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.

Objective To investigate the effective protection time against Aedes albopictus of different concentrations of new mosquito repellent solution dissolved by different concentrations of ethanol, and to determine a suitable ethanol concentration for repellent formulation with an appropriate repellent concentration. Methods According to "Laboratory efficacy test methods and criterions of public health insecticides for pesticide registration-Part 9:Repellent" (GB/T 13917.9-2009), the stock solution of the new mosquito repellent was diluted to gradient concentrations separately with 75% ethanol (15%, 10%, and 8% repellent solutions) and 35% ethanol (8% repellent solution). Results The effective protection time of 8% repellent was 4.63 h when it was prepared with 75% ethanol, and 3.74 h with 35% ethanol. With 75% ethanol as the solvent, the effective protection time was prolonged with the increase of the effective concentration of the new mosquito repellent formulation, being 4.63 h, 5.42 h, and 6.10 h for 8% repellent, 10% repellent, and 15% repellent, respectively. Conclusion Seventy-five percent ethanol is a suitable solvent for the stock solution of the new mosquito repellent, and the repellent effect against Ae. albopictus is good at an effective concentration of 15%.

Objective To explore the spatial characteristics and correlations of different types of dengue cases in key epidemic areas of dengue fever in mainland China. Methods Spatial visualization technology was used to analyze the spatial characteristics of dengue cases in Guangdong and Yunnan provinces from 2014 to 2018, and the Spearman correlation method was used to explore the correlations between different types of dengue cases. Results Dengue cases in the study area were mainly concentrated in Guangdong and Yunnan province from 2014 to 2018, there were 46 306 indigenous dengue cases, 2 304 overseas imported dengue cases, 79 domestically imported cases, and 625 domestically exported cases. Guangzhou of Guangdong province had the most indigenous cases (39 656). Ruili of Dehong Dai and Jingpo autonomous prefecture (Dehong prefecture) in Yunnan province had the most overseas imported cases (1 640). The main source of overseas imported cases came from Southeast Asia, the most of which came from Myanmar, reaching 1 876 cases. Domestically exported cases mainly came from Guangzhou, reaching 457 cases, which were distributed all over southern provinces of China. Indigenous cases were highly positively correlated with domestically imported cases and domestically exported cases, with coefficients of 0.811 and 0.933, respectively. In Ruili, Dehong prefecture, Yunnan province, the indigenous cases were highly correlated with overseas imported cases. Conclusion Dengue cases were concentrated in Guangdong and Yunnan provinces. Indigenous cases were highly correlated with domestically imported cases and domestically exported cases. The research findings are helpful for providing strategic prevention and control programs and taking effective measures for dengue prevention and control.

Objective To evaluate the effect of ultra-low-volume spraying using unmanned aerial vehicle (UAV) in mosquito control in urban residential areas, and to provide a basis for the prevention and control of mosquitoes and mosquito-borne diseases. Methods Two comparable residential areas (villages) were selected in Pujiang county, Zhejiang province, China, from July 15 to 27, 2017. One area applied UAV-based ultra-low-volume spraying to kill mosquitoes for five rounds with an interval of three days, while the other area served as a control. Adult mosquito density surveillance by mosquito trap lamps for the two areas started three days before UAV spraying and continued till 15 days after five rounds of spraying. The changes in mosquito density were compared between the two areas for evaluating the mosquito-killing effect of UAV spraying. The decline rate of mosquito density was calculated based on the mean value of every three days. Results After the first round of UAV spraying, in the spraying area, the number of female mosquitoes decreased by 41.71%, male mosquitoes by 4.12%, and total mosquitoes by 27.10%. Fifteen days after five rounds of UAV spraying, the number of female mosquitoes, male mosquitoes, and total mosquitoes declined by 44.34%, 20.96%, and 35.69%, respectively. Conclusion Ultra-low-volume spraying by UAV is an effective method to kill mosquitoes in urban residential areas, and will be widely used control of mosquito-borne diseases as technology develops.

