20 February 2023, Volume 34 Issue 1
    

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    Expert Forum
  • National Vector Surveillance System, Chinese Center for Disease Control and Prevention
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 1-8. https://doi.org/10.11853/j.issn.1003.8280.2023.01.001
    Abstract ( 892 ) Download PDF ( 3470 )   Knowledge map   Save
    In 2021, the national surveillance of rodent-borne pathogens of disease vectors had been started up, and a total of 123 prefectures were selected as national surveillance sites. Sampling was completed at 95 surveillance sites. A total of 17 910 rodent specimens were collected, and 16 891 of them were tested. The completion rate of pathogen detection was 94.31%. The overall infection rate of eight monitored rodent-borne pathogens around China was 2.43% (407/16 716) for Hantavirus, 0.02% (4/16 154) for Dabie bandavirus (i.e., severe fever with thrombocytopenia syndrome virus), 5.75% (624/10 850) for Leptospira interrogans, 0.11% (5/4 470) for Rickettsia mooseri, 0.05% (5/10 790) for Orientia tsutsugamushi, 2.39% (75/3 136) for Bartonella, and 0.04% (2/5 075) for Anaplasma phagocytophilum. Francisella tularensis was not detected. More than ten species of rodents were found to be infected with different pathogens in 18 provinces across China. The infection rates of pathogens in rodents in southern regions were relatively high, and the positive rates of pathogens carried by various rodents differed. Rattus norvegicus and Apodemus agrarius were the species in which the most pathogens were detected.
  • Experimental Study
  • Peng ZHANG, Yong-yun ZHOU, Dong-yue LYU, Zhao-kai HE, Ran DUAN, Shuai QIN, De-ming TANG, Meng XIAO, Huai-qi JING, Xin WANG
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 9-13. https://doi.org/10.11853/j.issn.1003.8280.2023.01.002
    Abstract ( 333 ) Download PDF ( 1464 )   Knowledge map   Save
    Objective To investigate the weight of spleen and the histopathological changes of main organs caused by natural infection of Yersinia pestis in Marmota himalayana (marmot), and to reveal the pathogenic characteristics of plague. Methods The ratio of spleen weight to body weight of living marmots and self-dead marmots obtained from 2020 to 2021 was analyzed. The liver, lung, and spleen of normal marmots and self-dead marmots infected with Y. pestis were collected to make pathological sections for observing histopathological changes. Results The ratio of spleen weight to body weight of self-dead marmots infected with Y. pestis was statistically greater than that of marmots not infected with Y. pestis (χ2=33.144, P<0.001). In the liver, lung, and spleen of self-dead marmots infected with Y. pestis, there were cell morphology destruction, inflammatory cell infiltration, vasodilation, and other inflammatory lesions, and vascular injury of the spleen and changes in the red pulp and white pulp were more significant. Conclusion Y. pestis can cause serious inflammatory reaction in marmots, and the pathological changes of the spleen are of more significance for study of the pathogenic process and mechanism of Y. pestis.
  • Qiu-guo LIANG, Xi YANG, Jin-zhi CHENG, Jia-hong WU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 14-20. https://doi.org/10.11853/j.issn.1003.8280.2023.01.003
    Abstract ( 198 ) Download PDF ( 1136 )   Knowledge map   Save
    Objective To determine the polymorphism of mitochondrial cytochrome c oxidase subunitⅠ(mtDNA-COⅠ) gene sequence in different geographical strains of Anopheles sinensis population in Guizhou province, China, and to explore the genetic diversity, genetic differentiation, population expansion, and the correlation between genetic distance and geographical distance. Methods From July 2017 to August 2018, adult mosquitoes around the rice fields at 12 sampling sites in the East, West, South, North, and central area of Guizhou province were captured by light trapping method. The DNA sample of a single mosquito was extracted by kit method after the mosquito was confirmed as An. sinensis by morphology, and the mtDNA-COⅠ gene was amplified and sequenced. The sequencing results were spliced by DNAStar 5.0 software, and the molecular identification of mosquito species was carried out by BLAST comparison in National Center for Biotechnology Information. The haplotype diversity and nucleotide diversity of the mtDNA-COⅠ gene sequence of An. sinensis were analyzed by DnaSP 5.1 software, and the differentiation coefficient (Fst) and gene flow size (Nm) among various populations were calculated. The neutrality test was carried out to clarify the differentiation degree and population expansion among various populations. The genetic distance among various populations and within populations was calculated by MEGA 7.1 software to determine the degree of genetic variation among populations. The geographical distance between populations was calculated according to the latitude and longitude of sampling sites, and the correlation with the corresponding genetic distance was analyzed by the correlation test. Results In this study, 551 sequences of mtDNA-COⅠgene were obtained from 12 geographical strains of An. sinensis in Guizhou province, through molecular biological identification, with a length of 709 bp. Among them, the average content of base A+T was 68.57%, and the average content of G+C was 31.43%. Among the 709 base sites, there were 586 conserved sites, 123 variable sites, 189 monomorphic sites, 278 parsimony-informative sites, and no insertion or deletion sites. A total of 329 haplotypes were detected from 551 sequences, with a haplotype diversity index of 0.992 and a nucleotide diversity of more than 0.015 22. The Fstvalue of 12 populations was between 0.000 8 and 0.420 7, and the Nm values ranged from 0.086 1 to 75.239 2. The neutrality test statistic values were all negative values. The genetic distance within populations ranged from 0.007 1 to 0.052 9, and the genetic distance between populations ranged from 0.007 9 to 0.052 2. The genetic distances within Zhijin and Duyun populations were larger than those within other populations. There was no correlation between genetic distance and geographical distance. There might be a certain geographical isolation between different populations, but the genetic distance between populations was not related to the geographical distance. Conclusion There is abundant genetic diversity among different geographical strains of An. sinensis populations in Guizhou province, in which regional population expansion has been experienced in history. There may be some degree of genetic differentiation and geographical isolation, but there is also gene exchange among populations in a certain range, showing a distribution pattern of coexistence of exchange and isolation.
