trap index between different years (F=5.117, P=0.017). The seasonal distribution generally presented a bimodal pattern, with the peaks of mosquito densities mainly in July and October. The average BI from 2017 to 2021 was 9.18, and the peak period of the BI was during May to October. The CI showed that Ae. albopictus larvae were distributed in all kinds of water bodies. The CI differed statistically between different water bodies in the same year (all P < 0.001) and between different years in the same water body (all P < 0.001). Conclusions: Ae. albopictus density was high in Hangzhou, indicating a risk of dengue fever outbreaks and regional epidemics. It is recommended that the counties (cities, districts) take timely mosquito control measures according to the density, distribution, and seasonal fluctuation of mosquitoes.

2023, 34 (4): 491-496.   doi: 10.11853/j.issn.1003.8280.2023.04.009
Surveillance and analysis of flies in Fengxian District, Shanghai, China, 2011-2021
Bin GE, Hai-bing ZHANG, Hong-xia LIU, Ying ZHOU, Qing LIU, Ke-hua YI, Tao HUANG
Abstract217)   HTML    PDF (812KB)(631)      

Objective: To analyze the species, composition, density, distribution, and seasonal fluctuation of flies in Fengxian District, Shanghai, China, so as to provide a basis for the prevention and control of flies in Fengxian District. Methods: The fly surveillance data in Fengxian District, Shanghai from 2011 to 2021 were collected, and Excel 2013 was used to summarize and analyze of the data. The Kolmogorov-Smirnov test was used to compare the density of flies in different habitats. Results: From 2011 to 2016, there was no significant change in the population density of flies in Fengxian District, ranging from 0.50 to 1.02 flies per cage of average annual density. In 2017 and 2018, the density of flies (1.76 and 5.25 flies per cage, respectively) increased significantly, by 70.87% and 409.71%, respectively, compared with 1.03 flies per cage in 2015. The fly density decreased year by year in 2019 and 2020, and increased in 2021, second only to the peak density in 2018. A total of 2 996 adult flies were captured, with an average density of 2.02 flies per cage. Muscina stabulans was the main species (accounting for 31.38%), followed by Boettcherisca peregrina (accounting for 28.64%). The flies density in large-scale green belts was highest with 2.32 flies per cage. The density of flies reached its peak in June, dropped sharply from July to August, and steadily decreased from September to November. Conclusions: There are more flies in large-scale green belts of Fengxian District, and the fly density peaks in June. The critical period to prevent fly-borne diseases is before June. Relevant departments in Fengxian District should raise and strengthen awareness of fly control. The environment management of large-scale green belt should be strengthened to reduce the breeding environment of flies.