Objective To investigate the species, density, and spatio-temporal characteristics of cockroaches in human habitats and surroundings in China and the cockroach surveillance results based on the sticky trap method and visual observation, and to provide a scientific basis for cockroach prevention and control. Methods The cockroach surveillance data were collected from the national surveillance sites for vectors in China, 2019. Excel 2013 software was used to analyze the cockroach distribution characteristics of different species in different habitats, in different provinces, and at different times. Results In 2019, the surveillance results according to the sticky trap method showed that the sticky trapping rate was 5.45% and the infestation rate was 5.25%. Blattella germanica was the dominant species, accounting for 95.65% of the total catch, Periplaneta americana accounted for 2.42%, and the rest accounted for 1.93%. The surveillance results according to visual observation showed that the infestation rate of adult and nymph cockroaches was 3.63%, with 3.07% for B. germanica and 1.28% for P. americana. Farmers' markets and restaurants had high cockroach infestation rates. The cockroach infestation rate was high in South China and low in North China. The cockroach infestation rate measured by the sticky trap method was 1.45 times that by visual observation. Conclusion The national cockroach surveillance results in 2019 are conducive to the targeted cockroach control of key species in key habitats and areas, and at key times.

Objective To analyze the Aedes surveillance data of 23 project provinces (autonomous regions and municipalities directly under the central government) in China, 2019, and to provide scientific evidence for the prevention and control of Aedes-borne diseases such as dengue. Methods The surveillance data of larval and adult Aedes mosquitoes from the surveillance sites of the 23 regions were analyzed using SPSS 18.0 software for a preliminary assessment of the risk of dengue transmission. Results In China, 2019, the mean Breteau index (BI) of Aedes mosquitoes was 3.56, and the mean mosquito ovitrap index (MOI) was 4.89. During the key months of the surveillance periods, the mean BI exceeded 10 in Zhejiang, Hainan, and Fujian provinces, and exceeded 5 in some surveillance points of Yunnan province. MOI was over 5 in Guangdong province and Guangxi Zhuang autonomous region during the key months of the surveillance periods. In Jiangxi, Anhui, Hunan, Henan, Sichuan, and Hubei provinces and Chongqing municipality, BI exceeded 5 in most months of the surveillance periods; MOI exceeded 5 in Hunan province from June to August and in Guizhou province from July to September, reaching the spreading risk of dengue. During the surveillance periods, BI exceeded 10 in Hebei province, and exceeded 5 in Shaanxi province from July to August and in Shandong province from August to September. The density of adult mosquitoes (net trap index) was more than 2 mosquitoes/net·hour in Fujian and Jiangsu provinces and Guangxi autonomous region during most months of the surveillance periods, in Hubei province from June to July, and in Shaanxi and Sichuan provinces during September. Conclusion In 2019, the densities of Aedes mosquitoes in most project provinces (autonomous regions and municipalities directly under the central government) of China exceed the transmission or outbreak threshold of dengue, indicating a high risk of local transmission and outbreak of dengue. Aedes surveillance and risk assessment should be strengthened continuously to ensure sustainable and precise control of Aedes mosquitoes and Aedes-borne diseases.

Objective To investigate the species, composition, density, distribution, and seasonal fluctuation of mosquitoes in China, 2019, and to provide a scientific basis for the prevention and control of mosquito-borne diseases. Methods The mosquito vector surveillance data of 88 surveillance sites in 30 provinces (autonomous regions and municipalities directly under the central government) of China in 2019 were collected. The light trapping and human-baited double net trapping methods were employed to monitor adult mosquitoes, and the Breteau index (BI), scoop capture, and route methods were adopted to monitor mosquito larvae. Adult mosquitoes were monitored twice a month, and mosquito larvae were monitored once a month. Excel 2013 software was used to analyze the mosquito vector surveillance data. Results The mean density of mosquitoes was 9.81 mosquitoes/lamp·night in China in 2019. Culex pipiens pallens/Cx. pipiens quinquefasciatus accounted for 57.73% of all captured mosquitoes, followed by Anopheles sinensis, Cx. tritaeniorhynchus, Aedes albopictus, and Ae. aegypti, which accounted for 20.27%, 12.22%, 2.29%, and 0.02%, respectively. The mosquito densities in Inner Mongolia, Hubei, Qinghai, Yunnan, and Hunan provinces were relatively high, being 22.60, 21.72, 17.14, 12.71, and 10.18 mosquitoes/lamp·night, respectively. The results of seasonal fluctuation by light trapping, human-baited double net trapping, scoop capture, and route methods all indicated that the peak period of mosquito activity was from June to September, and the highest peak was in July or August. The results of the Breteau index method indicated that the peak period of Aedes larvae was from April to September. The highest density of adult mosquitoes was in livestock sheds, being 36.29 mosquitoes/lamp·night, while the highest Breteau index of mosquito larvae was in waste tyre recycling factories, being 19.25 mosquitoes/lamp·night. Conclusion The dominant mosquito specie is Cx. pipiens/Cx. pipiens quinquefasciatus in China. It is recommended to implement prevention and control measures such as overwintering mosquito elimination and environment management from April each year in all provinces (autonomous regions and municipalities directly under the Central Government). In 2020, the main prevention and control measure is to pay more attention to timely cleaning of the mosquito breeding sites in residential areas, waste tyre recycling factories, and waste collection areas, so as to prevent and control mosquito-borne diseases from the origins.

