Global climate change may have an impact on disease vectors and vector-borne diseases and seriously threaten human health. Based on the current research findings,this article summarizes the impact of climate change on vectors and vector-borne diseases in China,and it is revealed that meteorological factors,including temperature,humidity,and precipitation,have a significant impact on the number,density,and distribution of disease vectors,as well as the spatial and temporal dynamics,epidemic frequency,and intensity of vector-borne diseases,with the coexistence of spatial-temporal heterogeneity. Climate change drives the epidemic areas of vector-borne diseases,such as dengue fever,to expand significantly to the west and the north and significantly increases the epidemic frequency and intensity of such diseases,and with continuous climate warming,there will be accelerately increases in epidemic intensity and risk population in the future. The research on adaptive strategies and measures has been carried out for the new challenges of vector-borne diseases caused by climate change and has provided a solution combining "top-down" administrative intervention and "bottom-up" community-integrated vector management. The WHO Global Vector Control Response 2017-2030 on a basis of sustainable vector management strategy puts forward specific objectives and requirements for the control of vector-borne diseases. Under the guidance of this strategy in the future,China needs to increase funding,pay attention to the cultivation of high-end talents, upgrade the surveillance system for vectors and vector-borne diseases in the context of climate change,and strengthen the research on risk assessment,prediction and early warning,control strategies,and intervention measures,so as to effectively cope with the new challenges of climate-sensitive vector-borne diseases,protect the vulnerable populations and public health security,and provide continuous,innovative,and precise strategies and measures.

Both dengue fever (DF) and chikungunya fever (CHIKF) are important mosquito-borne viral diseases with global distribution, and these two diseases have relatively similar epidemiological and clinical features, with the main vectors of Aedes aegypti and Ae. albopictus. The local epidemic of DF occurred in China-Myanmar and China-Laos border areas of Yunnan province, China every year in 2013-2019, and it also occurred in China-Vietnam border area in 2019, while the local epidemic of CHIKF occurred in China-Myanmar border area for the first time in 2019. The imported cases of DF and CHIKF from Myanmar, Laos, Thailand, and/or Vietnam were the main cause of the local epidemic of these two diseases in Yunnan province. The special geographical location and ecological environment of Yunnan province are suitable for the breeding of the vector Aedes mosquitoes and the transmission of DF and CHIKF viruses. There are still high risks of re-epidemic or pandemic of DF and CHIKF in this region, with the possibility of endemic an severe cases of DF. At present, there is an urgent need to carry out in-depth research on the source of pathogens, the investigation of epidemic foci, clinical science, antibody level in population, and sustainable control of Aedes vectors, and meanwhile, control of cross-border spread, mosquito control, and joint prevention and control in China-Myanmar, China-Laos, and China-Vietnam border areas are the key prevention and control measures that need to be strengthened at present.

Objective To establish a mosquito lamp sampling model based on Taylor's power law. Methods From April to November 2019, a total of 229 surveillance points of carbon dioxide trapping lamps were set up in 15 districts of Shanghai, China during every period of ten days to monitor the densities of Culex pipiens pallens and Aedes albopictus. The data were used to fit the Taylor's power law function equation: s ²= a× x^b, which described the relationship between the mean and variance of the density of every mosquito species in each period of ten days. The results derived from the equation were substituted into the sample size formula to establish the sampling model: n= t ²× a× x^{b -2}× D ^-2. The number of sample units needed for Cx. pipiens pallens and Ae. albopictus density surveillance was calculated at the 95% confidence level according to the sampling model. Results The fitting results of Taylor's power equation were as follows: a=5.847 8, b=1.525 4, and R ²=0.911 1 ( P<0.001) for Cx. pipiens pallens; and a=3.668 2, b=1.302 6, and R ²=0.962 0 ( P<0.001) for Ae. albopictus. The fitting results were entered into the sampling model, along with the value of t distribution and the D value of relative precision. The D value at the 95% confidence level for Cx. pipiens pallens was <0.35 during the middle ten days of April and during the first ten days of May to the middle ten days of November, and was <0.25 during the last ten days of May to the last ten days of August. The D value for Ae. albopictus was between 0.25 and 0.35 from the first ten days of July to the first ten days of October and during the last ten days of October, and was >0.35 during other periods. Conclusion This sampling model has practical significance and can be used to estimate the optimal sample size for light trap monitoring. The current mosquito surveillance method by carbon dioxide trapping lamps in Shanghai shows higher relative precision for Cx. pipiens pallens than Ae. albopictus. The relative precision for Ae. albopictus can be improved by increasing the number of light traps.

Objective To determine the killing effects of tetramethrin and dinotefuran mixtures on Blattella germanica, and to screen for the formula with a synergistic effect. Methods SPSS 22.0 software was applied to determine the regression equation of toxicity and median lethal concentration (LC ₅₀). The co-toxicity factor and co-toxicity coefficient were employed to evaluate the killing effects of tetramethrin and dinotefuran mixtures on B. germanica, and identify the optimal ratio of tetramethrin to dinotefuran. Results At 72 h after treatment, the LC ₅₀ values of tetramethrin and dinotefuran against the male adults of B. germanica were 1 376.86 mg/L and 3.97 mg/L, respectively. When the mass ratio of tetramethrin to dinotefuran was between 231:1 and 3 123:1, the mixture had a significant synergistic effect. The optimal mass ratio was 360:1, with a co-toxicity coefficient of 190.09 and an LC ₅₀ of 366.70 mg/L at 72 h after treatment. Conclusion The mixture of tetramethrin and dinotefuran shows a significant synergistic killing effect on B. germanica.

Objective To investigate the genotype of Yersinia pestis isolated from the natural plague focus of Meriones unguiculatus in Inner Mongolian Plateau using clustered regularly interspaced short palindromic repeats (CRISPR) and the difference in the genotype of strains from the same type of epidemic focus and different areas, to establish the CRISPR gene bank of plague strains from gerbil plague foci, and to lay a foundation for epidemiological trace-back and analysis of epidemic situation. Methods Three pairs of CRISPR primers (YPa, YPb, and YPc) were used for PCR amplification and sequencing of the DNA of experimental strains, and the CRISPR sequence obtained was compared with the latest CRISPR Dictionary reported in literature to obtain CRISPR spacer array and identify genotype. Bionumerics 7.6 software was used to plot clustering charts and analyze the phylogenetic relationship. Results A total of 9 spacers were found in 33 strains of Y. pestis, i.e., 4 types of YPa (a1, a2, a3, and a56), 2 types of YPb (b1 and b2), and 3 types of YPc (c1, c2, and c3). The comparative analysis showed that all strains were classified as 1 CRISPR gene cluster (Cb2) with two genotypes. The strains isolated from Etuoke banner and Hanggin Rear banner of Inner Mongolia were identified as a new genotype, which was named as genotype 2' (a1-a2-a3-a56, b1-b2, c1-c2-c3), and the strains from Urad Front banner of Inner Mongolia, Kangbao county of Hebei province, and Yinchuan city of Ningxia Hui autonomous region were identified as genotype 1 (a1-a2-a3, b1-b2, c1-c2-c3). Conclusion Y. pestis isolated from the plague foci of M. unguiculatus in Inner Mongolian is genetically stable as a whole and is classified as one gene cluster, but a certain degree of microevolution is observed, which reflects that strains from different areas have different genotypes.

Objective To investigate the transcriptome of Blattella germanica in response to low-temperature stress, the functional enrichment and metabolic pathways of low-temperature response genes, and the molecular mechanism of low-temperature response in B. germanica, and to improve the understanding of the molecular mechanism of temperature adaptation in B. germanica. Methods B. germanica adults were fed in this laboratory; B. germanica adults in the 25℃ were selected as controls, and transcriptome sequencing was performed for those placed in the 4℃ for 2 hours of low-temperature treatment to identify differentially expressed genes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to analyze the functional enrichment and metabolic pathways of genes. Results The sequencing data obtained 44 589 020 non-redundant transcripts, and calculation showed that 332 genes were upregulated and 371 genes were downregulated in response to low temperature. The low-temperature response genes were enriched into 27 GO terms and 35 KEGG metabolic pathways, including carboxylic acid metabolism, stress response, carbohydrate metabolism, neurotransmitter secretion, carbonate dehydratase activity, oxidoreductase activity, lyase activity, pyruvate dehydrogenase activity, pyruvate dehydrogenase complex, water transport, abiotic stress response, channel activity, multicellular tissue process, muscle membrane, plasma membrane, steroid hormone response, organic matter response, exopeptidase, protein metabolism, "P-P hydrolysis" kinesin transmembrane transporter activity, ER-targeted protein, hydrolase activity, nutrition storage activity, transferase activity, metal carboxypeptidase activity, lipid transporter activity, and cell division. Conclusion B. germanica may respond to low-temperature stress from 27 aspects including carboxylic acid metabolism and stress response, which provides a basis for clarifying the molecular mechanisms of response and tolerance to low temperature in B. germanica.