2023, 34 (4): 462-466.   doi: 10.11853/j.issn.1003.8280.2023.04.004
Establishment of a duplex droplet digital PCR assay for Japanese encephalitis and West Nile viruses
ZHANG Jun-feng, ZHANG Ya-li, WANG Rui-chen, LU Yang, ZHANG Tian-zi, FU Shi-hong, YIN Qi-kai, LI Fan, HE Ying, NIE Kai, MA Chao-feng, LIANG Guo-dong, HU Rui-ping, XU Song-tao, WANG Huan-yu
Abstract182)      PDF (1462KB)(923)      
Objective To establish a duplex droplet digital polymerase chain reaction (ddPCR) detection method for Japanese encephalitis virus (JEV) and West Nile virus (WNV). Methods Based on the designed primers and probes of JEV and WNV, a duplex ddPCR detection system for JEV and WNV was established. Its sensitivity, specificity, and repeatability were explored. The sensitivity was compared with the number of cycles required for the fluorescent signal to cross the threshold in each reaction tube of dual quantitative PCR. Results The detection sensitivity of the duplex ddPCR detection system could reach 10 2 copies/μl for both JEV and WNV, with good specificity and repeatability. No cross-reactivity was observed with the Dengue virus, Chikungunya virus, Zika virus, Tick-borne encephalitis virus, and human genome. Conclusion The established duplex ddPCR method shows high sensitivity and specificity for JEV and WNV detection, which provides a solution for detection for the two viruses in different scenarios.
2023, 34 (3): 285-290.   doi: 10.11853/j.issn.1003.8280.2023.03.001
Analysis of mosquito surveillance in Guizhou province,China,2017-2021
ZHANG Yan, ZHOU Jing-zhu, WANG Dan, SHI Wei-fang, XIANG Yu-long, HU Yong, LIANG Wen-qin
Abstract181)      PDF (2287KB)(800)      
Objective To investigate the species composition, population density, and seasonal fluctuation of mosquitoes in human settlements and surrounding environments in Guizhou province, China, and to provide a basis for risk assessment of mosquito-borne diseases and scientific and effective vector control. Methods Mosquito surveillance data from 78 provincial vector surveillance sites in Guizhou province from 2017 to 2021 were collected to analyze mosquito species composition and compare mosquito population density and seasonal fluctuations in different years, regions, and habitats. SPSS 24.0 software was used to perform analysis of variance on the Breteau index (BI) and density of mosquitoes in different habitats for risk assessment. Results A total of 131 476 female mosquitoes were captured from 2017 to 2021, with a density of 5.82 mosquitoes/light·night. Culex pipiens quinquefasciatus accounted for the highest proportion with 43.34% of the total catches, followed by Anopheles sinensis with 20.68%. Cx. pipiens quinquefasciatus was the dominant mosquito species in most cities/prefectures. Zunyi had the highest composition ratio of Cx. pipiens quinquefasciatus with a total of 17 409 catches (61.32%). There was a statistical difference in mosquito density in different areas ( F=5.276, P<0.001). From 2017 to 2021, the highest densities of mosquitoes were all in livestock sheds, and Cx. pipiens quinquefasciatus was the dominant mosquito species in all habitats. The density of mosquitoes was statistically different in different habitats ( F=114.368, P<0.001). Adult mosquito density by light trapping increased gradually from May, peaked during June to August, and decreased rapidly from September. BI showed two obvious peaks in June and August, respectively. The BI began to rise rapidly in May, and gradually declined in September and October. The BI was greater than 5 for each year. The areas of level-1 risk included Anshun, Guiyang, and Qiandongnan Miao and Dong Autonomous Prefecture. The BI values in Anshun in 2019 and Guiyang in 2021 were both greater than 10, indicating a level-2 risk. Conclusions Cx. pipiens quinquefasciatus and An. sinensis are the dominant mosquito species in human settlements and surrounding environments in Guizhou province. The mosquito density is high in rural habitats, especially in livestock sheds, which are major mosquito breeding sites, and mosquito control should be strengthened in such environments. The peaks of mosquito activity in Guizhou province are in June and August, which may by closely related to the unique climate and rainfall conditions of Guizhou province. Mosquito control should be done before the peak breeding season of mosquitoes to reduce the density of mosquitoes and the risk of mosquito-borne virus transmission.
2023, 34 (3): 356-361.   doi: 10.11853/j.issn.1003.8280.2023.03.013
Vector surveillance and control evaluation in 7th Military World Games in Wuhan, Hubei Province, China
Liang-cai ZHOU, Zhong-jin ZHOU, Ying WANG, Tai-ping WU, Li-qun WU, Wei-feng TANG
Abstract172)   HTML    PDF (521KB)(663)      

Objective: To analyze the situation of vector control in the 7th Military World Games in 2019, so as to provide a scientific basis for vector control in similar major events in the future. Methods: The surveillance results of major vectors in different types of places (venues, hotels, designated hospitals, etc.) in urban areas of Wuhan, China from June to September 2019 were analyzed. Excel 2007 and SPSS 23.0 softwares were used for data processing. The Chi-squared test and Fisher's exact test were used for data analysis. Results: In June, the positive rate of fly breeding sites, the infestation rate of nymph and adult cockroaches, and the detection rate of cockroach eggs were highest, which were 3.88%, 1.69%, and 0.06%, respectively. In July, the positive rate of indoor rodent trace, mosquito larval route index and dip index, and indoor fly density were highest, which were 2.91%, 1.31 stagnant waters per km, 4.20%, and 4.81%, respectively; the qualified rates of rodent-proof and fly-proof facilities were lowest, which were 85.97% and 87.84%, respectively. In August, the outdoor rodent density route index and adult mosquito landing index were highest, which were 1.04 rodents and 1.63 mosquitoes per person, respectively. Conclusions: Authorities should continuously monitor vector infestation and control effects in key places of Wuhan Military World Games, scientifically and effectively evaluate the implementation of vector control, and timely detect relevant problems and adjust response strategies to prevent the occurrence of emergencies.