Objective To analyze the national surveillance data of rodents in China, 2019, and to provide a basis for improving the quality of national rodent surveillance and formulating scientific control measures. Methods Eighty-nine prefecture-level cities were set up as surveillance sites in 30 provinces (autonomous regions and municipalities) and Xinjiang Production and Construction Corps. Rodents were captured once every two months in three habitats by night-trapping, night-cage and sticky board methods. The surveillance data of rodents were collected and sorted to analyze the species composition, distribution, and seasonal density fluctuation of rodents. Results A total of 4 317 rodents were captured in 2019, with a total density of 0.78 rodents/100 traps. Cage trapping had the highest density of captured rodents, followed by sticky trapping. Rattus norvegicus, Mus musculus, and R. tanezumi accounted for 47.30%, 27.89%, and 12.55% of the total rodents captured, respectively. The highest density of rodents was in rural residential areas among three habitats. The density of rodents first increased and then decreased all year round, and peaked in May. Conclusion The density, species composition, and seasonal fluctuation of rodents at national surveillance sites across China in 2019 show no significant differences from the results in 2005-2016. Local authorities should assess risks and formulate control strategies based on their surveillance results of previous years.

Objective To establish the mosquito vector surveillance capacity in Freetown, Sierra Leone, and to investigate local mosquito density, geographical distribution, population characteristics, and seasonal fluctuations. Methods A total of nine zones were selected as mosquito surveillance sites in the western urban and rural areas of Freetown, Sierra Leone, with at least one site in each of residential areas, general working institutions, hospitals, and livestock sheds, and mosquito trap lamps were used for surveillance. Each surveillance site had 2-4 mosquito trap lamps, which were fixed in an outdoor place protected from wind, rain, and light at about 1.5 meters above the ground. The mosquito trap lamps were placed at 1 hour before sunset and the net was collected at 1 hour after sunrise in the next morning. Then the collected mosquitoes were classified by morphological characteristics in the laboratory. Mosquito surveillance was conducted once a week from June 26, 2019 to December 31, 2019. Excel 2007 software was used for the statistical analysis of mosquito vector surveillance data. Results A total of 3 012 mosquitoes were collected, among which Culex mosquitoes accounted for 84.86% and was the dominant mosquito genus in Freetown. Compared with the western urban areas, the western rural areas had significantly higher mean total mosquito density (5.01 mosquitoes/trap·night vs 3.87 mosquitoes/trap·night), mean Anopheles density (1.28 mosquitoes/trap·night vs 0.12 mosquitoes/trap·night), and composition ratio of Anopheles (1.14%-44.53% vs 0.72%-11.90%). Seasonal fluctuations of mosquito density showed that in Freetown, high mosquito density was observed during the alternate period of dry and rainy seasons in late June and early July and during the alternate period of rainy and dry seasons in late October and early November, and the lowest mosquito density was observed in late August. In addition, the seasonal fluctuation trend of Anopheles density was consistent with that of total mosquito density. A comparative analysis of different habitats showed that the livestock sheds with poor environmental sanitation and more mosquito breeding sites had a higher mosquito density (10.40 mosquitoes/trap·night), followed by residential areas (4.45 mosquitoes/trap·night) and general working institutions (2.80 mosquitoes/trap·night), and the hospitals with better environmental sanitation and fewer breeding sites had the lowest mosquito density (1.21 mosquitoes/trap·night). Conclusion The risk of mosquito bite and malaria infection in the western rural area is higher than that in the western urban area. The alternate periods from the dry season to the rainy season and from the rainy season to the dry season are important periods for the prevention and control of mosquito vectors and their infectious diseases (including malaria). Sierra Leone needs to further strengthen the management of mosquito breeding sites.