Objective To analyze the epidemiological characteristics of dengue fever and the surveillance data of Aedes vector in Hubei province, China, 2019, and to provide a basis for formulating effective prevention and control strategies for dengue fever. Methods The Breteau index method and double-net method were used to monitor the density of Aedes larvae and adults. Excel 2016 software was used to process and tabulate the data of dengue cases and mosquito vector surveillance. Results A total of 233 dengue cases were reported, including 30 cases of indigenous infections. Apart from Shennongjia forest region, all the other 16 cities (prefectures) had reported cases. There were reported cases all year round, with a peak period in June to November. Among all the reported cases, 87.12% (203 cases) were imported, and 81.36% (144 cases) of the imported cases were from Cambodia. The age of patients was mainly 20-54 years (193/233, 82.83%); farmers were the dominant occupation (73/233, 31.33%), followed by unemployed people (41/233, 17.60%). The ratio of males to females was 3.02:1. On average, they visited the hospital 6 days after onset. The peak density of Ae. albopictus occurred in June to October. Conclusion The dengue epidemic in Hubei province, 2019 was a local outbreak caused by imported cases. It is suggested that relevant departments should strengthen surveillance of the Aedes vector and dengue cases, so as to provide a scientific basis for the selection of local dengue prevention and control measures.

Objective To investigate the relationship between rodent fleas and meteorological factors in Meriones unguiculatus plague foci in Hebei province, China. Methods The monitoring data of rodent fleas from 2001 to 2013 and the meteorological data of precipitation, temperature, and humidity during the same period in M. unguiculatus plague foci in Hebei province were collected. According to the interquartile range, the data of precipitation, mean temperature, and mean relative humidity were all divided into four groups, and each four groups were compared in terms of flea infestation rate and flea index. A Spearman rank correlation analysis was used to analyze the correlation between these meteorological factors and flea infestation rate and flea index. Results There were significant differences in the distribution of flea infestation rate between different precipitation and mean temperature groups ( H=11.031 and 20.212, both P<0.05). When the precipitation was >60.40 mm and the mean temperature was >18.20℃, the flea infestation rate reached the peak level. There were significant differences in the distribution of flea index between different precipitation, mean temperature, and mean relative humidity groups ( H=8.044, 9.254, and 9.082, all P<0.05). When the precipitation was >60.40 mm, the mean temperature was 13.30-18.20℃, and the mean relative humidity was >64.00%, the flea index reached the peak level. The results of correlation analysis showed that flea infestation rate was positively correlated with precipitation and mean temperature ( r=0.396 and 0.547, both P<0.05), while flea index was positively correlated with mean temperature ( r=0.376, P<0.05). Conclusion Precipitation, mean temperature, and mean relative humidity are the important meteorological factors affecting the flea infestation rate and flea index in M. unguiculatus plague foci in Hebei province. Targeted flea control should be carried out according to the meteorological conditions.

Objective To investigate mosquito population variation in Jiangsu province, China from 2008 to 2018, and to provide a basis for mosquito control in Jiangsu province. Methods We collected adult mosquito surveillance data obtained using the lamp trapping method at provincial surveillance sites in Jiangsu from 2008 to 2018 to analyze mosquito population variation in urban and rural areas in Jiangsu. The pairwise Kruskal-Wallis test was used for statistical analysis. Results The mosquito density in urban areas, rural areas, and the whole province in Jiangsu from 2008 to 2018 was 7.53, 61.26, and 28.26 mosquitoes/light·night, respectively; in general, the annual mosquito density showed an increasing trend in urban areas, but a decreasing trend in rural areas and the whole province. In the three types of habitats in urban areas, i.e., residential areas, parks, and hospitals, parks were dominant habitats; in the two types of habitats in rural areas, i.e., civilian residences and livestock sheds, livestock sheds were dominant habitats, which were also absolutely dominant habitats among the five types of habitats mentioned above, with a mosquito density over seven times that in other four types of habitats. In the 11 years, the pooled mosquito density by month showed a single-peak variation in urban areas, rural areas, and the whole province, with a peak density in July (17.81, 235.23, and 101.95 mosquitoes/light·night, respectively, for the above three areas); in mosquito seasons, the mosquito density by month in rural areas was 1.50-13.20 times that in urban areas. The composition of mosquito populations in Jiangsu province was mainly Culex pipiens pallens, Cx. tritaeniorhynchus, Aedes albopictus, Anopheles sinensis, An. lesteri, and Armigeres subalbatus; Cx. pipiens pallens was the absolutely dominant species in urban areas; in rural areas and the whole province, the dominant species was Cx. tritaeniorhynchus in most of the 11 years and was Cx. pipiens pallens in the other few years. In most of the 11 years, the density of Cx. pipiens pallens in rural areas was about 2 times that in urban areas, with a significant difference between the two (χ²=15.783, P<0.01); in each of the 11 years, the density of Cx. tritaeniorhynchus in rural areas was over 10 times that in urban areas, with a significant difference between the two (χ²=15.783, P <0.01); the density of the two dominant species showed a single-peak seasonal variation, with a peak density in July. Except for the dominant species, the pooled density by month of other four species was higher in rural areas than in urban areas. Conclusion Remarkable achievements have been made in mosquito control in rural areas in Jiangsu province, while more efforts are needed in urban areas. The focus of mosquito control in rural areas should be livestock sheds and dominant mosquito species; effective surveillance of Ae. albopictus and Ar. subalbatus remains to be pushed forward. The pooled mosquito densities by year and month over the 11 years can provide a preliminary reference for the initiation of mosquito control in Jiangsu province.

Objective To investigate the common species and density of mosquitoes and their seasonal variation at vector surveillance sites in Heilongjiang province, China, and to provide a basis for risk assessment of mosquito-borne diseases and scientific development of mosquito prevention and control measures. Methods Mosquito surveillance data from 2007 to 2017 were collected from vector surveillance sites in Heilongjiang province; the data were compared for the differences in mosquito density between various species and habitats as well as their seasonal variation; Microsoft Excel 2016 software was used for statistical analysis. Results From 2006 to 2017, the total mosquito density was 2.26 mosquitoes/lamp·hour at the vector surveillance sites in Heilongjiang province; the mosquito species composition was dominated by Anopheles sinensis, accounting for 40.15% of the mosquitoes captured; the density of An. sinensis was highest, up to 0.91 mosquitoes/lamp·hour; the highest density was in livestock sheds (up to 6.12 mosquitoes/lamp·hour), followed by rural households (2.70 mosquitoes/lamp·hour); the seasonal variation in mosquito density of different species and habitats showed a single-peak trend, with the highest density in July and August. Conclusion Except for the density in 2007 (which is relatively high), the density of mosquitoes at the vector surveillance sites in Heilongjiang province from 2008-2017 shows a small-amplitude wavy decline; An. sinensis is the dominant species; the density is highest in rural areas, which are the key areas for mosquito prevention and control; mosquito activity peaks in July and August, which are the key periods for prevention and control measures.