  • Li YANG, Nan WANG, Fei-xiang TENG, Gui-fang MA, Jin-xia SUN
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 21-25. https://doi.org/10.11853/j.issn.1003.8280.2023.01.004
    Abstract ( 167 ) Download PDF ( 1017 )   Knowledge map   Save
    Objective To prepare the recombinant protein of the group 33 allergen of Dermatophagoides pteronyssinus (Der p 33), and to determine its serum IgE-binding rate. Methods The primers were designed according to the published sequence of Der p 33 (GenBank No. AUX14773), and the Der p 33 gene of D. pteronyssinus was amplified by RT-PCR. After being identified by agarose gel electrophoresis, the amplification product was connected to the pET-28a (+) vector and heat-transformed into Escherichia coli, and the positive recombinant plasmid was selected for sequencing. The pET-28a (+)-Der p 33 plasmid was transformed into E. coli Rosetta 2 (DE3) plysS, expressed with the induction by isopropyl-β-D-thiogalactoside (IPTG), and purified by column chromatography and was then subjected to Western blotting analysis. The structure and physicochemical properties of Der p 33 were predicted by bioinformatics software. Results The encoding gene of Der p 33 was obtained, which had a full length of 1 383 bp and a relative molecular weight of 51 432.81 and encoded 460 amino acids. The secondary structure was predicted to contain α-helix (40.87%), β-turn (7.17%), extended strand (17.39%), and random coil (34.57%). The purity of recombinant protein was >95.00%. According to the Western blotting analysis, the serum IgE-binding rate of recombinant Der p 33 was 18.75% (3/16). Conclusion The Der p 33 gene was successfully cloned, and the purified recombinant protein had serum IgE-binding activity, which lays a foundation for the development of diagnostic reagents for the allergen component of D. pteronyssinus and the bioproducts of desensitization treatment.
  • Yu-yan WU, Qin-mei LIU, Jin-na WANG, Tian-qi LI, Ming-yu LUO, Zhen-yu GONG
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 26-30. https://doi.org/10.11853/j.issn.1003.8280.2023.01.005
    Abstract ( 260 ) Download PDF ( )   Knowledge map   Save
    Objective To investigate the resistance of Musca domestica populations to commonly used insecticides in different regions of Zhejiang province, China, in 2021, and to provide a scientific basis for rational insecticide use of fly control. Methods Different field populations of M. domestica were collected from 12 monitoring sites in Hangzhou, Ningbo, Wenzhou, Shaoxing, Huzhou, Jiaxing, Jinhua, Quzhou, Taizhou, Lishui, Zhoushan, and Yiwu, Zhejiang province from April to November 2021. The topical application method was used to determine the resistance of M. domestica to seven commonly used insecticides of pyrethroids, organophosphorus and carbamates. Results The resistance ratios of M. domestica populations to beta-cypermethrin, deltamethrin, permethrin, beta-cyfluthrin, dichlorvos, chlorpyrifos, and propoxur were 0.83-255.00, 4.44-158.78, 6.11-64.81, 1.76-53.57, 2.45-130.11, 3.37-10.39, and 2.52-1 149.63 in 11 prefecture-level cities and Yiwu, Zhejiang province. Conclusion Some field populations of M. domestica in different regions of Zhejiang province have developed varying degrees of resistance to many of the seven commonly used insecticides. In the future fly control, measures should be taken to standardize the use of chemical insecticides based on the results of resistance monitoring in order to effectively reduce the density of flies and delay the development of resistance.