Objective To investigate the malaria infection rate among Chinese staffs of Chinese-funded institutions in Sierra Leone and train them to acquire comprehensive knowledge of malaria vector control. Methods Chinese-funded institutions selected their staffs to receive training on malaria vector control. Using the cluster sampling method, a questionnaire survey was conducted among all 134 trainees before the training course started. The trainer taught the knowledge of malaria vector control face to face using PPT (PowerPoint), and the trainees learned about the principal vector of malaria in Sierra Leone, Anopheles gambiae, and its characteristics and habits through the study of mosquito specimens. After the training, the questionnaire of malaria vector control knowledge was used again to evaluate the training effect. The results of questionnaire survey were analyzed statistically using the t test and chi-square test. Results The mean awareness score of mosquito vector control knowledge was 31.46±20.68 before training and 85.98±16.33 after training, with a significant improvement ( F=565.636, P<0.001). The investigation showed that the malaria infection rate average among trainees in the past year was 29.10%, significantly higher in outdoor workers than in indoor workers (37.40% vs 5.70%, χ ²=12.561, P<0.001). The analysis of correlation between trainees' pre-training scores and malaria infection rate showed that compared with the highly educated staffs, those with a lower education level had the lower mean score and a significantly higher malaria infection rate ( χ ²=6.152, P=0.046). The pre-training scores showed a negative correlation with the malaria infection rate. Conclusion In Sierra Leone, the training on mosquito vector control knowledge should be strengthened among the staff members of Chinese-funded institutions, especially those working outdoors and those with a lower education level. Training plans should be developed based on local mosquito vector surveillance data and malaria epidemic situation, and training on relevant mosquito vector control knowledge should be conducted regularly for the Chinese staffs abroad so that they can protect themselves from mosquito-borne diseases such as malaria.

Objective To investigate the current status of residents' awareness of dengue in Jinghong, Xishuangbanna Dai autonomous prefecture (Xishuangbanna prefecture), Yunnan province, China, and to provide a scientific basis for the establishment of accurate response mechanism and the sustainable control of dengue. Methods A representative grid was selected randomly from the grids with dengue prevention and control during the period of dengue outbreak in Jinghong in 2019. A questionnaire survey was conducted among the residents in the grid in a one-to-one question- and-answer manner. SPSS 20.0 statistical software was adopted for the statistical analysis. Results A total of 249 valid questionnaires were collected. The chi-square analysis revealed that urban residents paid more attention to dengue-related knowledge than rural residents ( χ ²=12.444, P=0.040). The education system staff and the highly educated ones paid more attention to the knowledge of mosquito control. Residents with different occupations, monthly average income levels, and levels of education chose different ways of seeking medical treatment if they were inadvertently infected with dengue. The highly educated ones, those high-income earners, and the education system staff were more inclined to go to the grade A tertiary hospitals. Urban residents held the view that there were more dengue infections around themselves than around rural residents. The highly educated population had a higher proportion of people who thought they had enough knowledge of dengue prevention and control than the less educated population. The results of unconditional logistic regression analysis demonstrated that residents with different ages, levels of education, and current places of residence showed different abilities to use new media to acquire knowledge about dengue prevention and control. Conclusion In Jinghong, Xishuangbanna prefecture, the elderly, the rural residents, the less educated people, and the low-income earners had a relatively low level of awareness of dengue. It is suggested that in future, the above-mentioned populations should be focused on in the establishment of local accurate response mechanism and the scientific prevention and control of dengue.

