The disease burden of vector-borne diseases account for a high proportion of all categories of infectious diseases, and poses a serious public health challenge. In the new era, the unsustainability of source of infection, route of transmission, and susceptible population, that is "Three links" and natural and social factors, namely "Two factors" in the epidemic of vector-borne infectious diseases drive the outbreak and epidemic of these diseases mentioned above directly or indirectly. This causes the emerging and re-emerging, imported and indigenous risks and burdens of vector borne diseases, the "two doubles risks and burdens". The Global Vector Control Response (GVCR) 2017-2030, integrated vector management (IVM) based sustainable vector management (SVM), provides solutions for vector-borne diseases control all over the world, which needs to be implemented urgently by member states according to local conditions. This paper reviews the current epidemic situation of vector-borne diseases and the latest strategies of vector control in the world, for providing reference for scientific and accurate control of vector borne diseases in future.

Objective To investigate the mutations in the knockdown resistance ( kdr) gene of dengue vector Aedes albopictus in Haikou, China, as well as genotypes and their distribution in different areas, to analyze the influencing factors on insecticide resistance for scientific control of Ae. albopictus. Methods In June and July, 2018, the larvae and pupae of Ae. albopictus were collected from the urban and suburb areas of Haikou and reared to adults. The collected individuals were identified by morphology and were cryopreserved at -20℃ with anhydrous ethanol. DNA was extracted from a single mosquito, partial fragments of the voltage-gated sodium channel gene on nerve cell membrane were amplified by PCR, and sequencing was performed to analyze the mutations in the kdr gene. Results In the 94 Ae. albopictus mosquitoes in the east, south, west, north, and middle of Haikou, mutation was detected at the F1534 locus of the kdr gene. There were four alleles at the 1534 locus, namely, wild-type TTC/F (113/60.11%), mutant TCC/S (66/35.11%), mutant TCG/S (1/0.53%), and mutant TGC/C (8/4.26%); there were six genotypes, i.e., homozygous wild-type F/F (39/41.49%), wild/mutant heterozygote F/S (33/35.11%) and F/C (2/2.13%), homozygous mutant S/S (15/15.96%) and C/C (1/1.06%), and mutant heterozygote S/C (4/4.26%). The proportions of genotypes varied between populations. Conclusion The kdr mutation rate is high in Ae. albopictus in Haikou. Local mosquito resistance should be further monitored, so that insecticides are used appropriately.

Objective To investigate the prevalence of 6 rodent-borne pathogens, in some suburban areas of Beijing, China. Methods TaqMan fluorescent probe-based quantitative real-time PCR (qPCR) was used for laboratory evaluation. Plasmid standards were prepared and standard curves were plotted. Detection thresholds were determined according to the reevaluated data. From January to June, 2017, the trap-at-night method was used to capture rodents in Chaoyang, Huairou, Mentougou, and Pinggu districts of Beijing, tissue samples were collected to extract nucleic acids, and qPCR was used to detect pathogens. Results A total of 160 rodents were captured, among which there were 59 Rattus norvegicus rodents, 69 Mus musculus rodents, 4 Apodemus peninsulae rodents, 25 Niviventer confucianus, and 3 Sorex spp.. The examination of spleen tissues showed that all rodents except Sorex were infected with Rickettsia typhi (8.1%), Orientia tsutsugamushi (1.3%), Anaplasma phagocytophilum (5.6%), Leptospira interrogans (18.7%), or Bartonella spp. (5.0%). No Francisella tularensis was detected in all rodents. There were co-infections with various pathogens including Leptospira interrogans and A. phagocytophilum in R. norvegicus and M. musculus. Conclusion Rodents in Beijing carry the pathogens of common, emerging and reemerging infectious diseases. The distribution investigation of animal hosts and vectors of these pathogens in these areas and prevention and treatment of related infectious diseases should be strengthened.