  • Vector Surveillance
  • Biao DUAN, Si-xiang ZHANG, Cai-feng ZHAO, Mei HONG, Li-qiong SU, Wen-hong ZHAO, Zhi-ming YANG, Liang LU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 31-38. https://doi.org/10.11853/j.issn.1003.8280.2023.01.006
    Abstract ( 282 ) Download PDF ( )   Knowledge map   Save
    Objective To analyze the species composition and interannual and seasonal fluctuations of main host animals and flea vectors at historical and new plague foci in Jianchuan county, Yunnan province, China, and to explore the relationship between the population characteristics of hosts and vectors and plague epidemics. Methods Plague surveillance data were collected from Shaxi town surveillance point (historical) and Jinhua town surveillance point (new) in Jianchuan county, Yunnan province from 2012 to 2021. Descriptive and correlation methods were used to analyze the population characteristics of major host animals and fleas. Results The host animals found at Shaxi town surveillance point involved 22 species, 19 genera, 7 families, and 6 orders (outdoors:20 species, 18 genera, 7 families, and 6 orders; indoors:5 species, 4 genera, 2 orders, and 2 families). The host animals found at Jinhua town surveillance point involved 21 species, 17 genera, 6 families, and 5 orders (outdoors:20 species, 17 genera, 6 families, and 5 orders; indoors:10 species, 8 genera, 5 families, and 3 orders). The dominant species were Eothenomys miletus and Apodemus chevrieri at both monitoring sites, accounting for 37.73% and 45.90% in Shaxi town and 35.86% and 51.43% in Jinhua town, respectively. The fleas collected at the two surveillance sites involved 8 species, 8 genera, and 3 families (rodent body fleas:8 species, 8 genera, and 3 families; nest fleas:4 species, 4 genera, and 2 families). In Shaxi town, the body flea infestation rate was 28.91% (3 693/12 772), and the total flea index was 0.79 (10 144/12 772). In Jinhua town, the body flea infestation rate was 29.39% (959/3 263), and the total flea index was 0.71 (2 321/3 263). Frontopsylla spadix and Neopsylla specialis were the dominant species at both monitoring sites, accounting for 33.20% and 16.30% in Shaxi town and 36.49% and 19.09% in Jinhua town, respectively. Conclusion By comparing the population characteristics of main host animals and flea vectors at historical and new plague foci in Jianchuan county, it is indicated that the population characteristics of A. chevrieri and ectoparasitic F. spadix and N. specialis are more closely related to plague epidemics.
  • Jia-yong ZHANG, Chun-yu WANG, Yu-yin BAI, Zhi LI, Ji-bo ZHANG, Jun DING
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 39-43. https://doi.org/10.11853/j.issn.1003.8280.2023.01.007
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    Objective To investigate the density, species composition, and seasonal fluctuation of rodents in Liaoning province, China from 2018 to 2020, and to provide a scientific basis for formulating rodent control strategies. Methods Surveillance points were set in residential regions and special industries for urban areas, and in natural villages for rural areas. Rodent density was monitored using the night trapping method. With SPSS 23.0 and Excel 2013 softwares, descriptive methods were used to analyze the species composition and seasonal variation of rodents in the urban and rural areas of Liaoning province. Results From 2018 to 2020, a total of 207 738 effective rodent traps were set in Liaoning province. A total of 2 237 rodents were captured, with an average rodent density of 1.08%. The rodent density in rural areas (1.53%) was statistically higher than that in urban areas (0.63%). The urban rodent density and overall rodent density in 2018 and 2019 showed a unimodal curve, all peaking in July. The rural rodent density and overall rodent density in 2020 showed a bimodal curve. Rattus norvegicus was the dominant rodent species in Liaoning province. Conclusion Rodent density showed a slight downward trend in Liaoning province from 2018 to 2020, with a unimodal pattern in 2018 and 2019 and a bimodal pattern in 2020. There was a relatively high rodent density in rural habitats, where rodent control should be strengthened. Based on the seasonal fluctuation of rodents, comprehensive rodent control measures should be taken before the peak period, to reduce the density of rodents and thereby prevent rodent-borne diseases.
  • Ya-jie HU, Zhen-chuan ZHANG, Ling-ling LI, Ji-gang YU, Guan-cui LI
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 44-47. https://doi.org/10.11853/j.issn.1003.8280.2023.01.008
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    Objective To investigate the bionomic characteristics of mosquito populations in Sichuan province, China from 2017 to 2021, and to provide a scientific basis for mosquito control and risk assessment of mosquito-borne diseases. Methods Adult mosquito surveillance data in 21 cities/prefectures of Sichuan province from 2017 to 2021 software were collected. Mosquito surveillance was conducted continuously using the light trap method. Excel 2007 and SPSS 25.0 softwares were used for statistical analysis. Results From 2017 to 2021, the mean mosquito density was 1.60 mosquitoes/lamp·hour at 21 surveillance sites in Sichuan province. The mosquito density generally fluctuated at similar levels in the five years. The dominant mosquito species were Culex pipiens quinquefasciatus, Cx. tritaeniorhynchus, and Anopheles sinensis, accounting for 35.64%, 33.98%, and 10.78% of the total catches, respectively. Among all habitats, the overall mosquito density was highest in livestock sheds (4.51 mosquitoes/lamp·hour) and lowest in hospitals (0.39 mosquitoes/lamp·hour). The overall mosquito density in rural areas was statistically higher than that in urban areas (Z=-6.523, P<0.001). The seasonal variation curve of mosquito density in Sichuan province showed a single peak, which occurred during June to July. Conclusion The mosquito densities were relatively low at surveillance sites in Sichuan province except for 2019. The dominant mosquito species were Cx. pipiens quinquefasciatus, Cx. tritaeniorhynchus,and An. sinensis. The rural areas had the highest mosquito density, which should be the key area for mosquito control. May to September was the peak period of dominant mosquito activities, and comprehensive mosquito control should be strengthened during this period.