2023, 34 (4): 485-490.   doi: 10.11853/j.issn.1003.8280.2023.04.008
Lethal effects of recombinant CYP307A1 RNAi Chlorella by feeding on Aedes albopictus
HUANG Xiao-dan, XIAO Sa, HE Chang-hao, LI Zhi-jie, ZHANG Xiu-xia, LI Ya-jun, FEI Xiao-wen, DENG Xiao-dong
Abstract170)      PDF (3280KB)(745)      
Objective To investigate the effects of silencing the ecdysone synthesis pathway enzyme gene CYP307A1 of Aedes albopictus on the growth and development of Aedes larvae, and to provide new ideas for the prevention and control of mosquito-borne infectious diseases. Methods An RNAi expression vector targeting CYP307A1 was constructed using RNAi technology. Chlorella was used as the recipient for electrotransformation. The selected recombinant Chlorella strains were fed to Ae. albopictus larvae. WPS 2020 software was used to pool data on the mortality, pupation rate, emergence rate, body length, and quantitative real-time PCR results of the expression of CYP307A1 gene in larvae. One-way analysis of variance was performed on the mean values of all groups using SPSS 25. Origin 2019 and WPS 2020 were used to make charts. Results The 300-mosquito experiment showed that the mortality rates of larvae in the control groups fed with filtered water, feed, wild Chlorella, and Chlorella transferred with pMaa7/IR vector were 1.50%, 0.17%, 0.83%, and 8.00%, respectively; the mortality rate of larvae fed with recombinant CYP307A1 RNAi Chlorella was 80.33%, which was statistically higher than that of the control groups ( P<0.05). The pupation rate and emergence rate of Aedes larvae fed with feed were 99.83% and 98.50%, respectively, while those of the group fed with recombinant CYP307A1 RNAi Chlorella were 18.50% and 98.50%, respectively. The pupation rate and emergence rate with recombinant CYP307A1 RNAi Chlorella were statistically lower than those of the control group ( P<0.05). The expression of the CYP307A1 gene in Aedes larvae fed with the recombinant Chlorella was decreased by 79.00% compared with the control group ( P<0.01). Conclusion Recombinant CYP307A1 RNAi Chlorella has anti-mosquito function, which shows promise in the field of biological mosquito control.
2023, 34 (3): 336-343.   doi: 10.11853/j.issn.1003.8280.2023.03.010
Epidemiological characteristics of hemorrhagic fever with renal syndrome and host animal surveillance in Zhejiang province, China, 2021
SU Fan, SUN Ji-min, LING Feng, ZHANG Rong, LIU Ying, WANG Zhen
Abstract169)      PDF (1590KB)(771)      
Objective To analyze the epidemic situation of hemorrhagic fever with renal syndrome (HFRS) and the populations distribution and Hantavirus infection status of the host animals in Zhejiang province, China in 2021, and to provide scientific evidence for establishing preventive measures. Methods Descriptive epidemiological methods were used to analyze HFRS case data and host surveillance data, which were online reported in the Communicable Disease Surveillance Information Reporting and Management System of Zhejiang province in 2021. The Chi-square test was used for rate comparison. Results A total of 180 HFRS cases were reported in Zhejiang province in 2021, with a mean annual incidence rate of 0.29/100 000. Most cases were observed in Taizhou, Ningbo, Shaoxing, and Quzhou. The cases distributed throughout the year, peaking during May to June in summer and December in winter at similar levels. The high-incidence group aged over 40 years old, accounting for 76.67% (138/180) of the total cases. The main occupation was farmers, accounting for 61.67%. A total of 11 921 effective traps were set in the five surveillance sites in Zhejiang province, capturing 660 small mammals, with an average capture rate of 5.54%. A total of 660 serum samples of small mammal were detected, among which 35 (5.30%) were antibody-positive. Hantavirus was positive in 15 of 660 (2.27%) small mammal lung samples. There were statistical differences in capture rate ( χ 2=16.161, P<0.05), the positive rate of HFRS antibody ( χ 2=14.957, P=0.005), and the virus infection rate of small mammals ( χ 2=8.413, P=0.048) among the five surveillance sites. Conclusions HFRS was sporadic at a low level and distributed in extensive areas in Zhejiang province in 2021. The surveillance sites had generally high small mammal densities and fluctuating virus infection rates in small mammals, requiring scientific rodent control-based comprehensive prevention and control measures.
2023, 34 (3): 378-382.   doi: 10.11853/j.issn.1003.8280.2023.03.016
Epidemiological characteristics of typhus fever in Jinzhai County, Anhui Province, China, 2013-2022
DING Jun-fei, GUAN Peng-cheng, LI Wei
Abstract168)   HTML    PDF (825KB)(239)      
Objective To analyze the epidemiological characteristics of typhus fever in Jinzhai County, Anhui Province, China in recent ten years, so as to provide a basis for scientific control of typhus fever. Methods The descriptive epidemiological method was used to systematically analyze the characteristics of the surveillance data on cases of typhus fever in Jinzhai County from 2013 to 2022 collected from the China Information System for Disease Control and Prevention. Qualitative data were described as rates or constituent ratios, and analyzed using the Chi-squared test. Results From 2013 to 2022, 426 cases of typhus fever were reported in Jinzhai County, with a mean annual incidence of 8.23/100 000, and no deaths were reported. The incidence peak occurred between April and September (spring and summer), during which the number of cases accounted for 85.68% (365/426) of the total number of cases reported. The incidence of typhus fever was significantly higher among women than among men ( χ 2=30.878, P<0.001), and the male-to-female ratio was about 0.62:1. The incidence of typhus fever was highest in the age group of 60-<70 years (256.67/100 000). A vast majority of cases were farmers among occupations (93.90%). Cases were reported in 22 of 23 townships. Conclusions Cases of typhus fever were widely reported across Jinzhai County, predominantly affecting farmers and middle-aged and elderly people, with significant sex difference and seasonality. Therefore, typhus fever surveillance, prevention, and control should be strengthened for high-incidence areas and high-risk populations.
2023, 34 (6): 767-771.   doi: 10.11853/j.issn.1003.8280.2023.06.011
Rodent and pathogen surveillance results in Zunyi, Guizhou Province, China, 2022
De-yang ZHENG, Lin ZHU, Wen-qin LIANG, Jia HUANG, Wei-fang SHI, Kai RAO, Jing-zhu ZHOU, Cai-xia XIA
Abstract159)   HTML    PDF (636KB)(737)      