In order to further get the mosquito fauna in Qinghai province, China, a survey of mosquito larvae breeding sites was conducted in Ledu county, Qinghai province from August to September 2018. Specimens of mosquito larvae were collected, and were made into pinned specimens for morphological taxonomic identification after they were reared to adults. In this investigation, Culex ( Culex) vagans Wiedemann, 1828 was found among the mosquito specimens collected from the rural household water storage tanks and the river ditches in Ledu county. Culex vagans was firstly recorded in Qinghai province, China.

Objective To observe the effect of clarified lime water on Aedes albopictus at different stages of larval development in the laboratory and determine the effect of quicklime in the prevention and control of Ae. albopictus, and to provide basic data for the application of quicklime in the prevention and control of Ae. albopictus. Methods A certain number of Ae. albopictus at different developmental stages (eggs, 1 st to 4 th instar larvae, and pupae) were separately reared in clarified lime water, and the hatching rate, mortality rate, eclosion rate, and development time for each stage were recorded. Meanwhile, the development of Ae. albopictus in different feeding environments and different stages was analyzed and compared by taking the mosquitoes reared in overnight tap water as a control. Results The hatching rate of Ae. albopictus eggs in the experimental group was 82.22%, and that in the control group was 94.44%; the hatching rate of Ae. albopictus eggs was significantly lower in the experimental group than in the control group ( χ ²=6.523, P=0.011). According to the t-test, the hatching time of eggs was significantly longer in the experimental group than in the control group. The mortality rate of the 1st to 4th instar larvae was significantly higher in the experimental group than in the control group ( χ ²=4.624, 234.994, and 284.312, P=0.032, <0.003, and <0.003); particularly, the mortality rate of the 3rd and 4th instar larvae was significantly increased in the experimental group. There was no significant difference in eclosion rate between the experimental group and the control group ( χ ²=0.593, P=0.441). Conclusion Clarified lime water has a significant inhibitory effect on the development of Ae. albopictus, which increases with the age of mosquito larvae. The results imply that quicklime can be possibly used for the prevention and control of Ae. albopictus. The field control effect of quicklime on Ae. albopictus needs further verification.

Mosquitoes are important vectors and can cause serious disturbance to human life through blood sucking with stings and transmit a variety of pathogens, which poses a great threat to human health. Mosquitoes are widely distributed in different provinces, with different species of mosquitoes and viruses in different provinces. This article summarizes the major mosquito species and mosquito-borne viruses in Shandong province, in order to provide a reference for the prevention and control of mosquito-borne diseases.

Objective To analyze the correlation between density indices of Aedes larvae in key provinces of China, and to provide scientific evidence for the prevention and control of Aedes-borne diseases. Methods The Breteau index (BI), container index (CI), house index (HI), and mosquito ovitrap index (MOI) of Aedes larvae in Guangdong, Yunnan, and Zhejiang provinces of China from 2005 to 2017 were collected, and a database was established. A correlation analysis was performed using SPSS 13.0 software. Results In Guangdong province, there was a positive correlation between BI in 2016 and 2017 and MOI in the same period ( r=0.853 and 0.771, respectively, P<0.05). In Zhongshan, BI in 2016 and 2017 was positively correlated with MOI in the same period ( r=0.741 and 0.918, respectively, P<0.05), and there was a positive correlation between BI and CI, BI and HI, CI and HI, and HI and MOI in 2016 ( r=0.841, 0.990, 0.797, and 0.736, respectively, P<0.05). In Shantou, the four density indices in 2016 were all positively correlated with each other ( r=0.964, 0.982, 0.988, 0.772, 0.776, and 0.805, respectively, P<0.05). There was a positive correlation between BI and CI, BI and HI, and CI and HI in 2016 in Zhanjiang ( r=0.986, 0.998, and 0.980, respectively, P<0.05). In Yunnan province, there was a positive correlation between BI and CI, BI and HI, and CI and HI in 2014 and 2016 ( r=0.988, 0.978, and 0.973, respectively, P<0.05). There were a positive correlation between BI and CI, BI and HI, and CI and HI in 2016 and 2017 in Menghai county ( r=0.973, 0.982, 0.994, 0.954, 0.995, and 0.971, respectively, P<0.05). In Hekou county, BI was positively correlated with HI in 2016 ( r=1.000, P<0.05), and there was a positive correlation between BI and CI, BI and HI, and CI and HI in 2017 ( r=0.962, 0.945, and 0.961, respectively, P<0.05). In Longchuan county, there was a positive correlation between BI and HI in 2016 and 2017 ( r=1.000 and 0.974, respectively, P<0.05). During 2005-2010 in Yiwu, Zhejiang province, the four density indices of Aedes larvae were positively correlated with each other ( P<0.05), except between BI and CI in 2007 and between BI and CI, BI and HI, and CI and HI in 2008 ( P>0.05). In Fenghua, there was a positive correlation between BI and CI, BI and HI, and CI and HI in 2011 ( r=1.000, 0.994, and 0.993, respectively, P<0.05). In Cixi, there was a positive correlation between BI and CI, BI and HI, and CI and HI in 2011 ( r=0.980, 0.993, and 0.962, respectively, P<0.05). Conclusion The correlation between the density indices of Aedes larvae in different years in key provinces of China has spatial and temporal specificity, and the results can provide basic data for risk assessment and sustainable control of Aedes vectors and related diseases in different provinces of China.