  • Hui GUO, Jing LIU, Wei-ping MAO, Hao DING, Qian-qian WU, Liang-cai ZHOU, Li-qun WU, Xiao-min CHEN
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 48-52. https://doi.org/10.11853/j.issn.1003.8280.2023.01.009
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    Objective To analyze the ecological monitoring data of Aedes vector in Wuhan, China, 2018-2021, and to provide a scientific basis for effective prevention and control of dengue fever. Methods The Breteau index (BI) and double layered mosquito net methods were used for ecological monitoring of Aedes larvae and adults, respectively. All data were collected by Excel 2010 and statistically analyzed by SPSS 20.0 software. Differences in BI at different time points were analyzed by Chi-square test, and differences in net trap index between different habitats at different time points by analysis of variance or Kruskal-Wallis test; the risk of dengue fever transmission was assessed. Results In 2018-2021, the mean BI was 4.50, and the net trap index was 2.44 mosquitoes/net·h. The density index of Aedes fell to the lowest level in 2019 and showed an upward trend in 2020-2021. Meanwhile, the net trap index in residential areas was higher than that in waste tire stacking sites (H=29.468, P<0.001). The seasonal fluctuation was not completely consistent in different years; the peak BI value was observed from June to August, and the peak net trap index was observed in July and August. In 2018-2021, 64.52% (20/31) of the monitored months presented a risk of dengue fever transmission, and the BI value reached the risk threshold of dengue fever outbreak in July and August in 2021. Conclusion The fluctuation trend of vector Aedes mosquito density is on the rise in Wuhan, and the risk of dengue fever transmission has increased. Aedes vector control measures should be strengthened and improved.
  • Zhuang-fei WANG, Xue LU, Xiao-hui HOU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 53-57. https://doi.org/10.11853/j.issn.1003.8280.2023.01.010
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    Objective To investigate the species distribution and species composition of Culicoides in Huzhu, Menyuan, Qilian, and Zeku county in Qilian Mountain National Park and Maixiu Nature Reserve in Qinghai province, China, and to discuss the influence of meteorological factors on the distribution of Culicoides in the above areas. Methods From July to August 2020, Culicoides midges were captured with light traps in the above four counties. After classification and identification, the Pearson correlation test and plotting of relationship between altitude, meteorological factors, and the number of collected Culicoides were performed using SPSS 25.0 and GraphPad Prism 8.2.1 softwares. Results A total of 8 417 Culicoides midges were collected, and 10 species from 5 subgenera were identified, including 6 newly recorded species in Qinghai province, namely C. grisescens, C. punctatus, C. segnis, C. nigritus, C. halonostictus, and C. pallidicornis. The dominant species in all four counties was C. grisescens, which accounted for 33.60%, 85.85%, 97.95%, and 97.97% of the total number of Culicoides midges at the four sampling sites, respectively. The blood sucking rates of C. grisescens, C. pallidicornis, and C. pulicaris were 2.23%, 1.23%, and 1.89% in Zeku county, respectively. The Pearson correlation test showed that the single-day number of captures of Culicoides had no correlation with altitude (R2=0.130, P=0.639) and wind speed (R2=0.059, P=0.641), but showed negative correlation with rainfall (R2=0.199, P=0.038) and average temperature (R2=0.838, P=0.010) in the survey area. Conclusion There are 10 species of Culicoides from 5 subgenera captured in the four counties of eastern Qinghai province. C. grisescens is the dominant species. The population density of Culicoides in this area is correlated with the rainfall and average temperature.
  • Vector-borne Disease
  • Nan CHANG, Ruo-bing ZHOU, De-long MA, Lu ZHANG, Xiao-hui WEI, Jun WANG, Qi-yong LIU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 58-64. https://doi.org/10.11853/j.issn.1003.8280.2023.01.011
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    Objective To analyze the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS) in China from 2006 to 2021, to investigate the influence of non-pharmaceutical intervention against coronavirus disease 2019 (COVID-19) on HFRS prevalence, and to provide a scientific basis for the subsequent formulation of relevant policies. Methods Descriptive epidemiological methods were utilized to statistically analyze the epidemiological characteristics of HFRS in China from 2006 to 2021. The data of HFRS cases from 2006 to 2019 were used to establish an autoregressive integrated moving average (ARIMA) model to predict the number of HFRS cases in 2020-2021, and the predicted values were compared with the actual observed values. Results The number of HFRS cases in China was relatively stable in 2006-2021, and the number of deaths were significantly reduced. HFRS had obvious seasonality, with two peaks of incidence in a year, i.e., May-June and November. The number of cases in northeast China decreased, but the affected areas in the whole country expanded, and some areas were still at risk of outbreak. The number of male cases was significantly higher than that of female cases. The peak age group of onset was 35-49 years for males and 45-59 years for females, and there was a significant difference in the age composition between males and females (χ2=2 802.807, P<0.001). Farmers were the main affected population, accounting for more than half of the total cases. The seasonal ARIMA model was established by fitting the data of HFRS cases from 2006 to 2019 with R 4.0.4 software, which was (2,0,2)(1,1,0)12 and was well fitted. The actual observed value of HFRS cases in 2020-2021 was close to the predicted value, within its 95% confidence interval. Conclusion HFRS is an important public health problem in China and the overall trend of its prevalence is relatively stable. It is necessary to strengthen the surveillance and implement more accurate prevention and control measures. The measures for COVID-19 prevention and control in China have no significant impact on the prevalence of HFRS during 2020-2021.