Objective: To investigate the rodents species, density, and pathogens they carry in Zunyi, Guizhou Province, China. Methods: A total of 70 sampling points were set in 14 counties/districts of Zunyi, with five points in the east, south, west, north, and center of each county/district. Small mammals were monitored through night trapping in Zunyi from October 2021 to October 2022, followed by species identification and pathogen detection. Excel 2021 was used for data organization. SPSS 26.0 was used to analyze the density, species, and pathogen-carrying status of small mammals through rate or constituent ratio comparison with the Chi-square test (P < 0.05 indicates a statistically significant difference). Results: A total of 9 969 effective traps were placed at all the surveillance points, capturing 549 small mammals in total, of which 522 were rodents. The total density of small mammals was 5.51%. The total density of rodents was 5.24%. The rodent density was highest in Honghuagang District (12.94%), followed by Fenggang County (12.34%), and lowest in Chishui City (1.80%). There was a statistical difference in rodent density between the counties/districts (χ2=195.619, P < 0.001). Rattus norvegicus was the dominant rodent species in urban residential areas, rural residential areas, and key industries, while Apodemus agrarius was the dominant species in farming areas. The composition of rodent species statistically differed in different regions (the center, north, east, and west) of Zunyi (χ2=117.357, P < 0.001). Each small mammal was examined for Leptospira interrogans and Orientia tsutsugamushi in the liver, spleen, and kidney; Dabie bandavirus in the liver, spleen, and lung; and Hantavirus in the lung. Among 343 samples tested, 27 were positive, all for L. interrogans, with a pathogen detection rate of 7.87%. Shrews had the highest detection rate (16.00%), followed by A. agrarius (12.35%), and R. norvegicus had the lowest detection rate (1.64%). There was a significant difference in the detection rates of different species of small mammals (χ2=14.372, P=0.002). The detection rate was 9.66% (26/269) in farming areas, which was highest, and 2.94% (1/34) in key industries, with negative detection results in urban and rural residential areas. There were no differences in detection rates between different habitats (χ2=5.171, P=0.160). The detection rate was 27.03% in Meitan County, followed by 25.00% in Suiyang County, and zero in Renhuai City, Fenggang County, and Yuqing County, with a statistical difference between different counties/cities/districts (χ2=35.409, P=0.001). Conclusions: The density of rodents was relatively high in Zunyi. The detection of L. interrogans should be a warning of the possibility of related diseases. Local authorities should strengthen rodent control in spring and autumn and take comprehensive control measures according to actual situation and dominant rodent species and pathogen detection status in different habitats, so as to reduce the density of rodents and prevent the occurrence of rodent-borne diseases.