Objective To investigate the fauna of mosquitoes in Tibet Autonomous Region, China. Methods From August to September, 2017, investigation and sampling, specimen preparation, and taxonomic identification were performed for mosquito larvae in various types of breeding sites in southeastern Tibet. Results A batch of specimens of the genus Aedes were collected in Motuo county, Linzhi. Among them, Aedes ( Diceromyia) whartoni Mattingly, 1965 was identified. The subgenus and species, which were first found in Tibet Autonomous Region and Yunnan province, were a new record of subgenus and species in China. This article briefly describes and reports the main morphological characteristics, geographical distribution, breeding environment, and male terminalia structure of the subgenus Diceromyia and the species whartoni of Aedes. Conclusion Up to now, 16 species of Aedes are known in Tibet.

Objective To investigate the species compositions of rodents and the chigger mites on their body surface and the infection rate of Orientia tsutsugamushi in rodents in Yongcheng, Henan province, China, and to provide a scientific basis for the prevention and control of scrub typhus in Yongcheng. Methods Rat traps were used to capture rodents and to collect ectoparasites from the body surface of rodents in different survey sites and different habitats in Yongcheng in October 2017. Nested PCR was used to detect nucleic acid of O. tsutsugamushi. The rodent density, chigger infestation rate, chigger index, and pathogen infection rate were calculated. Results A total of 110 rodents were captured with a capture rate of 12.21%. Apodemus agrarius accounted for 90.00%. A total of 1 249 chigger mites were collected from rodents. The chigger infestation rate and chigger index were relatively high in the forest along the riverbank, wetland, and mountain forest. Leptotrombidium scutellare (96.86%) was the dominant chigger mite species, which was mainly parasitic on the body surface of A. agrarius. The O. tsutsugamushi positive rate of rodent was 10.48%. Apodemus agrarius, Rattus norvegicus, and Mus musculus were detected O. tsutsugamushi positive with nPCR. Orientia tsutsugamushi in Yongcheng belonged to Kawasaki molecular type. Conclusion This study confirms that there are some epidemic foci of scrub typhus with host rodents in Yongcheng, which have the same hosts and vectors as the surrounding epidemic foci of scrub typhus.

Dengue virus can cause dengue fever, dengue hemorrhagic fever, and dengue shock syndrome, which is mainly endemic in tropical and subtropical regions. The epidemic area of Dengue virus has been increasing in recent years, which seriously endangers human health. This paper reviews the research progress in molecular biological characteristics and detection methods of Dengue virus.