  • Jing WANG, Fei LUO, Wei-tao HE, Li-na JIANG, Chao ZHANG, Mei LIN, Jun ZENG
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 65-69. https://doi.org/10.11853/j.issn.1003.8280.2023.01.012
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    Objective To investigate the epidemiological characteristics of person, time, and place of dengue fever and their domestic and abroad sources in Guangxi Zhuang Autonomous Region (Guangxi), China from 2016 to 2020, and to provide a scientific basis for the prevention and control of dengue fever in the future. Methods The data on dengue fever in Guangxi from 2016 to 2020 were collected from the notifiable disease reporting system. With Excel 2010 and SPSS 20.0, descriptive epidemiological methods were used to analyze the epidemiological characteristics of imported and local cases of dengue fever in Guangxi in the past five years, and to analyze the source of infection and the epidemic pattern of dengue fever in Guangxi. Results A total of 2 183 dengue cases were reported in Guangxi from 2016 to 2020, with an average incidence of 0.89/100 000. Dengue fever was sporadic during 2016 to 2018, and occurred in outbreaks in 2019 and 2020. The incidence of dengue fever peaked in 2019, accounting for 80.20% of the total reported cases. The male-to-female ratio of imported cases was statistically higher than that of local cases (χ2=5.262, P=0.022).The majority of local cases were between 30 and 39 years old (22.61%) and the majority of imported cases were between 30 and 39 years old (27.94%). The local and imported cases showed similar trends in epidemic seasons, mainly in summer and autumn. The imported cases were mainly from Guangdong province in China (74 cases, 88.10%) and from Cambodia (83 cases, 65.35%). In terms of occupational distribution, domestic and overseas imported cases were mainly household workers and unemployed workers, accounting for 20.78% and 20.47% respectively, while domestic imported cases were mainly farmers (43.03%). Conclusion Dengue fever in Guangxi has an increased trend from sporadic patterns to outbreaks. It is important to strengthen the education on dengue control for key populations during epidemic seasons, to enhance the sensitivity of quarantine at entry and exit ports and the level of diagnosis in medical institutions, and to promptly identify and report cases, which are important for reducing the occurrence and spread of dengue fever.
  • WU Hong-pan, LIU Dong-zhi, CHU Wen-wen, GULINA Zainula, QI Ying-jie, CHU Hong-jun
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 70-76. https://doi.org/10.11853/j.issn.1003.8280.2023.01.013
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    Objective To study the relationship between microhabitats of Rhombomys opimus nest area and environmental factors in the desert area of the Mount Kalamaili Ungulate Nature Reserve, China, and investigate the factors affecting the selection of the nest domain of R. opimus, and to provide a basis for rodent control. Methods In the spring and summer of 2019 and spring, summer, and autumn of 2020, we investigated habitat factors (including elevation, slope, the number of plant species, vegetation coverage, and biomass) in 111 R. opimus home range quadrats and 111 control quadrats (without R. opimus). A quadrat was 5 m×5 m in size. Results Three ecological factors significantly affected the selection of microhabitats of R. opimus nest area:elevation, soil moisture content, and plant species number (all P<0.05). Principal component analysis showed that the main factors affecting the selection of microhabitats of R. opimus nest area were vegetation coverage (0.863), distance from roads (0.761), distance from residential areas (0.734), and shrub coverage (0.719). Conclusion The home range of great gerbils tends to have high elevation, low soil moisture content, diverse plant species, flat beach (including sandy and alkaline soil substrates), high vegetation coverage, and high shrub coverage, and be far away from human settlements and roads. The results can provide an important theoretical basis for the scientific control of great gerbils.
  • Technology and Method
  • Rong WANG, Min MA, Zhong-fa WANG, Ji-luo LIU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 77-81. https://doi.org/10.11853/j.issn.1003.8280.2023.01.014
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    Objective To compare and evaluate the detection effect between an improved polymerase chain reaction (PCR) method and three current standard methods for pathogenic Leptospira, and to provide an improved method in early diagnosis of patients and host animal monitoring. Methods A step of reverse transcription process was added to the recommended pathogenic Leptospira detection method (method 3) in National Vector Etiology Surveillance Program (Trial), without changing the primers and probes, to form an improved method (method 4). Four PCR methods, i.e., Method 4, the recommended method of Industry Standards for Health Care (method 1), the recommended method of Industry Standards for Inspection and Quarantine (method 2), and method 3, were used to detect Leptospira positive samples with series dilutions, early serum samples of patients, and rodent kidney specimens in parallel, and to evaluate the detection effect. Results The sensitivity of method 4 was 10 000 times that of methods 1 and 2, and 1 000 times that of method 3. Leptospira nucleic acids in early serum of patients were only detected by method 4. The detection rates of Leptospira in 100 rodent kidney specimens were 2.00%, 4.00%, 8.00%, and 40.00% by the four methods, respectively. There was a significant difference in the positive detection rate between method 4 and methods 1, 2, and 3 (all P<0.001) and no significant difference between methods 1, 2, and 3 (P>0.05). Conclusion The improved method has a superior detection effect to the other three current standard methods in the early diagnosis of patients with leptospirosis and the rodent kidney.