2023, 34 (4): 501-507.   doi: 10.11853/j.issn.1003.8280.2023.04.011
Distribution and seasonal fluctuation of sandflies in Shanxi province, China
TIAN Xiao-dong, DAI Pei-fang, ZHAO Jun-ying, DONG Hai-yuan, CHENG Jing-xia
Abstract157)      PDF (3474KB)(758)      
Objective To investigate the species, distribution, density, and seasonal fluctuation of sandflies in different areas of Shanxi province, China, and to provide a scientific basis for the risk assessment and control of kala-azar. Methods From May to September in 2021, sandflies were captured with light trapping in different habitats in 14 counties/cities/districts of 11 prefectures of Shanxi province. The non-bloodsucking female sandflies were randomly selected from different areas and identified by morphological and molecular biological methods. Excel 2010 software was used to construct the database, followed by analysis of sandfly catches by habitat or month. The distribution of sandflies was mapped using ArcGIS 10.7. Results A total of 19 006 sandflies were captured, with an average density of 40.87 sandflies/light·night. The seasonal fluctuation of sandflies throughout the year showed a single-peak distribution. Sandflies were first caught in the first half of May, and the density peaked during the second half of June to the first half of July, after which the density decreased rapidly. Sandflies were captured in six environmental types: farmyards, sheep pens, cattle sheds, chicken pens, pig pens, and mule/horse sheds. Sheep pens had the highest density of 121.39 sandflies/light·night, and farmyards had the lowest density of 9.63 sandflies/light·night. Of the 432 sandflies identified by morphology, one was Sergentomyia squamirostris, and the rest were Phlebotomus chinensis. Another 110 sandflies were randomly selected for molecular biological identification: four were S. squamirostris, and the remaining 106 were P. chinensis. P. chinensis was the absolute dominant species. Conclusions Sandflies distributed in all the 14 counties/cities/districts of the 11 cities of Shanxi province. P. chinensis was the dominant species of sandflies in Shanxi province, which was the main vector for kala-azar transmission. They were mainly distributed in rural areas, especially in livestock/poultry-raising places, where environmental management and sandfly control should be strengthened to reduce the risk of kala-azar transmission.
2023, 34 (3): 417-421.   doi: 10.11853/j.issn.1003.8280.2023.03.023
Expression and purification of Hq012 gene of Haemaphysalis qinghaiensis in Escherichia coli
MA Jing, CHEN Kai-ting, GUANG Hui, ZHAO Wen-bin, YANG Yin-ran, GAO Jin-liang, CAO Mei-na
Abstract157)   HTML    PDF (4936KB)(265)      
Objective To optimize the conditions for the induction expression and purification of recombinant Hq012 (rHq012) inclusion bodies of Haemaphysalis qinghaiensis. Methods The novel gene Hq012 with no homogenous sequences in the GenBank database was cloned from the cDNA expression library of H. qinghaiensis to be transfected into Escherichia coli Rosetta (DE3) using the prokaryotic expression plasmid pET-30a-Hq012. Isopropyl-β-D-thiogalactoside (IPTG) was used to induce the expression of rHq012 protein. After homogenizing the bacteria under high pressure, the inclusion bodies were dissolved in 6 mol/L guanidine hydrochloride solution. We compared the yield of the target protein obtained by first renaturation and then purification (refolding by dilution followed by purification with nickel ion affinity chromatography) and by first purification and then renaturation (purification with nickel ion affinity chromatography followed by refolding by dialysis). The obtained protein was identified by 12% sodium dodecyl sulfate polyacrylamide gel electrophoresis. Results The nucleotide sequence length of the Hq012 gene was 759 bp, containing an open reading frame of 486 bp, encoding a protein with a relative molecular mass of 18 500. The protein expression was the highest at 8-hour induction with IPTG at 0.1 mmol/L. The inclusion bodies were dissolved with 6 mol/L guanidine hydrochloride. The yield of rHq012 harvested by first renaturation and then purification was higher compared with that by first purification and then renaturation. The relative molecular mass of the protein purified by nickel ion affinity chromatography was about 17 000, which was consistent with expected results. Conclusions Induction at an concentration of 0.1 mol/L IPTG for 8 hours was the best induction condition, and the method of first refolding followed by purification was an optimal purification method for the tick-derived recombinant protein rHq012. The study provides a reference for the purification of inclusion body protein.
2023, 34 (6): 713-718.   doi: 10.11853/j.issn.1003.8280.2023.06.001
An analysis of fly ecological surveillance results in Shanghai, China, 2016-2021
Jing-jing WANG, Jing-qiu XU, Jiang ZHU, Hong-xia LIU, Pei-en LENG
Abstract150)   HTML    PDF (799KB)(756)      