Objective To investigate the infestation of bed bugs in China, and to provide a scientific basis for risk assessment and effective prevention and control of bed bugs. Methods The bed bug surveillance data were collected from the National vectors Surveillance in China in 2018. The occurrence of bed bug infestation was compared between different provinces or habitats. Results Bed bug surveillance was carried out in 13 provinces (autonomous regions, centrally administered municipalities) via field investigation and telephone survey. A total of 1 537 units were investigated on site, of which 11 had bed bug, infestation giving a positive infestation rate of 0.72%. A total of 17 332 standard rooms were investigated; among them, 31 (0.18%) had bed bugs. The habitats with the highest positive rates, in sequence, were dormitories in construction site, student dormitories, residential areas, nursing homes, and hotels. Conclusion Bed bugs are widely distributed in China, and the density of bed bugs in most areas was still at a relatively low level. The results of investigation indicated that construction site dormitories, residential areas, and student dormitories are the foci of bed bug infestation surveillance in the future.

Objective To investigate the common species, population density, and seasonal variation of cockroaches in residential areas and surroundings in China and the surveillance results of cockroaches based on the sticky trap method versus visual observation, and to provide a scientific basis for the prevention and control of cockroaches infestations. Methods The cockroach surveillance data were collected from national surveillance sites of the National Vectors Surveillance in China in 2018. The population density was compared between different species or cockroaches in different habitats or provinces, and its seasonal variation was analyzed. Results The cockroach infestation rate monitored by the sticky trap method was 6.70%, and among the predominant cockroaches, Blattella germanica was the predominant species and accounted for 94.81%, Periplaneta americana accounted for 2.11%, and other cockroaches accounted for 3.08%. The cockroach infestation rate was 3.58% according to visual observation, with 1.13% for Periplaneta and 2.71% for Blattella. Conclusion Blattella germanica is the dominant species in human habitats and surroundings in China. The cockroach infestation rate monitored by the sticky trap method is higher than that monitored by visual inspection, and visual inspection is more sensitive to the density surveillance of Periplaneta. The surveillance results suggest that surveillance and control of cockroaches should be strengthened in open markets and restaurants.

Objective To analyze the Aedes surveillance data of the National Vectors Surveillance in China of 23 provinces, autonomous regions, or municipalities directly under the central government in 2018, and to provide a scientific basis for sustainable control of Aedes-borne diseases in China. Methods The national Aedes surveillance data was statistically analyzed using SPSS 18.0 software. Results In 2018, the mean Breteau index (BI) of Aedes mosquitoes was 3.25, and the mean mosquito ovitrap index (MOI) was 5.19. In category I provinces with the high dengue risk, the mean BI of Hainan throughout the year, that of Zhejiang from the first half of April to the first half of November, that of Fujian from April to November (except the second half of April), that of Yunnan from the first half of July to the first half of October, and that of Guangxi from June to August and the second half of September were all higher than 5, indicating a risk of dengue transmission; the BI of 9 surveillance cities in Guangdong from March to November indicated a risk of dengue transmission; the mean MOI of Guangxi from the first half of May to the second half of September and that of Guangdong from the second half of May to the first half of October were all higher than 5, indicating a risk of dengue transmission. In category Ⅱ provinces with the medium dengue risk, the BI of Hubei and Sichuan from May to September, that of Shanghai from June to September, and that of Chongqing, Anhui, Jiangxi, Henan, and Hunan from May to October indicated a risk of dengue transmission; the BI of Jiangsu indicated no risk of dengue transmission during the study period. The MOI of Guizhou from June to September, that of Henan in July and September, and that of Hunan in July indicated a risk of dengue transmission. In category Ⅲ province with the low dengue risk, the BI of Shaanxi from July to September, that of Shandong from July to August, and that of Hebei from June to September were higher than 10, indicating a risk of dengue outbreak; the MOI of Beijing in August indicated a risk of dengue transmission. The adult density of Aedes in Guangxi from the second half of May to the second half of September (except the first half of July and the first half of September), that of Hainan from April to October, that of Ningbo, Zhejiang, from August to October, that of Hangzhou from July to November, that of Chongqing from May to September, that of Hubei and Jiangsu from June to September, that of Sichuan in July, and that of Shaanxi from July to August were higher than 2 mosquitoes per net per hour. Conclusion In 2018, the dengue transmission risk varies in different months in the three categories of provinces in China. Overall, the southern provinces have higher risk than the northern provinces, and the eastern coastal provinces have higher risk than the central and western provinces. It is suggested that Aedes surveillance and risk assessment should be strengthened in key provinces and cities to ensure sustainable control of Aedes for the prevention and control of Aedes-borne diseases in China.