  • Investigation
  • Lu ZHANG, Xiao-hui WEI, Nan CHANG, Hong-yun LI, Xiao-yan SI, Xue-feng BAI, Jun WANG, Qi-yong LIU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 82-90. https://doi.org/10.11853/j.issn.1003.8280.2023.01.015
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    Objective To investigate the species composition of rodents and ectoparasitic fleas on rodents as well as the spatiotemporal distribution and changes of the flea index of dominant rodents in Xilin Gol League,Inner Mongolia Autonomous Region,China,and to provide a basis for plague risk assessment and its prevention and control decisions-making. Methods With the monitoring data of 12 plague surveillance points in Xilin Gol League from 2012 to 2021,we used descriptive epidemiological methods to analyze the temporal and spatial distribution characteristics of main rodents and their flea indexes. Results From 2012 to 2021,a total of 50 551 rodents were captured in Xilin Gol League,involving 18 species,13 genera,and 4 families. Among them,19 958 rodents carried fleas,with an average flea infestation rate of 39.48%. A total of 83 147 fleas were collected,belonging to 35 species/subspecies,14 genera,and 5 families,with an overall flea index of 1.64. Meriones unguiculatus,Spermophilus dauricus,and Lasiopodomys brandtii were the dominant rodent species. Citellophilus tesquorum mongolicus, Xenopsylla conformis conformis,Frontopsylla luculenta,and Nosopsyllus laeviceps kuzenkovi were the main parasitic fleas. M. unguiculatus carried more diverse flea species on the body surface than L. brandtii and S. dauricus. The mixed flea index (S=-25.000, P=0.032) and S. dauricus flea index (S=-23.000, P=0.049)showed a downward trend in Xilin Gol League during the ten years. The M. unguiculatus flea index and L. brandtii flea index had no significant changes. The S. dauricus flea index was significantly higher than the L. brandtii flea index (H=15.000, P<0.001)and the M. unguiculatus flea index (H=-15.000, P<0.001). There was no significant difference between the L. brandtii and M. unguiculatus flea indexes (H<0.001, P=1.000). The mixed flea index peaked in July at 4.47. The M. unguiculatus flea index was significantly different between banners/counties of Xilin Gol League (H=52.579, P<0.001), which was highest in Sonid Left and Xianghuang banners. The S. dauricus flea index was significantly different between banners/counties of Xilin Gol League (H=73.253, P<0.001),which was highest in West Ujimqin and Zhengxiangbai banners. The L. brandtii flea index showed no significant difference between banners/counties of Xilin Gol League (H=5.864, P=0.118). Conclusion The three types of plague foci in Xilin Gol League overlap. Meriones unguiculatus carries a diversity of fleas,with a high risk of transmitting plague bacteria. Surveillance points should comprehensively monitor plague epizootics to prevent plague from resurging among animals and expanding to human beings.
  • Yan-fen NIU, Song ZHOU, Guang LIU, Xiao-wei LIU, Yi-hui ZHANG, Hai-feng WANG, Ran DUAN, Xin WANG, Xiao-yan YANG, Yue-cong DU, Xi WANG, Sheng ZHAO, Chun-xia JIN, Guo-yi DU, Xian-ming SHI, Yao-ren CUI, Ping YAN
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 91-93. https://doi.org/10.11853/j.issn.1003.8280.2023.01.016
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    Objective To investigate the distribution of Yersinia pseudotuberculosis and Y. enterocolitica in the natural focus of plague in Hebei province, China, and to provide a scientific basis for rodent borne diseases prevention and control. Methods Samples from the lingual root and ileocecum of host animals were collected, and culture and polymerase chain reaction (PCR) were used to detect Y. enterocolitica and Y. pseudotuberculosis. Results A total of 1 048 samples were collected, including 543 samples from the lingual root and 505 samples from the ileocecum. All bacterial cultures were negative for pathogenic Yersinia. All samples were negative for Y. pseudotuberculosis with PCR screening. Two foxA+ (ferrioxamine receptor gene) samples for Y. enterocolitica were screened out by PCR, and the annual positive rate was 0.41% (2/490). Conclusion The main host in some natural foci of plague in Hebei province carries Y. enterocolitica, and the surveillance of other pathogenic Yersinia should be strengthened at the same time of plague surveillance.