Objective To investigate the epidemiological characteristics and infection sources of human brucellosis in Qinghai province, China, 2017-2019, and to provide a scientific basis for the prevention and control of brucellosis. Methods The data of brucellosis cases in Qinghai province from 2017 to 2019 were collected, as reported by the China Information System for Disease Control and Prevention. The descriptive epidemiological method was used to analyze the epidemiological characteristics. The isolated bacteria were cultured and identified to analyze the etiological characteristics. Results From 2017 to 2019, a total of 301 brucellosis cases were reported in Qinghai province, with an incidence of 0.45/100 000 in 2017, 1.81/100 000 in 2018, and 2.72/100 000 in 2019, with a significant difference between different years (t=16.421, P<0.05). The 301 cases were distributed in 26 counties (cities, districts), among which the top three counties (cities, districts) were Menyuan county (137/301, 45.51%), Dulan county (30/301, 9.97%), and Haiyan county (25/301, 8.31%). The age of onset ranged from 14 to 78 years, and the ratio of males to females was 3.63:1. Among the 301 cases, the top three occupations were farmers (31.89%), herdsmen (25.58%), and animal epidemic prevention personnel (20.27%); the mode of infection included livestock fattening and selling (108/301, 35.88%), rearing (97/301, 32.23%), animal epidemic prevention (61/301, 20.27%), processing (26/301, 8.64%), and food-borne infection (9/301, 2.99%). From 2018 to 2019, 37 whole blood samples with positive Rose Bengal plate agglutination test, colloidal gold immunochromatographic assay, and serum agglutination test were cultured, and 8 suspected strains were obtained, with a culture rate of 21.62%. The 8 strains of Brucella were identified as B. melitensis (cluster Ⅲ). Conclusion Currently B. melitensis (cluster Ⅲ) is the main epidemic strain causing human brucellosis in Qinghai province. And the prevalence of brucellosis in Qinghai province is on the rise. It is suggested that relevant departments should strengthen the control of sources of infection and take health promotion and other prevention and control measures among the high-risk population to control the occurrence and epidemic of brucellosis.

Objective To investigate overwintering Aedes albopictus eggs and the dengue virus carried by the eggs in the former dengue epidemic focus in Ningbo, Zhejiang province, China, and to provide scientific evidence for dengue control. Methods During December 2018 to March 2019, standing water and sludge in containers were collected from the former dengue epidemic focus (including the core area, warning area, and monitoring area) of Haishu district and three non-epidemic areas (Beilun district, Cixi city, and Ninghai county) in Ningbo, for incubation of Ae. albopictus eggs under laboratory conditions. Real-time RT-PCR was used to detect the dengue virus carried by the eggs. The chi-square test and logistic regression analysis were used to determine the influencing factors of the positive rate of overwintering Ae. albopictus eggs. Results A total of 884 samples were collected, and the positive rate of overwintering Ae. albopictus eggs was 11.99%. There were significant differences in the positive rate of overwintering Ae. albopictus eggs between different dengue control areas ( χ ²=31.227, P<0.001) and between different water containers ( χ ²=38.044, P<0.001). According to multivariate analysis, the positive rates for the warning area, monitoring area, and non-epidemic area were 5.33 (95% confidence interval[ CI]:1.16-24.49), 6.26 (95% CI:1.37-28.65), and 11.56 (95% CI:2.75-48.50) times that for the core area, respectively. The positive rates for waste tires and vegetative containers were 3.59 (95% CI:1.79-7.20) and 3.77 (95% CI:1.82-7.79) times that for stationary containers, respectively. All test results for the nucleic acid of dengue virus were negative. Conclusion The warning area and monitoring area of the former dengue epidemic focus, non-epidemic areas, waste tires, and vegetative containers are the main breeding sites for overwintering Ae. albopictus eggs. It is suggested that relevant departments should take timely measures focusing on the removal of standing water to control mosquitoes in early spring.

Objective To investigate the seasonal variation in the density of Aedes albopictus and its resistance to seven common insecticides at three national surveillance sites in Fujian province, China, and to provide a basis for formulating scientific strategies for dengue fever prevention and control as well as rational use of public health insecticides. Methods From March to December 2019, the density of Ae. albopictus at three national surveillance sites in Fujian province was monitored using the double-layered mosquito net method and Breteau index; the insecticide resistance of Ae. albopictus was determined using the larval dipping method and adult mosquito exposure tube method. Results At the three national surveillance sites in Fujian province, the annual mean net trap index was 3.93 mosquitoes/net·hour, and the mean Breteau index was 5.75; the density of Ae. albopictus reached a peak in June. The net trap indexes for old tire storage sites, recycling stations, and construction sites were 3.69, 3.77, and 4.32 mosquitoes/net·hour, respectively; the highest net trap index was observed at construction sites; among various types of water containers, idle containers had the highest positive rate (up to 45.92%). All Ae. albopictus larvae at the three national surveillance sites were sensitive to temephos; all adult mosquitoes (except for those in Xiamen, China which were sensitive to malathion and propoxur) showed varying degrees of resistance to seven common insecticides, namely, deltamethrin, permethrin, beta-cypermethrin, lambada-cyhalothrin, alpha-cypermethrin, malathion, and propoxur. Conclusion In the three national surveillance sites in Fujian province, the density of Ae. albopictus peaked one month earlier in 2019 than in 2018, and the mosquitoes developed varying degrees of resistance to the tested insecticides. It is of great significance to enhance the surveillance of the density and insecticide resistance of Ae. albopictus for rational use of insecticides, better prevention and control of mosquito-borne diseases such as dengue, and implementation of sustainable vector control strategies.

Objective To investigate the resistance of Blattella germanica to commonly used insecticides in ten districts of Shenzhen, China and the dynamic development rules of such insecticide resistance, and to provide a scientific basis for the drug control of cockroaches and the formulation of effective prevention and control programs. Methods According to the residual film method in Cockroach insecticide resistance monitoring program (On trial) formulated by National Study Group of Cockroach Prevention and Control, 2.5 ml of 0.05% insecticide solution was placed into a 500 ml transparent wide-mouth bottle, and the wide-mouth bottle was rolled to form a uniform drug membrane. The male adults of B. germanica were put into the bottle, and the knockdown of the test insects was observed and recorded at a certain interval. SPSS 24.0 software was used to calculate median knockdown time. Results Beta-cypermethrin showed high resistance in Longgang district, with a resistance ratio of 11.34, medium resistance in Bao'an, Guangming, and Futian districts, with resistance ratios of 8.79, 8.77, and 8.07, respectively, and low resistance in the other districts. Permethrin showed high resistance in Futian, Longhua, Bao'an, Longgang, and Luohu districts, with resistance ratios of 22.26, 13.99, 14.28, 13.01, and 10.01, respectively, medium resistance in Pingshan district, with a resistance ratio of 5.51, and low resistance in the other districts. Deltamethrin showed medium resistance in Bao'an, Longgang, and Longhua districts, with resistance ratios of 7.00, 6.39, and 6.02, respectively, and low resistance in the other districts. Cypermethrin showed high resistance in Bao'an district, with a resistance ratio of 19.65, medium resistance in Futian district, with a resistance ratio of 9.42, and low resistance in the other districts. Chlorpyrifos, acephate, and propoxur showed low resistance in all districts. Conclusion Varying degrees of resistance to pyrethroid insecticides are observed in B. germanica in Shenzhen. It is suggested to stop or restrict the use of insecticides with medium and high resistance and to use chlorpyrifos, acephate, and propoxur with low resistance. At the same time, comprehensive control measures should be taken to control and delay the development and progression of insecticide resistance in B. germanica.

Objective To analyze the resistance development of Aedes albopictus to commonly used insecticides in Wuxi, Jiangsu province, China from 2015 to 2019, and to provide scientific evidence for rational use of insecticides. Methods During 2015 to 2019, Ae. albopictus was collected by ovitrap method from the residential areas or parks of eastern, western, southern, northern, and central regions of Wuxi, and was reared to F1 generation in the laboratory. The larval dipping method was used to test the resistance level. Results The resistance ratio (RR) of Ae. albopictus larvae to beta-cypermethrin was 101.12 in 2015, 106.90 in 2017, 54.66 in 2018, and 26.12 in 2019. The RR to deltamethrin was 46.48 in 2015, 63.75 in 2017, 22.39 in 2018, and 13.86 in 2019. The RR to permethrin was 153.74 in 2015, 66.32 in 2017, 63.79 in 2018, and 37.53 in 2019. The resistance to beta-cypermethrin and permethrin was high from 2015 to 2018, but declined to a moderate level in 2019. The resistance to deltamethrin was high from 2015 to 2017, but declined to a moderate level from 2018 to 2019. The RR to temephos was 5.98 in 2015, 7.42 in 2017, 10.00 in 2018, and 2.35 in 2019. The RR to fenobucarb was 21.14 in 2018 and 5.64 in 2019. The resistance of the larvae to temephos changed from a low to moderate level then to a sensitive level. The resistance to fenobucarb was low or moderate. Conclusion Ae. albopictus in Wuxi shows moderate-to-high resistance to beta-cypermethrin, deltamethrin, and permethrin, and low-to-moderate resistance to temephos and fenobucarb. The resistance generally showed a declining trend in 2019. Rational use of insecticides should be advocated to delay the development of insecticide resistance. Avoid heavy usage of high-resistance insecticides and adopt the strategy of alternation, rotation, or mixing of insecticides.