Objective: To analyze the species, density, distribution, and variation of flies in Shanghai, China, to carry out risk assessment, prediction, and early warning of fly-borne diseases in a timely manner, so as to provide scientific reference for fly control. Methods: Using the cage trap method, fly traps were placed in farmers' markets, residential areas, external environment of restaurants, and large green belts. Fly surveillance data were collected every ten days from March to November in 2016-2021 in Shanghai. The data were processed and analyzed using Excel 2019 and SPSS 20.0. Results: From 2016 to 2021, 18 052 flies were caught with an average density of 1.52 flies/cage. The identified fly species belonged to 5 families, 9 genera, and 14 species. The dominant species were Muscina stabulans, Boettcherisca peregrina, Chrysomya megacephala, Lucilia sericata, and Musca domestica. M. stabulans showed the highest density of 0.28 flies/cage, followed by B. peregrina (0.24 flies/cage). In large green belts, the density of B. peregrina was higher than that of M. stabulans, and in all other habitats, the density of M. stabulans was the highest. There was a significant difference in density between B. peregrina and M. stabulans in the farmers' market (t=-2.674, P=0.023). The proportion of Mu. domestica decreased year by year, and the proportion of M. stabulans increased. The fly density was the highest in 2018 (1.82 flies/cage) and the lowest in 2016 (1.04 flies/cage). Fly density peaked from June to August, with the monthly average densities of 2.65, 2.49, and 2.28 flies/cage, respectively. In 2016-2021, the fly density in different habitats was in the order of farmers' markets > large green belts > residential areas > external environment of restaurants. Conclusions: The fly species are diverse in Shanghai. M. stabulans has the highest density. Fly density peaks from June to August, and farmer's market is a key place for targeted fly control. Fly density rose again after decline in 2019, suggesting that comprehensive control of flies should be continuously strengthened.

2023, 34 (4): 457-461.   doi: 10.11853/j.issn.1003.8280.2023.04.003
Host animal investigation and etiological analysis of Hantavirus in some areas of Zhoushan Islands, Zhejiang province, China, 2021
CHAI Neng-ming, TAN Qi-long, SHU Ji-wei, YE Ling, ZHANG Tong-Jie, LI Shi-bo, ZHANG Sen
Abstract147)      PDF (1914KB)(774)      
Objective To investigate the population distribution, virus-carrying status, and virus gene characteristics of host animals for Hantavirus in some areas of Zhoushan Islands, Zhejiang province, China, and to provide evidence for prevention and control of hemorrhagic fever with renal syndrome (HFRS). Methods Small mammals were captured using the night trapping method in Dinghai and Daishan areas of Zhoushan Islands, followed by species identification. The rodent density and species composition were analyzed using the Chi-square test. The small mammal’ lungs were collected to detect the nucleic acid of Hantavirus by quantitative real-time PCR. The M gene was amplified by nested PCR and sequenced for genotyping and homology analysis. Results In Dinghai and Daishan areas of Zhoushan Islands in 2021, the average rodent density was 3.42%, with 1.71% in the wild and 6.16% in residential areas. Six species of small mammals were captured. The dominant species was Apodemus agrarius in the wild and Rattus norvegicus in residential areas. The density of rodents was statistically different between Daishan Island, Yushan Island, and Dinghai Island ( χ 2=108.468, P<0.001), between the wild and residential areas ( χ 2=68.935, P<0.001), and between different species ( χ 2=37.749, P<0.001). Hantavirus RNA was detected in 13 small mammals lung specimens, with a positive rate of 6.70%. The M fragments of three Hantavirus RNA extracts were successfully amplified and sequenced. The homology of the three M fragments was 96.90%-97.10%, belonging to Seoul virus (SEOV, S3 subtype). Conclusions There are HFRS foci with R. norvegicus as the source of infection in Zhoushan Islands, where SEOV S3 subtype is the epidemic strain. Environmental changes may alter natural foci.
2023, 34 (3): 326-330.   doi: 10.11853/j.issn.1003.8280.2023.03.008
A comparative study based on gridded mosqito oviptrap method and human landing catch method monitoring Aedes mosquitoes
Hong CHEN, Zhou ZHOU, Hong-xia LIU
Abstract145)   HTML    PDF (5093KB)(700)      