  • Ren-dong YANG, Yuan-sheng FANG, Rong-na ZHANG, Zuo-ru LIANG, Xiao-peng QI
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 94-100. https://doi.org/10.11853/j.issn.1003.8280.2023.01.017
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    Objective To investigate the technical capabilities of malaria control institutions in China, and to provide a reference for malaria control in the post-eradication era as well as foreign medical aid. Methods Two self-made questionnaires were used to investigate the technical capabilities (malaria control and mosquito vector surveillance) of provincial centers for disease control and prevention and institutes of parasitic diseases. The capacity for malaria diagnosis and treatment of medical institutions was analyzed based on the data on malaria cases from the China Information System for Disease Control and Prevention. The relevant official websites were browsed to collect the antimalarial products and enterprises with prequalification certificates from the World Health Organization (WHO) or registration approvals from the National Medical Products Administration. By reviewing the literature to tease out the technical progress in vaccines, drugs, and other fields of malaria. The data of foundations and other institutions were collected by means of expert consultation and interview. Results National vector surveillance sites were set in all 31 provinces, autonomous regions, or municipalities directly under the central government and Xinjiang Production and Construction Corps ("province" below), with 5.35 sites per province. There were 178 staff members, with 5.74 persons per province. Over 26 provinces had mosquito vector laboratories and mosquito breeding rooms, and carried out mosquito density surveillance, mosquito species and ecology research, and insecticide types and resistance research. Forty-seven persons from 30 provinces had WHO certificates of microscopy. Twenty-four malaria endemic provinces had 227 staff members for malaria prevention and control, with 9.45 persons per province. Among them, 63.88% were aged 30 to 49 years, 52.42% had a senior or vice-senior title, and 58.59% had ≥ 10 years of working in malaria. All the 24 provinces had malaria laboratories, and there were 145 malaria laboratories in total (6.04 laboratories per province), all with the abilities of plasmodium blood smear microscopy and nucleic acid detection. Sixteen provinces had approvals of foreign aid projects or provincial/ministerial/above level research projects, with 56 projects in total, covering Asia, Africa, and Oceania. WHO-prequalified enterprises included 26 manufacturers of active pharmaceutical ingredients, three manufacturers of long-lasting insecticidal nets, one medicine manufacturer, and one insecticide manufacturer. Forty-eight companies of antimalarial drugs had registration approvals from the National Medical Products Administration. At least 77.30% of medical institutions had certain capacities for the diagnosis and treatment of falciparum malaria. Artemisinin and its derivatives developed by the China Academy of Chinese Medical Sciences were the only WHO-recognized specific antimalarial drugs. Pfcp-2.9 antigen developed by universities was approved for clinical trials. Two vaccines were put into preclinical studies. At least 31 customs ports were capable to monitor Anopheles mosquitoes, and four customs ports had malaria rapid diagnostic test abilities accredited by the College of American Pathologists. The WHO, Global Fund, Bill & Melinda Gates Foundation, Health Poverty Action, Chinese Preventive Medicine Association, and China Chamber of Commerce for Import & Export of Medicines & Health Products played important roles in malaria elimination in China by providing funds, organizing technical training, participating in malaria elimination assessment, and helping enterprises apply for WHO prequalification. Conclusion China has established multiple work networks nationwide, built joint prevention and control mechanisms involving multiple departments, and accumulated technical talents with high professional levels in various technical fields, but still with shortcomings in some technical fields.
  • Li-qun WU, Xiao-min CHEN, Ji-yong BAO, Liang-cai ZHOU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 101-104. https://doi.org/10.11853/j.issn.1003.8280.2023.01.018
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    Objective To determine the resistance status of Aedes albopictus to commonly used insecticides in Wuhan, China, 2019-2021, and to provide a basis for formulating scientific and reasonable prevention and control measures. Methods Insecticide susceptibility tube test was used to examine the mortality of Ae. albopictus adultsto six insecticides at the diagnostic dose, and larva dipping test was used to examine the toxicity of nine insecticides to Ae. albopictus larvae. SPSS 20.0 software was used for probability regression analysis to calculate the median lethal concentration or half maximal inhibitory concentration of the insecticide to Ae. albopictus larvae. Results Ae. albopictus adults developed varying degrees of resistance to deltamethrin, permethrin, beta-cypermethrin, and lambda-cyhalothrin, with mortality rates ranging from 5.88% to 68.75%, and showed sensitivity to propoxur and malathion, with mortality rates of 100%. Ae. albopictus larvae demonstrated different degrees of resistance to deltamethrin, beta-cypermethrin, propoxur, Bacillus thuringiensis, and pyriproxyfen, with resistance ratios ranging from 4.40 to 76.20, and showed sensitivity to malathion and temephos, with resistance ratios of 0.30 and 2.38, respectively. Conclusion Ae. albopictus in Wuhan develops varying levels of resistance to different types of insecticides, including pyrethroids, carbamates, biological insecticides, and insect growth regulators. Surveillance and management of resistance of Ae. albopictus should be strengthened to further improve to formulate scientific, reasonable, and comprehensive prevention and control measures.
  • Yin-xu HOU, Zhi-wei LIU, Yan-jie ZHANG, Feng-tao YANG, Wen-jun WANG, Feng-xia MENG, Fa-yuan HUANG
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 105-108. https://doi.org/10.11853/j.issn.1003.8280.2023.01.019
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    Objective To investigate the insecticide resistance level of Musca domestica in human settlements and surroundings in Hefei, China, and to provide a scientific basis for insecticide use and management as well as fly control. Methods The topical application method was used to determine the resistance levels of M. domestica to insecticides. Probit analysis was performed with SPSS 22.0 software to calculate the toxicity regression equation as well as median lethal dose (LD50) and 95% confidence interval. Results For M. domestica in Hefei, 2021, the LD50 values of dichlorvos, permethrin, deltamethrin, alpha-cypermethrin, beta-cypermethrin, and lambda-cyhalothrin were 0.321 55, 0.775 62, 0.956 54, 0.519 00, 0.542 90, and 0.532 90 μg/♀, respectively; the relative resistance coefficients were 28.21, 133.73, 1 471.60, 112.83, 63.13, and 166.53, respectively, indicating high resistance levels of M. domestica to all the six insecticides. Conclusion M. domestica in Hefei developed high resistance to the six commonly used insecticides, which should be avoided or reduced in use. Other insecticides of high sensitivity or with different mechanisms of action should be used in alternation to delay the development of resistance.