Objective To investigate the current status of insecticide resistance of Aedes albopictus in Wuhu city of Anhui province, China, and to provide a scientific basis for formulating standard and rational strategies for the use of public health insecticides and the prevention and control of dengue fever. Methods The larval dipping method in the sensitive baseline method was used. The insecticides to be tested were diluted by acetone into a series of concentrations, and 1 ml was taken from each concentration and was prepared into 200 ml aqueous solution. A total of 20 IV-instar larvae were placed in each solution, and the number of deaths were observed 24 hours later. SPSS 20.0 software was used to calculate median lethal concentration (LC ₅₀), and the level of insecticide resistance was compared. Results A total of 2 760 Ae. albopictus larvae were tested, and the LC ₅₀ values of permethrin, deltamethrin, beta-cypermethrin, propoxur, and malathion were 0.054 142, 0.007 077, 0.020 922, 0.305 849, and 0.139 400 mg/L, respectively. The resistance ratios of Ae. albopictus larvae to permethrin, deltamethrin, beta-cypermethrin, and propoxur were 27.14, 17.69, 23.27, and 0.85, respectively, suggesting moderate resistance to permethrin, deltamethrin, and beta-cypermethrin and sensitivity to propoxur. Conclusion Ae. albopictus larvae in Wuhu are moderately resistant or sensitive to four commonly used insecticides. It is recommended to reduce the use of pyrethroid insecticides and use sensitive insecticides alternatively to delay the occurrence and development of insecticide resistance.

Objective To analyze the spatial-temporal distribution characteristics of Japanese encephalitis in Yunnan province, China, from 2009 to 2018, and to provide a basis for formulating the strategies of Japanese encephalitis prevention and control. Methods The data of Japanese encephalitis cases in Yunnan province from 2009 to 2018 were collected. Excel 2010 software was used to make statistics and plot the temporal distribution of Japanese encephalitis cases. ArcGIS 10.6 software was used to plot the spatial distribution of Japanese encephalitis cases. SaTScan 9.4.2 software was used to scan and analyze the spatial, temporal, and spatial-temporal distributions of Japanese encephalitis cases. Results A total of 2 091 cases of Japanese encephalitis were reported by 125 counties (districts) from 2009 to 2018. Via the spatial analysis alone, it was found that there were mainly five clusters of Japanese encephalitis cases, which were distributed in 33 counties of Xishuangbanna Dai autonomous prefecture, Pu'er city, Honghe Hani and Yi autonomous prefecture, Zhaotong city, Wenshan Zhuang and Miao autonomous prefecture, Dehong Dai and Jingpo autonomous prefecture, and Kunming city. Via the temporal analysis alone, it was shown that the Japanese encephalitis cases were concentrated in June to September. Via the spatial-temporal analysis, it was shown that there was only one cluster of Japanese encephalitis cases, which was mainly distributed in 8 counties of Zhaotong city, Daguan, Yongshan, Yanjin, Zhaoyang, Shuifu, Suijiang, Ludian, and Zhenxiong, and the cases were concentrated in August to September. Conclusion The incidence of Japanese encephalitis in Yunnan province had spatial-temporal clustering from 2009 to 2018, and it was mainly concentrated in the northeast of Yunnan province. The relevant departments in the northeast of Yunnan province should further strengthen the local Japanese encephalitis surveillance and prevention and control measures.

In this article, two new species from genera Xenodaeria Jordan (1932) and Rhadinopsylla Jordan et Rothschild (1912) (Siphonaptera:Ctenophthalmidae), collected from Linzhi, Tibet autonomous region of China, were described. (1) Xenodaeria houyongi sp. nov. Its main features are as follows:The frontal bristle consists of six spiniform bristles with deep ossification; in females, the depression of the posterior margin of sternum Ⅶ was small and shallow, the ventral lobe was wide and large and significantly longer than the dorsal lobe, and the height of the dorsal margin is significantly lower than that of the 7th spiracle; the depression of ventral margin at the bulga of spermatheca is located at the midpoint, and the hilla end has papillae. The holotype (only one ♀) was collected from the body of Crocidura dracula in a farming area (at an altitude of about 1 200 m) of Motuo county, Linzhi in December 2019. (2) Rhadinopsylla ( Actenophthalmus) linzhiensis sp. nov. Its main features are as follows:It has a total of 18 pronotal combs; in males, the movable process of clasper is straight and slender, with symmetrical front and rear margins; the sternum Ⅷ has only 2 bristles; the apex port of posterior arms at sternum Ⅸ has a series of spiniform bristles; the end of uncinate process of the aedeagus is finger-like. The holotype (only one ♂) was collected from the body of Ochtona sp. in a farming area (at an altitude of about 3 000 m) of Bayi town, Linzhi in November 2018.

Objectve To explore a grid-based model for vector mosquito surveillance, and to provide a scientific basis for surveillance and control of mosquito-borne diseases. Methods From July to October 2019, three subdistricts (including the natural paths within the subdistricts) in the north, middle, and south of Jing'an district, Shanghai, China were divided into adjacent surveillance blocks with an area of 400 m×400 m. The Breteau index (BI) and human-baited landing method were used to conduct on-site surveillance in blocks. The effectiveness of grid-based surveillance was evaluated by comparing the results of different geographical locations and surveillance blocks. Excel 2016 and SPSS 16.0 softwares were used for data processing, and statistical analyses such as Kruskal-Wallis rank sum test and Spearman correlation analysis were performed. Results A total of 21 surveillance blocks were demarcated and 8 rounds of surveillance were conducted. The langding index (LI) of Aedes albopictus was 4.06 mosquitoes/person·hour, with the highest value of 9.58 mosquitoes/person·hour in late July, followed by 7.62 mosquitoes/person·hour in mid-July and 5.62 mosquitoes/person·hour in mid-August; there was no significant difference in the LI between north, middle, and south areas ( Z=0.587, P=0.746). The mean BI was 27.21, with the highest value of 40.64 in mid-July, followed by 37.90 in late July and 35.56 in mid-August; the changes over time were basically the same as those of LI, with a significant difference between north, middle, and south areas ( Z=47.161, P<0.001). The LI and BI were counted in blocks, with significant differences between surveillance blocks; the most significant inter-block difference was observed in mid-July; the mean LI was 7.62 mosquitoes/person·hour, with the highest value of 29.00 mosquitoes/person·hour and the lowest value of 0 mosquito/person·hour; the mean BI was 44.07, with the highest value of 178.57 and the lowest value of 0; the difference between the surveillance blocks decreased gradually with decreasing density. There were significant differences in both LI and BI between different places ( Z=18.747 and 18.722, respectively, P=0.001 and 0.001, respectively), with the highest value in schools, followed by residential areas. Conclusion Mosquito density is affected by multiple factors such as the environment and the implementation of control measures. There are also differences in mosquito breeding in different places and regions. Therefore, it is recommended to expand the surveillance coverage by adopting grid-based surveillance model in vector mosquito surveillance, which will make the results more representative.