Objective: To explore the factors affecting Aedes surveillance by the mosquito ovitrap method in a grid mode, so as to provide a scientific basis for the surveillance and control of Aedes mosquitoes and related mosquito-borne infectious diseases. Methods: Three adjacent residential areas with similar areas, building ages, and greenery ratios were selected as surveillance points in Jing'an District, Shanghai, China. Each residential area was divided into secondary surveillance blocks (about 90 m × 60 m) in a 3×3-grid mode. On-site monitoring was conducted in each surveillance block using the mosquito ovitrap method and the human landing catch method, three times one month from July to September 2021. By comparing the surveillance results of different residential areas, different surveillance blocks, and different environmental characteristics, the factors influencing the positive rate of the mosquito ovitrap method were determined. Excel 2016 and SPSS 16.0 were used to process the data. The Kruskal-Wallis rank sum test, tow-way analysis of variance, and Spearman correlation analysis were performed. Results: A total of 30 secondary surveillance blocks were designated. Eight times of surveillance were completed, and 131 mosquito ovitraps were set each time. The mosquito ovitrap index (MOI) in residential areas 1, 2, and 3 were 8.71, 12.38, and 11.97, respectively, with no significant difference (χ2=2.750, P=0.253). There were significant differences in the MOI among different blocks of residential areas 1 and 2 (F=2.135, P=0.047; F=2.168, P=0.044). In residential areas, the positive rate was 12.24 in living areas and 5.76 in community school areas, with a significant difference (χ2=6.657, P=0.010). The MOI was 14.10 for green areas on the house side, 8.87 for concentrated green areas, and 7.98 for green areas on the road side, with a significant difference (χ2=8.372, P=0.015). During the surveillance period, the MOI was 13.28 when the days of rainfall was < 2 d, and 8.79 when the days of rainfall was ≥2 d, with a significant difference (χ2=4.218, P=0.047). In residential area 1, the average MOI was 8.69, and the average landing index was 3.33 mosquitoes/person·h. In residential area 2, the average MOI was 12.45, and the average landing index was 8.58 mosquitoes/person·h. In residential area 3, the average MOI was 11.88, and the average landing index was 6.50 mosquitoes/person·h. The ratio of the MOI to the landing index was distributed between 1∶1 and 3∶1. Pearson correlation analysis showed that the MOI was highly correlated with the human landing index in each block (r=0.549, P=0.005). Conclusions: The density of Aedes mosquitoes may differ greatly in different areas of large residential areas due to differences in greening types, functional zoning, and other factors. The mosquito ovitrap method has the advantages of simple operation and high specificity compared with other surveillance methods for Aedes mosquitoes, and it is highly consistent with the human landing catch method. The mosquito ovitrap method with grid-based surveillance point distribution can be used in actual practice, which can effectively avoid deviations caused by point selection and fully reflect the density of Aedes mosquitoes.

2023, 34 (4): 451-456.   doi: 10.11853/j.issn.1003.8280.2023.04.002
An analysis of cockroach infestation and its intestinal pathogens in catering places in Pudong New Area, Shanghai, China
Jun LIU, Chen LIN, Yong-ting YUAN, Si-yu YU, Jing-yi LIU, Hui-hui LI, Lei FENG, Ying-pei GU, Han-zhao LIU
Abstract138)   HTML    PDF (729KB)(639)      

Objective: To analyze cockroach infestation and its intestinal pathogen infection status in catering places in Pudong New Area, Shanghai, China, so as to provide scientific suggestions for cockroach control and the prevention and control of infectious diarrhea in catering places. Methods: From April 2021 to March 2022, cockroach infestation survey and sampling were conducted using cockroach traps in five types of catering places in 12 subdistricts and towns of Pudong New Area in the middle of each month. The captured cockroaches were examined for intestinal pathogens. Excel 2019 and SPSS 22.0 were used for data collation and statistical analysis. Results: In the catering places of Pudong New Area, the cockroach infestation rate was 20.83%, and the cockroach density was 0.74 cockroaches/trap. Blattella germanica (65.79%) and Periplaneta fuliginosa (34.21%) were captured, with a statistical difference in the constituent ratio in various types of places (χ2=126.509, P < 0.001). The cafeterias of enterprises and public institutions had the highest cockroach infestation rate and density, which were 29.03% and 1.32 cockroaches/trap, respectively. The pathogen detection rate of the cockroach samples was 28.13%. A total of 53 groups of 7 categories of pathogens were detected, including Sapovirus, Norovirus, Astrovirus, Shiga toxin-producing Escherichia coli (STEC), Aeromonas hydrophila, Blastocystis hominis, and Cryptosporidium. The dominant pathogens carried by B. germanica were Sapovirus, B. hominis, and STEC, and those carried by P. fuliginosa were Sapovirus, STEC, and A. hydrophila. Conclusion: Cockroaches in catering places in Pudong New Area carried various human intestinal pathogens, so attention should be paid to targeted cockroach control strategies in catering places.