  • Jin LIU, Shu-li HUANG, Hong-mei LI, Hasibaolidao, Ya TU, Xiao-min ZHANG, Chao LI, Wen-ji HUANG
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 109-113. https://doi.org/10.11853/j.issn.1003.8280.2023.01.020
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    Objective To study the effects of grassland roads on the density of Microtus gregalis and the rate and degree of Capillaria hepatica infection in M. gregalis. Methods From July to August 2006, in typical grassland (where M. gregalis was the dominant rodent species) in West Ujimqin Banner, Xilin Gol League, Inner Mongolia Autonomous Region, China, the relationship between grassland roads and the rate of C. hepatica infection in M. gregalis was investigated. The grassland was divided into experimental area (close to the grassland road) and control area (500 m away from the road). Each area was equally divided into six plots. Almost all narrow-skulled voles in plots were captured using rodent traps. The infection rate of C. hepatica was divided into four levels (0-3) from mild to severe. The infection rate was recorded and the independent sample t test was used to analyze data. Results The mean C. hepatica infection rate of M. gregalis was statistically higher in the experimental plots than in the control plots[(26.15±4.28)% vs (16.23±3.38)%, t=4.108, P=0.002]. The mean infection level of the infected voles was statistically higher in the experimental plots than in the control plots (1.55 vs 1.15, t=3.908, P=0.003). There was no statistical difference in the mean number of captured narrow-skulled voles between the experimental and control plots (23.17 vs 21.33, t=1.003, P=0.339). Conclusion Grassland roads have no statistical impact on the density of narrow-skulled voles, but narrow-skulled voles living close to grassland roads are more likely to have C. hepatica infection, which tend to be more severe, compared with those away from grassland roads. Grassland roads could promote the spread of C. hepatica, which should be paid attention to.
  • Taxonomic Identification
  • Jin-xin MENG, Jing-lin WANG, Guo-ping LIU
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 114-116. https://doi.org/10.11853/j.issn.1003.8280.2023.01.021
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    Objective To investigate the species distribution of midges in Cona county, Tibet Autonomous Region, China. Methods Midges were captured with light traps in cattle pens and residential areas in Cona county, followed by slide specimen preparation with phenol balsam. Results We described a male midge of Alluaudomyia desma Yu, 2005 found in Cona county. The identifying characteristics are:Eyes with interfacetal hairs. Wing with a dark spot in r-m cross-vein,and with a dark spot in distal portion of R2 cell. Genitalia ninthtergum apically with two angular process, adeagus with two digitate process in distal portion, parameres with rod-shaped, basal portiot with two hookted bend,and end with lateral curvature. The wing pattern of male All. desma is similar to that of All. longzhouensis Hao et Yu, 1991, but the latter male insect has distinct aedeagus and paramere appearances from male All. desma. The specimen is deposited in the Center for Disease Control and Prevention of Northern Theater Command (Shenyang, 110034). Conclusion The characteristics of the newly found male specimen, which are consistent with the original description of the female holotype specimen. Combined with morphological characteristics, collection location and time, it was identified as All. desma, which supplement important male information that was lacking in the original species, and provides a reference for the classification and identification of All. desma.
  • Review
  • Zi-wei LI, Jia-xiang YIN
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 117-121. https://doi.org/10.11853/j.issn.1003.8280.2023.01.022
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    Rodents are not only causing massive damage to human production and life, but they also can pose a great threat to human life and health as they carry pathogens. Controlling the rodent population can reduce rodent infestation and effectively prevent rodent-borne diseases. This review demonstrates the relationship between biological, soil, meteorological, human activities and rodents, and clarifies the influence of environmental factors, human activities on rodents, which provides references for effective control of rodent infestation and scientific prevention and control of rodent-borne disease epidemics.
  • ZHOU Xiao-jie, ZHANG Yong, WU Dan, ZHANG Hong-jiang, GAN Ya-di, TANG Wei-min, TONG Ying
    Chinese Journal of Vector Biology and Control. 2023, 34(1): 122-127. https://doi.org/10.11853/j.issn.1003.8280.2023.01.023
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    In 2022, the Winter Olympic Games was first held in Beijing, China. To ensure that the key areas of the Winter Olympic Games were not affected by vectors and to minimize the risk of vector-borne diseases, the density of vectors in the key areas of the Winter Olympic Games and the cities where they are located should be effectively controlled. This paper focuses on the vector control strategy and working mechanism during Beijing 2022 Winter Olympic Games, and discusses the control model, risk assessment, inter-sectoral coordination, publicity and training, hazard monitoring, control technology, supervision and inspection, and emergency response with Main Media Center as an example. The vector density was effectively controlled during the Winter Olympic Games, no plague and other vector-borne diseases occurred, and there were no incidents of vector-borne hazards. The vector control model, technical measures, and working mechanism formed during the Beijing 2008 Summer Olympic Games were verified and deepened in the Beijing 2022 Winter Olympic Games, which can be used as a guidance for vector control in similar large-scale activities in the future.