Objective To explore the standards and systematic assessment indices for "fly-free villages". Methods Based on relevant national standards and the experience obtained from creating three pilot "fly-free villages" in Zhejiang province, China, expert consultation combined with field investigation were used to explore the standards and systematic assessment indices for "fly-free villages". Results "Fly-free villages" were proactively created by all villagers on the initiative of the village branch committee and villagers' self-government committee based on the principles of voluntariness, self-creation, and self-management. A sustainable control strategy was proposed, namely, focusing on environmental prevention and control and integrating physical prevention and control. The final assessment indices of "fly-free villages" were as follows:adult fly density ≤ 0.5 fly/cage (cage trapping method), infestation rate of indoor adult flies ≤ 3.0%, indoor fly density ≤ 3.0 flies/room, and fly breeding rate ≤ 1.0%. The "fly-free villages" were organized and managed in a systematic way; villagers' awareness rate of fly prevention and control-related knowledge, villagers' actual participation rate, villagers' support rate, and villagers' degree of satisfaction were ≥ 90.0%. Conclusion The standards for creating "fly-free villages" are feasible in practice to some degree, which can provide a reference for the creation of "fly-free villages".

Objective To investigate the species distribution, species composition, blood-sucking rate, and light-trap index in the cattle pens in three northeastern provinces of China. Methods From 2010 to 2019, hematophagous midges were captured with light traps from cattle pens in 7 counties (cities) in three northeastern provinces of China. The Chi-square test was used to compare the blood-sucking rates. Results A total of 322 505 hematophagous midges were collected from 7 counties (cities) in northeast China, which belonged to 29 species from 2 genera, including 28 species of Culicoides and 1 species of Lasiohelea. Among them, Kuandian county had 19 species, Dongning city had 15 species, Xunke county had 15 species, Dunhua city had 8 species, Fuyuan county had 8 species, Qingyuan county had 6 species, and Ji'an city had 7 species. The dominant species were C. sinanoensis (38.42%) and C. punctatus (37.60%), and the species composition varied in different counties (cities). The overall blood-sucking rate of 9 main species in 4 counties (cities) was 54.63%. Specifically, C. orientalis had the highest blood-sucking rate (71.87%), and C. humeralis had the lowest (14.68%). The overall light-trap index in 5 counties (cities) was 4 788.98 midges/light·night. Specifically, Dunhua city had the highest light-trap index (9 499.94 midges/light·night), and Xunke county had the lowest (1 408.62 midges/light·night). The blood-sucking rate and light-trap index varied across different midge species and counties (cities). Conclusion There were 29 species from 2 genera of hematophagous midges in the cattle pens of 7 counties (cities) in three northeastern provinces of China. The dominant species were C. sinanoensis and C. punctatus. C. orientalis had the highest blood-sucking rate, and Dunhua city had the highest light-trap index.

Objective To analyze the weak links of vector prevention and control in the secret evaluation of healthy cities in China, and to propose the focus and direction of vector prevention and control in the establishment or consolidation of healthy cities. Methods The secret evaluation indicators for vector prevention and control in 35 national healthy cities (counties or districts) were retrospectively reviewed. With IBM SPSS 20.0 software, the correlation between the total score and the individual score of vector prevention and control was determined by Pearson correlation analysis. The scores of different cities were compared using the independent-samples t test. Results There was a positive correlation between the total score and the individual score of vector prevention and control ( r =0.812, P <0.001). No significant differences in the scores of vector prevention and control were found between prefecture-level cities and county-level cities ( t =0.375, P =0.710) and between established healthy cities and reexamined healthy cities ( t =1.506, P =0.141). Among the second-level indicators, two indicators of fly control and rodent control were where points were easy to lose. Among the third-level indicators, rodent bait station, anti-rodent facilities in key industries, facilities for fly control, fly breeding area control, adult fly density control, and mosquito breeding area control failed to meet the standard. Conclusion Vector prevention and control, where the management of vector breeding areas and the construction of anti-vector facilities are weak links, is closely related to other urban management work. Comprehensive mobilization, extensive publicity, health education, establishment of regulations, professional guidance, and improvement of facilities are the guarantee to consolidate the effects of vector control.

Objective To investigate the effect of different formulations and application methods of lambda-cyhalothrin in the control of Aedes albopictus in the field. Methods From August to October, 2019, relatively independent nursery gardens were selected in Huqiu district of Suzhou, and electrostatic and non-electrostatic sprayers were used to spray lambda-cyhalothrin in the forms of microcapsule suspension, wettable powder, and suspension on the vegetation with Ae. albopictus. At 1 week before spraying and within 6 consecutive weeks after spraying, the human-baited landing method was used to monitor the density of Ae. albopictus; at the same time, about 200 grams of leaves were collected per experimental plot every week, and gas chromatography-mass spectroscopy was used to monitor the change in drug residue on leaves after spraying. SPSS 16.0 software was used for statistical analysis of data; the chi-square test was used for comparison of rates, and the t-test or an analysis of variance was used for comparison of continuous data. Results Compared with the control group, the experimental groups achieved a reduction rate of >70.0% in Ae. albopictus density for 4-5 consecutive weeks after the spraying of lambda-cyhalothrin microcapsule suspension on hedgerow; the suspension achieved a reduction rate of >70.0% in Ae. albopictus density for 2 weeks, while the wettable powder achieved a reduction rate of >70.0% for only 1 week. The residue of microcapsule suspension remained between 7.2 mg/kg and 9.3 mg/kg within 4 weeks after spraying; at 1 week after spraying, the residue of microcapsule suspension with electrostatic sprayer was about 1.7 times that with non-electrostatic sprayer, and microcapsule suspension with electrostatic sprayer had a longer effective duration than that with non-electrostatic sprayer. Conclusion Pesticide application on hedgerow can effectively control the density of Ae. albopictus in the external environment. Microcapsule suspension has a significantly better control effect on Ae. albopictus than wettable powder and suspension, with an effective duration of 4-5 weeks. Electrostatic spraying can significantly improve the amount of drug residue on vegetation and thus enhance the control effect on Ae. albopictus.

Ticks are blood-sucking ectoparasites that release a variety of anticoagulant substances to their hosts to prevent blood clotting for the convenience of their blood feeding. Serine protease inhibitors containing Kunitz domain secreted by ticks are important anticoagulant substances. For different ticks, various anticoagulant substances are produced in different organs targeting their specific coagulation factors at different binding sites. This article reviews the existing tick-derived anticoagulant substances containing the Kunitz domain, so as to provide a reference for discovering more such anticoagulant substances in tick origin in the future and studying the mechanism of tick-host interaction at the pharmacological level.

Chagas disease (also known as American trypanosomiasis) is a zoonosis caused by the flagellate protozoa trypanosomiasis, and the transmission of this disease depends on the blood-sucking insects belonging to Triatominae, Reduviidae, Hemiptera. This subfamily currently contains 154 species, which are widely distributed in various countries around the world. Triatominae species with different living habits and tolerance levels have different distribution ranges, and correct taxonomy can construct the global distribution range of different species, so that targeted measures can be taken to control Chagas disease to the greatest extent. Traditional taxonomic identification mainly relies on morphological observation, but for some species with great similarity in morphological characteristics, the dependence on morphological identification alone often leads to some errors, and in this case, genetic methods with higher accuracy are needed for confirmation. Genetic methods include cytogenetics and molecular genetics, and with the advantages of convenience, low costs, and accuracy, cytogenetics has become the most commonly used method for the taxonomic identification of Triatominae species.

Phototaxis, chromatics tropism, and chemotaxis are the main behavioral characteristics of disease vectors and play important roles in the life activities of vectors. At present, induced killing and repelling techniques based on tropism have been widely used in vector monitoring and control. With in-depth studies on tropism in recent years, various technologies are gradually improved and optimized and are developing along the direction of high efficiency, strong specificity, and environmental protection. This article reviews the data on the research and application of vector tropism published in the recent 20 years, summarizes the research advances in common tropisms of vectors and their application in the control of vectors such as mosquitoes, flies, rodents, and cockroaches, and points out current problems and shortcomings and the future prospects and directions of tropism research, in order to provide a reference for better application of vector tropism in prevention and control.