2023, 34 (4): 467-471.   doi: 10.11853/j.issn.1003.8280.2023.04.005
An analysis of mosquito population density and seasonal fluctuation monitoring results in Hangzhou, Zhejiang province, China, 2017-2021
JIN Bin-bin, WEI Ling-ya, CAO Yang, SHAO Han-wen, WANG Ying-hong, KONG Qing-xin
Abstract136)      PDF (1158KB)(845)      
Objective To investigate the density and seasonal fluctuations of vector mosquitoes in Hangzhou, Zhejiang province, China from 2017 to 2021, and to provide a scientific basis for vector control and mosquito-borne disease prevention. Methods The light trap method was used to investigate 15 districts/counties/cities in Hangzhou from April to November, 2017-2021, in accordance with the "National Vector Surveillance Program" and "Zhejiang Province Vector Surveillance Program". Excel 2016 software was used to summarize the monitoring data, and SPSS 21.0 software was used for statistical analysis. The Chi-square test was used for the difference of mosquito composition ratio in different years, and one-way ANOVA was used for the difference of mosquito density in different habitats. Results From 2017 to 2021, the mosquito density in Hangzhou was 1.99 mosquitoes/light·night, and Culex pipiens pallens/quinquefasciatus (71.90%) was the dominant species. The seasonal fluctuation trend of mosquito density generally showed a bimodal curve, peaking in July and October. There were statistical differences in densities of Cx. pipiens pallens/quinquefasciatus, Cx. tritaeniorhynchus, Aedes albopictus, Anopheles sinensis, and Armigeres subalbatus between different years (all P<0.001). In terms of various habitats, livestock barns/farms had the highest mean mosquito density (4.92 mosquitoes/light·night), and hospitals had the lowest (1.35 mosquitoes/light·night). There were statistical differences in densities of An. sinensis and Ar. subalbatus between various habitats ( F=3.581, P=0.023; F=5.431, P=0.004). Cx. pipiens pallens/ quinquefasciatus was the dominant mosquito species in various habitats, followed by Cx. tritaeniorhynchus, Ar. subalbatus, Ae. albopictus, and An. sinensis. Livestock barns/farms had the highest mosquito densities in terms of any of the above five species. Conclusions The mosquito density in Hangzhou is generally at a low level. Cx. pipiens pallens/ quinquefasciatus is the dominant species. In future mosquito control, livestock barns/farms should be highlighted for special attention. Local districts/cities/counties should take targeted mosquito control measures based on their density changes, distribution, and seasonal fluctuations.
2023, 34 (3): 351-355.   doi: 10.11853/j.issn.1003.8280.2023.03.012
A new species of the genus Heizmannia from Cangyuan of Yunnan, China
Xue-shu DONG, Lin-bo WU, Xiao-lian GUO, Guan-zhen FAN, Hong-ning ZHOU
Abstract135)   HTML    PDF (6834KB)(573)      

This paper describes a new species collected from Cangyuan Wa Autonomus County, Yunnan Province, China, in July 2020: Heizmannia (Heizmannia) cangyuanensis sp. nov.. The main distinguishing features of the new species are as follows: white scales on the ventral side of the basal proboscis; anterior pronotums with all white scales; ventral plates Ⅲ-Ⅵ are all white; the middle lobe of the ventral plate of segment Ⅸ has no scales, with numerous and large the ventral middle teeth in the aedeagus, as well as a finger-like protrusion on the lateral apex of gonostylus. There was no significant difference between the morphology of its larvae and that of Hz. menglianensis larvae. All specimens were preserved in the Mosquito Collection of Yunnan Institute of Parasitic Diseases.

2023, 34 (4): 548-551.   doi: 10.11853/j.issn.1003.8280.2023.04.019
Detection of mutations in the voltage-gated sodium channel genes of field Aedes albopictus populations in Neijiang, Sichuan province, China
TAN Ai, LIU Juan, WANG Ya-wei, ZENG Jia-rui, LIU Peng
Abstract129)      PDF (1053KB)(737)      
Objective To investigate the current resistance status of Aedes albopictus to pyrethroid insecticides at the molecular level through the voltage-gated sodium channel (VGSC) genes testing in three field populations of Ae. albopictus in Neijiang, Sichuan province, China. Methods From June to July in 2021, adult mosquitoes were collected by light trapping method in the Ae. albopictus breeding sites of three counties/cities/districts in Neijiang. For mosquitoes identified as Ae. albopictus, the genomic DNA was extracted to amplify VGSC gene fragment using PCR, followed by detection of mutation types and distribution frequencies at VGSC gene resistance-related loci (loci 1016, 1532, and 1534). Results A total of 107 Ae. albopictus mosquitoes were collected and sequenced successfully. Twenty-eight (26.17%) mosquitoes were detected with the 1016G mutation, six (5.61%) with the 1532T mutation, and 100 (93.46%) with the 1534C/S mutations. The combination analysis of the three loci revealed that 76 (73.08%) mosquitoes had mutations at only one locus, and 25 (24.04%) at two loci. There were two (1.92%) mosquitoes with the wild type at 1016 and mutations at both 1532 and 1534, 22 (21.15%) with the wild type at 1532 and mutations at both 1016 and 1534, and one (0.96%) with the wild type at 1534 and mutations at both 1532 and 1016. None had simultaneous mutations at all the three loci. Conclusions The three field Ae. albopictus populations in Neijiang had frequent pyrethroid target-site mutations, with a high frequency of resistance at locus 1534, where 1534S was the dominant resistance allele, suggesting that the use of pyrethroids should be reduced in chemical control to delay resistance and improve mosquito control.
2023, 34 (3): 314-318.   doi: 10.11853/j.issn.1003.8280.2023.03.006
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