Objective To investigate the infection status and genotypes of Wolbachia in Nycteribiidae and Streblidae in Yunnan province, China. Methods From 2012 to 2017, Nycteribiidae and Streblidae were collected from bats in 9 spots in Yunnan province, i.e., Mangshi, Tengchong, Wanding, Menglian, Mengla, Xiangyun, Mojiang, Yongde county, and Baoshan city. The 16S rRNA and wsp genes of Wolbachia were amplified and sequenced by PCR. Phylogenetic analyses were performed on all the 16S rRNA and wsp genes. Results From 2012 to 2017, a total of 747 (48 batches) Nycteribiidae flies and 19 (6 batches) Streblidae flies were collected from the fur of bats in the 9 collection spots in Yunnan province. A total of 24 pairs of 16S rRNA and wsp genes of Wolbachia were identified in the 54 batches of samples. For the Nycteribiidae from the fur of bats in Yunnan province, Wolbachia infection was positive in 2 out of 6 batches of Phthiridium and 19 out of 37 batches of Eucampsipoda, but negative in any batch of Nycteribia (0/4) and Penicillidia (0/1). All 6 batches of Streblidae belonged to Brachytarsina, 3 out of which were positive for Wolbachia infection. Phylogenetic analysis of the 16S rRNA gene showed that the 24 Wolbachia strains shared the same evolutionary branch with one from termites (DQ837204), with a 98.80%-100% homology in nucleotide sequence. Phylogenetic analysis of the wsp gene revealed that the 24 Wolbachia strains belonged to the supergroups B and F. Conclusion Wolbachia has been widely distributed in Nycteribiidae and Streblidae in Yunnan province for a long time. Phylogenetic analysis of the wsp sequences suggests that all identified Wolbachia strains belong to the supergroups B and F.

Objective To analyze the effects of climate factors and mosquito density on dengue epidemic in Foshan, Guangzhou, Shantou, Shenzhen, and Zhuhai in Guangdong province, China. Methods Dengue surveillance data were obtained from the China National Notifiable Infectious Diseases Reporting System. Aedes density data were collected from the Dengue Vector Aedes Surveillance System. A generalized additive model was used to analyze dengue and Aedes density surveillance data from 2005 to 2015. Results The model results indicated that dengue fever showed a significant positive self-regulation effect (F_{1.96, 10.84}=6 588.650,P<0.01). Mosquito density was significantly positively associated with dengue incidence (F_{2.98, 10.84}=21.810,P<0.01). Mean maximum temperature of lag time 0 month showed a significantly positive nonlinear association with dengue incidence (F_{1.91, 10.84}=215.570,P<0.01). Days with precipitation of the previous month exhibited a significantly n-shape effect on dengue incidence (F_{2.99, 10.84}=101.590,P<0.01), which is positively associated with dengue incidence as days with precipitation was below 15 days, but negatively associated above the threshold. Conclusion Temperature and precipitation regulate the risk of dengue epidemic in Guangdong province. They affect the epidemic and outbreak of dengue fever mainly via changing mosquito population density and population dynamics. Overall, dengue incidence significantly increases with the changes in climate.

Objective To investigate the prevalence of wild rodent plague and commensal rodent infection in Jianchuan county, Yunnan province, China, and to analyze its risk to the population. Methods The host animals, vectors, and indicative animals of the plague among rodents in Jianchuan county in 2017 were investigated. Serological and bacteriological tests related to the plague were carried out on the collected specimens. The χ ² test was used to analyze the differences in the distribution of rodents and their parasitic fleas. Results (1) A total of 221 rodents were captured. The densities of indoor and outdoor rodents were 7.00% and 24.66%, respectively, with a significant difference ( χ ²=73.730, P=0.000). (2) Rattus tanezumi and R. norvegicus were the dominant indoor species; Eothenomys miletus and Apodemus chevrieri were the dominant outdoor species. There was a significant difference in the distribution of species between indoor and outdoor rodents ( χ ²=160.005, P=0.000). (3) Apodemus chevrieri was infected with 190 fleas; E. miletus was infected with 85 fleas; R. tanezumi was infected with 43 fleas; R. norvegicus was infected with 9 fleas. (4) The major flea species on A. chevrieri was Frontopsylla spadix; the major flea species on E. miletus was Ctenophthalmus quadrarus; the major flea species on both R. tanezumi and R. norvegicus were F. spadix. There was a significant difference in the major flea species between the four species of rodents ( χ ²=244.272, P=0.000). (5) One strain of Yersinia pestis each was isolated from the naturally dead R. tanezumi and the F. spadix on it, as well as Neopsylla specialis specialis on a living rodent. Conclusion The density of rodents and flea index were high in the wild plague foci of Jianchuan county. Frontopsylla spadix was the dominant species of parasitic fleas on both wild rodents and indoor rodents. The plague epidemic in this area was of high risk based on the assessment.