Objective To study the spatial stability of vector abundance of Aedes albopictus in Shanghai, China, and to provide a basis for prevention and control of dengue fever. Methods From May to November 2019, sub-district/township-based surveillance of Ae. albopictus density was carried out in Shanghai using mosquito ovitraps. The global spatial autocorrelation Moran's I index was calculated to determine the spatial clustering pattern in the whole study area. Spearman's correlation coefficient was used to determine the correlation between the positive rates of mosquito ovitraps in administrative areas or sub-district/townships at different times. Kendall's coefficient of concordance (Kendall's W) was calculated to measure the agreement between rank orders of positive rates of mosquito ovitraps at different times. Results In 2019, the highest, lowest, and median mean positive rates of mosquito ovitraps per year were 8.70%, 1.88%, and 5.46%, respectively, for each administrative area in Shanghai, and were 30.21%, 0, and 5.51%, respectively, for each sub-district/township. Spatial analyses showed that the density of Ae. albopictus was higher in the west and north of the city. The Spearman's correlation coefficients on sub-district/township and administrative area scales were greater for 1 week before as compared with those for 3 weeks before and were greater for 3 weeks before as compared with those for 6 weeks before; the Spearman's correlation coefficients on an administrative area scale were greater than those on a sub-district/township scale. During the study period, the Kendall's W of positive rates of mosquito ovitraps was 0.627 in a sample unit of administrative areas ( χ ²=197.542, P<0.001), and was 0.436 in a sample unit of sub-districts/townships ( χ ²=1 802.154, P<0.001). Conclusion The spatial stability of positive rates of mosquito ovitraps on an administrative area scale is better than that on a sub-district/township scale. Therefore, attention should be paid to sub-districts/townships with abnormal density changes while the prevention and control measures are strengthened in administrative areas with a high density of Ae. albopictus.

Objective To establish a RT-hemi-nested PCR assay for laboratory detection of mosquito-borne alphaviruses based on the universal primers of mosquito-borne alphaviruses. Methods Three universal primers of mosquito-borne alphaviruses were designed in the conserved regions based on the whole genome sequence of alphaviruses in GenBank. The RT-hemi-nested PCR assay was established using the cDNAs of Sindbis virus (SINV) and Chikungunya virus (CHIKV) as templates under optimized conditions; the sensitivity and specificity of this method were validated and mosquitoes collected in the field were tested. Results The sensitivity test results showed that the lowest detection limit of SINV and CHIKV was 3×10 ³ and 3×10 ⁴ copies/µl. The sensitivity test results showed that the RT-hemi-nested PCR was only able to amplify the alphavirus. The established method was used to detect mosquito specimens collected in the field. The results showed that mosquito-borne alphavirus was not detected in all samples . Conclusion The RT-hemi-nested PCR assay established in the study is highly specific and sensitive and can be used for epidemiological survey on alphavirus infection.

Objective To investigate whether Haemaphysalis longicornis can transovarially transmit the spotted fever group Rickettsia (SFGR) new genotype Candidatus Rickettsia longicornii. Methods Feeding H. longicornis was collected from cattle body surfaces and induced to oviposit in the laboratory. The polymerase chain reaction was used to detect the nucleic acid of Candidatus R. longicornii in tick eggs. The gene sequences of Candidatus R. longicornii in the mothers and eggs of H. longicornis were amplified. An analysis was performed on the homology and phylogenetic relationship. Results A total of 55 feeding H. longicornis (adult female ticks) were collected, among which 21 (38.18%) were positive for Candidatus R. longicornii according to the nucleic acid test. About 2 500 H. longicornis eggs were collected and divided into 50 groups, of which 6 groups were positive for Candidatus R. longicornii. The minimum infection rate was 0.24% in tick eggs. The homology analysis showed that the gene sequences of Candidatus R. longicornii from H. longicornis mothers and eggs had more than 99.79% homology with that of the tick-derived ROK-HL727 strain first found in South Korea. The Candidatus R. longicornii gene sequence homology between H. longicornis mothers and eggs was over 99.69%; the gene sequences were in the same branch and had close phylogenetic relationships with that of the ROK-HL727 strain. Conclusion The infection rate of H. longicornis mothers with the SFGR Candidatus R. longicornii genotype is relatively high, and the genotype can be transovarially transmitted.

Objective To implement sustainable vector control strategies and measures for Japanese encephalitis (JE) by carrying out integrated mosquito prevention and control (IMPC) in developing rural areas of Gansu province as a health, poverty alleviation, and public welfare activity in 2019, and to provide a IMPC package for mosquito control in high-prevalence areas of JE in China. Methods The activity was jointly proposed by professional institutes and social organizations, technically guided by disease control specialists, and implemented by several enterprises and voluntary teams engaged in pest control operation (PCO). Zhaoshi village in Bali town, Jingning county, Pingliang, Gansu province, with the highest incidence rate of JE in 2017, was selected, and integrated management strategies were carried out, including public education for villagers, thorough elimination of mosquito larvae breeding sites, and chemical control in key areas. During the activity, the lamp trapping method was used to monitor the change in mosquito density to evaluate the effect of integrated mosquito control. Results A total of 41 enterprises participated in the activity, and 19 technical specialists and 37 PCO volunteers formed the team of volunteers. Investigation before control showed that bonsai, aquatic plants, cisterns, tanks, and basins were the main containers for water accumulation, with a positive rate of water accumulation of 34.32% and a 100-household index of 85.33. Main mosquito breeding sites in the external environment within and around the village included pipe wells, sewer water, open channels, sewage lagoons, unused bowls/bottles/tanks/cans, and waste tires, with a positive rate of 17.31%. The results of monitoring before control showed that the density of adult mosquitoes was 50.33 mosquitoes/trap/night, and Culex tritaeniorhynchus was the dominant species accounting for 80.13%, followed by Cx. pipiens pallens accounting for 12.91% and Anopheles sinensis accounting for 5.96%. After the first time of prevention and control, the density of adult mosquitoes was reduced to 11.60 mosquitoes/trap/night, with Cx. pipiens pallens accounting for 43.11%, Cx. tritaeniorhynchus accounting for 17.24%, An. sinensis accounting for 5.17%, and other mosquito species accounting for 34.48%, and the mean reduction rate of mosquito density was 76.95%. After the second time of prevention and control, the total mosquito density was reduced to 6.67 mosquitoes/trap/night, with An. sinensis accounting for 42.50%, Cx. pipiens pallens accounting for 17.50%, Cx. tritaeniorhynchus accounting for 15.00%, and other mosquito species accounting for 25.00%; the mean reduction rate of mosquito density was 86.75%, and the reduction rate of peasant households reached 100%. With the implementation of integrated mosquito prevention and control measures, the composition ratio of Cx. tritaeniorhynchus decreased from 80.13% to 15.00%. There was a significant reduction in mosquito larvae breeding sites after on-site public education and treatment, with a reduction rate of 93.24% based on container index. Conclusion The sustainable mosquito control mode of monitoring, control, and evaluation has a good effect in spreading the knowledge of mosquito prevention and control and reducing mosquito density and can be widely used in the high-prevalence areas of JE in China. Such measures should be taken in accordance with local conditions to achieve a better effect.