Objective To analyze the mosquito surveillance data of the National Vectors Surveillance in China in the 31 provincial regions (provinces, autonomous regions, or municipalities directly under the central government) in 2018 and investigate the species composition, distribution, and seasonality of mosquito vectors, and to provide a basis for the risk analysis of mosquito-borne diseases and mosquito vector control program. Methods In 2018, the lamp trapping method, double mosquito net method, Breteau index (BI) method, scoop capture method, and route method were used to capture mosquitoes and record their numbers. The mosquito vector surveillance data throughout 2018 were collected from 90 national surveillance sites in the 31 provincial regions and analyzed by Excel 2013. Results In 2018, the dominant mosquito species in China's residential areas were Culex pipiens/Cx. pipiens quinquefasciatus, which accounted for 60.25% of all captured mosquitoes, followed by Cx. tritaeniorhynchus, Anopheles sinensis, Aedes albopictus, and Ae. aegypti, which accounted for 21.64%, 7.19%, 2.61%, and 0.23%, respectively. In all habitats, livestock sheds had the highest mosquito density, reaching 31.96 mosquitoes/lamp·night, followed by livestock farms and rural households, with 13.08 and 11.32 mosquitoes per lamp per night, respectively; the mosquito density was relatively low in parks, hospitals, and residential areas. The adult mosquito density began to increase during April to May, remained high during June to September, and declined in October; the density of mosquito larvae increased slightly earlier than that of adult mosquitoes. More Ae. albopictus was captured with the double mosquito net method than with other methods in all habitats, especially during June to September. Rural natural villages had the highest BI (22.04). Conclusion The mosquito surveillance data of the National Vectors Surveillance in China in 2018 showed a certain risk of mosquito-borne diseases such as dengue fever, Japanese encephalitis, and malaria in the residential areas of China. The mosquito density in livestock sheds was much higher than that in livestock farms, suggesting that intensive livestock production pattern may avoid mosquito infestation. The peak season of mosquitoes was from June to September, but larvae positive water bodies were found in early investigations, so mosquito vector control should be carried out early and continuously. Rural natural villages had a high mosquito density, and the risk of mosquito-borne diseases do exist. It is recommended to strengthen mosquito vector surveillance in order to provide accurate data for target mosquito control and provide a scientific basis for effective control of mosquito-borne diseases in China.

Objective To analyze larval Aedes density of 23 surveillance provinces in China from 2015 to 2017, and to provide scientific evidence for the risk assessment, early-warning, and control of Aedes-borne diseases. Methods Aedes larvae density data were collected from surveillance provinces of the dengue fever central government transfer payments project between 2015 and 2017, and were analyzed in different years and regions by SPSS 20.0 and Excel 2007 softwares. Results During the study period(2015-2017), the Breteau index(BI) in Hainan throughout the years, Zhejiang and Fujian during April to November, Guangxi during April to September, and Yunnan during June to October, were higher than 5, the Dengue virus transmission threshold, and reached dengue transmission risk level. The Mosq-ovitrap index(MOI) in Guangxi during April to October and Guangdong during March to November, were higher than 5, and showed the same trend as BI surveillance. The BI in Chongqing, Anhui, Jiangxi, Henan, Hubei, and Sichuan during most of surveillance months from May to October were higher than 5; Furthermore, BI in Henan and Hubei in most surveillance months were higher than 10, and reached dengue outbreak level. BI in Shanghai and Hunan during most surveillance months from May to September were higher than 5. BI in Hebei during June to September 2016 to 2017, and that in Shandong during July to September 2017 were higher than 5. BI during June to September 2016 and in May 2017 in Shaanxi were all greater than 5. Conclusion The dengue transmission risk varies in different provinces temporally. Overall, the category 1 provinces in southern parts of China including Guangdong, Yunnan, Guangxi, Hainan, Fujian, and Zhejiang have relatively high risk than other provinces. It is suggested that Aedes surveillance, risk assessment, early-warning, prevention and control should be strengthened in key provinces especially in south China for fostering the prevention and control of Aedes-borne diseases in the future.