Objective To investigate mosquito in Yunnan province, China, as well as the population density, distribution, regional differences, and breeding habits of Aedes aegypti and Ae. albopictus in main urban areas. Methods Breteau index (BI) was used to investigate Aedes in the main urban areas of 129 counties, cities, and districts of Yunnan province, and all water containers in residential areas and special places (including park and green spaces in the urban area, recycling stations, tire collection stations, and hospitals) were checked. Water containers infested with larvae or pupae of Aedes vector were marked as positive, and the larvae in positive containers were collected and morphologically identified. Descriptive statistics was used to describe general information; the Chi-square test was used to investigate the difference in Aedes breeding sites between different areas and ecological environments, and the Chi-square test for trend was used to investigate the association between altitude and mosquito breeding density. Results Among the 129 counties, cities, and districts of Yunnan province, 71 (55.04%) were found to have Aedes vector, among which 68 (52.71%) were found to have Ae. albopictus alone and 3 (2.33%) were found to have both Ae. aegypti and Ae. albopictus. A total of 37 198 households were investigated, among which 1 068 households were positive for Aedes; a total of 167 206 water containers were found, among which 2 135 were positive, with a mean BI of 5.74, a house index of 2.87%, and a container index (CI) of 1.28%. Special places had significantly higher BI and CI than residential areas ( χ ²=4 509.220 and 128.591, both P<0.001). Tires were the most common type of water container and accounted for 44.84%, followed by other temporary containers (12.55%) and buckets (13.64%). Tires had the highest positive rate of 1.73%, followed by buckets (1.25%), other temporary containers (1.02%), waste bottles (0.95%), pool (0.59%), other permanent containers (0.56%), and vase (0.48%). In terms of water containers, Dehong Dai and Jingpo autonomous prefecture had the highest positive rate of 8.72% (583/6 689), followed by Honghe Hani and Yi autonomous prefecture (285/10 053, 2.83%), Xishuangbanna Dai autonomous prefecture (124/4 587, 2.70%), Wenshan Zhuang and Miao autonomous prefecture (271/10 662, 2.54%), and Pu'er city (308/12 691, 2.43%). Among the 2 135 positive containers, 1 849 (86.60%) were found to have Ae. albopictus, 251 (11.76%) were found to have Ae. aegypti, and 35 (1.64%) were found to have both Ae. albopictus and Ae. aegypti. The composition of Ae. aegypti was 79.66% in Mengla county, 67.03% in Ruili city, and 34.55% in Jinghong city, and there was a significant difference between them ( χ ²=28.194, P<0.001). The Chi-square test for trend showed a linear relationship between Aedes breeding rate and altitude ( χ ²=1 413.993, P<0.001), and Aedes breeding rate gradually decreased with the increase in altitude. Conclusion Ae. albopictus is widely distributed in Yunnan province and Ae. aegypti has become the dominant species in some areas. Special places have a higher breeding rate of Aedes than residential areas, and border regions tend to have a high mosquito density. The density of Aedes vector gradually decreases with the increase in altitude, and no Aedes breeding is observed in the places with an altitude above 2 000 m. Buckets, tires, and waste cans are the main contributors for Aedes breeding in residential areas, while tires and other waste containers are the main contributors for Aedes breeding in special places.

Objective To provide a scientific statistical method for accurate determination of the seasonal density of plague host animals. Methods The data of Spermophilus dauricus were collected using Excel 2013 software from a natural plague focus monitoring site in Kangbao pasture in Hebei province, China from April to October in 2015-2019. The seasonal density of S. dauricus was analyzed by the concentration method. Results From 2015 to 2019, a total of 240 S. dauricus individuals were captured in an area of 490 hm ², and the mean annual density in Kangbao pasture was 0.49 inds/hm ². The highest density was 0.66 inds/hm ² in summer, followed by 0.37 inds/hm ² in Autumn and 0.18 inds/hm ² in winter. The highest density was recorded in April 2016 (2.53 inds/hm ²), followed by 1.94 inds/hm ² in April 2015 and 1.07 inds/hm ² in July 2018. Analysis with the concentration method showed M=0.330 5, suggesting that the density of S.dauricus varied across seasons. Conclusion The concentration method can accurately determine the seasonal density of S. dauricus as a plague host, and the highest density is found in summer, followed by autumn.

Objective To investigate the species composition, quantitative distribution, and seasonal variation of rodents and their parasitic fleas in the Zhangjiakou 2022 Winter Olympic Games zone (hereinafter referred to as the Zhangjiakou competition zone) and the surrounding areas in Hebei province, China, and to provide basic data for the prediction and emergency treatment of vector-borne diseases during the Winter Olympic Games. Methods From September 2018 to September 2019, the five-meter traping method and the quadrat method were used to investigate the species composition and density of rodents in Chongli district and the area around the Zhangjiakou competition zone, and parasitic fleas were collected and classified. The ecological method was used to analyze the species composition, distribution, and seasonal density variation of rodents, and Excel 2010 software was used to analyze data and draw charts. Results The quadrat method was used to investigate 20 quadrats, and no rodents were captured. The five-meter traping method was used to investigate 166 sites, and 266 rodents were captured by 16 600 traps and were classified into 8 species, 5 genera, and 3 families, with a capture rate of 1.60%. Time variation showed a rodent density of <1.00% from October to June in the next year, especially from December to April in the next year. Apodemus agrarius and Cricetulus barabensis were the main rodent species, and the rodent density was 6.14% in July and 5.93% in September. There was a variety of rodent species, mainly A. agrarius, C. migratorius, C. barabensis, A. peninsulae, and A. draco. A total of 266 rodents were examined, among which 36 were found to have fleas, with a flea infestation rate of 13.53%, and a total of 100 fleas were collected and classified into 7 species, 5 genera, and 3 families, with a mean flea index of 0.38. Bacteriological and serological tests were performed for all materials and yielded negative results. Conclusion Main host animals and fleas in Hebei province and surrounding natural plague foci are not found in the Zhangjiakou competition area and the surrounding area, and there are differences in natural landscape, the species composition of rodents, and the composition of fleas between the Zhangjiakou competition zone and natural plague foci in Hebei province. Therefore, there is a relatively low risk of primary animal plague in the local area.

Objective To study the rodent and cockroach infestations in underground tube wells in Beijing, China, and to provide a scientific basis for prevention and control strategies. Methods A total of 100 streets were selected in Beijing in 2019, and 50 underground tube wells were selected randomly in each street for monitoring (four times). Bait stealing and visual inspection were used for rodent and cockroach density monitoring, respectively. The data were recorded in Excel 2007 software, and a descriptive analysis was conducted. Results Among all the underground tube wells selected in Beijing, the mean value of rodent positivity was 1.06%, and the mean value of cockroach positivity was 0.04%. The number of rodent-positive tube wells was highest (28) in Chaoyang and Haidian districts and lowest (2) in Shunyi district. There were 7 cockroach-positive tube wells, 3 in Fengtai district, 3 in Xicheng district, and 1 in Dongcheng district. Compared with the rural areas, the urban areas had a higher rodent-positive rate of tube wells. Sewage wells had the highest rodent-positive rate (46.92%), followed by electric wells (26.07%) and other wells (12.79%). The main cockroach-infested wells were sewage wells, rainwater wells, and electric wells. Conclusion Varying degrees of rodent infestation were found in the underground tube wells of Beijing in 2019, more severe in the urban areas than in the rural areas. Some administrative divisions had cockroach infestation. Rodent prevention and control in underground tube wells must not be overlooked, and cockroach infestation in underground tube wells should also be closely monitored.

Objective To investigate the seasonal fluctuation of mosquito density in Liaoning province, China, and to provide a scientific basis for mosquito control and risk assessment, early warning, and prevention and control of mosquito-borne diseases. Methods From 2014 to 2018, mosquito density was monitored by the lamp trapping method from May to October in five mosquito habitats within urban areas (residential areas, parks, and hospitals) and rural areas (rural households and livestock sheds) of Liaoning province. Mosquito composition, density, and seasonal fluctuation were analyzed. Results From 2014 to 2018, a total of 7 000 mosquito traps were set up in Liaoning province and 275 736 mosquitoes were caught. In terms of mosquito species composition, Culex pipiens pallens, Anopheles sinensis, and Cx. tritaeniorhynchus were the top three, accounting for 24.59%, 21.01%, and 19.06% of the total mosquito counts, respectively. The overall mosquito density was 19.70 mosquitoes/lamp·hour. From 2014 to 2018, the mosquito density in each year was 16.75, 26.05, 15.83, 20.23, and 19.65 mosquitoes/lamp·hour, respectively. In terms of mosquito habitats, livestock sheds had the highest mosquito density (72.60 mosquitoes/lamp·hour), while hospitals had the lowest (2.40 mosquitoes/lamp·hour). In each year, the overall mosquito density fluctuated seasonally with a single peak in early or late August. Conclusion For mosquito control in Liaoning province, livestock sheds and rural households are the key places and the May to October period is the key time. Vector mosquito surveillance at each surveillance site should continue to be strengthened to provide a basis for the sustainable control of mosquitoes and mosquito-borne infectious diseases.

Objective To investigate the epidemiological characteristics of dengue fever (DF) and the distribution characteristics of Aedes vector mosquitoes in Dehong Dai and Jingpo Autonomous Prefecture (Dehong prefecture) of Yunnan province, China in 2013-2019. Methods The descriptive epidemiological method was used to analyze the data of DF cases. Breteau index (BI) was used to monitor the density of Aedes larvae, and species identification was performed for the mosquitoes collected. Results A total of 4 974 confirmed DF cases were reported in Dehong prefecture in 2013-2019, with 2 504 (50.34%) imported cases and 2 470 (49.66%) indigenous cases. The mean annual incidence rate was 56.23/100 000, with the highest incidence rate of 112.61/100 000 in 2019. The prevalence of DF was observed in Ruili, Mangshi, Longchuan, Yingjiang, and Lianghe counties/cities of Dehong prefecture; the cases in Ruili accounted for 88.18% (4 386/4 974) of all cases in Dehong prefecture, with a mean annual incidence rate of 320.93/100 000 and an annual incidence rate as high as 661.45/100 000 in 2019; the cases in the other 4 counties/cities accounted for 11.82% (588/4 974). Imported cases from Myanmar were reported in each month, mainly from July to December, while indigenous cases only occurred from June to November, with a peak in September and October. The age of patients ranged from 5 months to 92 years, mainly 20-49 years, and the male/female ratio was 1.06:1. As for occupation, 41.86% were business service providers, 17.01% were engaged in housework or were unemployed, 11.58% were students, and 9.28% were farmers. Family clusters were observed in 403 households involving 992 cases in Ruili. As for mosquito density in Ruili in 2013-2019, BI was 10-45 from June to November and <5 in the other months. Among the 39 469 larvae collected in 2019, Ae. aegypti accounted for 47.80%, Ae. albopictus accounted for 29.25%, and other mosquito species accounted for 22.95%. Ae. aegypti was mainly distributed in Ruili city, Zhangfeng town of Longchuan county, Labang town of Yingjiang county, and Manghai and Zhefang towns of Mangshi city, and Ae. albopictus was widely distributed in Dehong prefecture. Conclusion Both imported and indigenous DF cases are reported in Dehong prefecture in 2013-2019, and imported cases from Myanmar are the main cause of local prevalence of DF in Dehong prefecture. The epidemic areas of DF in Dehong prefecture are consistent with the distribution of Ae. aegypti, and the seasonal distribution of DF cases is closely associated with the increase in mosquito density. Strengthening the surveillance and management of the cross-border transmission of DF along the Sino-Myanmar border and conducting regular mosquito control are the key measures to control DF in this region.

Objective To investigate the distribution of Bartonella in different tissues of rodents with natural infections. Methods The night trapping method was used to capture rodents around Mishan Port of Heilongjiang province, China in May 2018. The heart, liver, spleen, lung, and kidney were homogenized and incubated, and Bartonella DNA was extracted from suspected colonies. Citrate synthase gene ( gltA) was PCR-amplified and sequenced to determine the species of Bartonella. The infection rates of these tissues were analyzed and compared. Results A total of 81 rodents of seven species were captured, including Apodemus agrarius (68, 84.0%), Microtus fortis, M. maximowiczii, Tamias sibiricus, and others. Bartonella strains were isolated from 45 rodents of four species, with an overall infection rate of 55.6%. The infection rates of the heart, liver, spleen, lung, and kidney were 38.3% (31/81), 39.5% (32/81), 42.0% (34/81), 32.1% (26/81), and 45.7% (37/81), respectively, which were not significantly different from each other ( χ ²=5.623, P=0.229). The 45 isolates were identified as seven species of Bartonella, i.e., B. grahamii, B. heixiaziensis, B. japonica, B. coopersplainsensis, B. taylorii, B. washoensis, and a novel species. B. grahamii was the predominant species (73.3%) and was isolated from multiple tissues, though the differences were not statistically significant ( χ ²=7.492, P=0.112). Conclusion Bartonella has a high natural infection rate in rodents and can invade various tissues with similar tissue tropism, and the infection is not constrained by host and Bartonella species.

Objective To investigate mosquito population distribution and mosquito virus infection in Wudu district, Longnan, Gansu province, China, and to provide a scientific basis for prevention and control of mosquito-borne infectious diseases. Methods Adult mosquito density was monitored in Wudu district from 2017 to 2019 using the light trapping method. Specific real-time PCR was used to detect Japanese encephalitis virus (JEV) and West Nile virus (WNV) in captured mosquitoes. Results A total of 15 796 female mosquitoes were captured from 2017 to 2019. The dominant species were Culex pipiens pallens (49.30%) and Cx. tritaeniorhynchus (45.59%). The mosquito density was highest in livestock sheds (104.76 mosquitoes/light·night). Cx. tritaeniorhynchus was the most abundant in livestock sheds (77.96%), followed by farmhouses (9.17%). The annual mean mosquito density increased continuously, and the differences were statistically significant ( χ ²=32.955, P<0.05). Mosquito density showed unimodal distribution and peaked in June to August, with the highest density in July 2019 (143.05 mosquitoes/light·night). The number of Cx. tritaeniorhynchus captured from June to August accounted for 92.20% (6 639/7 201) of the total number of this species. A total of 28 specimens were made from the 1 074 female mosquitoes captured from July 29 to 30, 2019 and sent to the Virus Laboratory of the Chinese Center for Disease Control and Prevention for nucleic acid detection of JEV and WNV, and the positive rates of JEV and WNV were 21.43% (6/28) and 0, respectively. Conclusion The density of mosquito vectors in Wudu district was relatively high, the proportion of Cx. tritaeniorhynchus increased from 2017 to 2019, and JEV was detected in mosquitoes. The high risk of mosquito-borne infectious diseases requires intensified mosquito control measures to reduce mosquito density and effectively suppress the occurrence of mosquito-borne infectious diseases.

Objective To analyze the resistance of Blattella germanica to commonly used insecticides in Wuxi, Jiangsu province, China in the past 10 years. Methods Every two years from 2010 to 2018, B. germanica was captured by electric suction device and mechanic trapping devices in farmer's markets, restaurants, and food trading centers in Wuxi. Captured cockroaches were brought back to the laboratory, reared for one generation, and insecticide resistance was measured by the residual film method. Results The resistance ratio (RR) of B. germanica to beta-cypermethrin was 8.25 (2010), 9.94 (2012), 5.78 (2014), 12.39 (2016), and 6.06 (2018). The RR to deltamethrin was 14.02 (2012), 6.27 (2014), 16.75 (2016), and 10.79 (2018). The RR to propoxur was 1.75 (2010), 1.48 (2012), 1.32 (2014), 2.53 (2016), and 1.24 (2018). The RR to acephate was 2.14 (2010), 1.31 (2012), 1.01 (2014), 1.03 (2016), and 0.76 (2018). The RR to chlorpyrifos was 0.91 (2014), 2.09 (2016), and 0.39 (2018). Conclusion The resistance of B. germanica to beta-cypermethrin and deltamethrin increased from 2010 to 2018 in Wuxi, with medium to high levels of resistance; the resistance to propoxur, acephate, and chlorpyrifos decreased slowly and showed overall sensitive to low levels of resistance.

Objective To analyze the epidemiological characteristics of Japanese encephalitis (JE) in eight provinces and municipalities of northern China (Gansu, Ningxia Hui Autonomous Region, Shaanxi, Shanxi, Hebei, Beijing, Tianjin, and Liaoning) from 2005 to 2019, to investigate the pattern of the development of JE, and to provide a scientific basis for effective prevention and control of JE. Methods A descriptive epidemiological analysis was performed for JE cases in the above eight northern provinces and municipalities from 2005 to 2019, which were collected through the China Information System for Disease Control and Prevention and JE Surveillance Information Reporting and Management System. Results From 2005 to 2019, the mean annual incidence rate of JE was 0.14/100 000 and there were 390 deaths, with a case fatality rate of 7.25%. The distribution of JE expanded from 157 counties/districts in 2005 to 254 counties/districts in 2018. The number of cases from August to September accounted for 81.26% of all cases, and August and September were the peak periods for the onset of JE. The proportion of patients aged 0-14 years decreased from 54.55% in 2005 to 3.96% in 2019, and the proportion of patients aged ≥ 15 years increased from 45.18% in 2005 to 96.03% in 2019 ( χ ² _trend=998.524, P<0.001). Farmers, preschool and scattered children, and students accounted for 58.76%, 14.81%, and 12.38%, respectively. The proportion of farmers increased from 37.19% in 2005 to 79.21% in 2019. Conclusion The distribution of JE has expanded in the eight provinces and municipalities of northern China, and age distribution tilts toward high age. As for occupational composition, there is an increase in the proportion of farmers.