Objective To investigate the etiological characteristics and epidemiological significance of Yersinia pestis strains in Haibei Tibetan Autonomous Prefecture, Qinghai province, and to provide a scientific basis for the prevention and control of plague in this area. Methods Carbohydrate fermentation test, virulence factor detection, virulence determination, plasmid analysis, and different region (DFR) analysis were performed on a total of 104 Y. pestis strains isolated from Qilian, Menyuan, Haiyan, and Gangcha in Haibei Tibetan Autonomous Prefecture from 1956 to 2011. Results According to the biochemical typing, 73 of the 104 strains tested were classified as the Qinghai-Tibet Plateau ecotype, 25 as the Qilian Mountain ecotype, and 6 as the ecotypes different from those in the natural plague foci of Qinghai province. Plasmids with molecular weights of 6×10 ⁶, 45×10 ⁶, and 52×10 ⁶ were found in all of the strains. Seventy-seven (74.04%) of the 104 strains contained four virulence factors, and 98.51% (66/67) were velogenic strains. According to the DFR analysis, six genomovars were found:genomovar 8 (75 strains), genomovar 44 (20 strains), genomovar 5 (6 strains), genomovar 6 (1 strain), genomovar 7 (1 strain), and genomovar 11 (1 strain). Conclusion The Y. pestis strains isolated in Haibei Tibetan Autonomous Prefecture, Qinghai province have the specific characteristics of Y. pestis strains in Qinghai-Tibet plateau, with complex ecotypes and strong virulence. Monitoring, prevention, and control of plague, as well as dissemination of relative knowledge, should be strengthened in this area.

Objective To investigate the genotypes and genetic characteristics of Yersinia pestis strains isolated from Kangbao county in Hebei province, China in 2017. Methods The DNA of three Y. pestis strains isolated from Kangbao county in Hebei province in 2017 was extracted by boiling method and kit extraction method. According to the literature, the primers of 22 different regions (DFRs) and pMT1 were synthesized and the DFR sites were amplified by PCR. The genotype was analyzed after agarose gel electrophoresis. Results The DFRs in the three strains were DFR02-05, DFR08-11, DFR14, DFR19-22, and pMT1, but not DFR01, 06, 07, 12, 13, and 15-18. The genotype was G20 after alignment. Conclusion The genotype of Y. pestis isolated from the plague foci in Hebei province in 2017 is G20 and different from G17 isolated previously. The emergence of new genotype provides a basis for further study of the genetic characteristics and epidemiological characteristics of the strain.

Objective To study the association of the spatial distribution of Nosopsyllus laeviceps kuzenkovi with climate and environmental factors, to effectively predict the suitable distribution area for N. laeviceps kuzenkovi, and to provide a scientific basis for the prevention and control of animal plague. Methods From 2005 to 2014, the information on N. laeviceps kuzenkovi was collected from the survey of rat flea and nest flea in routine plague surveillance. The information source was the plague prevention and management information system, which was a subsystem of the Chinese Disease Prevention and Control System. Logistic regression was used to explore the climate and environmental factors for N. laeviceps kuzenkovi. The genetic algorithm for rule-set prediction (GARP) ecological niche model was used to predict the suitable distribution area for N. laeviceps kuzenkovi. The receiver operating characteristic (ROC) curve was used to validate the model. Results After screening, 21 climate and environmental factors were enrolled in the model. The area under ROC curve was 0.978, suggesting a strong prediction capability of the GARP model. The suitable distribution area for N. laeviceps kuzenkovi was located in the central part of Inner Mongolia Autonomous Region, northwest of Zhangjiakou in Hebei province, west of Yulin in Shaanxi province, north of Ningxia Hui Autonomous Region, northern of Shanxi province, and northeast of Gansu province. Conclusion The GARP ecological niche model is accurate and reliable in the prediction of the suitable distribution area for N. laeviceps kuzenkovi.

Objective To investigate the difference in the sequence of cytochrome C oxidase subunit I (COI) gene in Ixodes persulcatus from the Heilongjiang Suifenhe and Jilin Yanbian ports in China and foreign countries, and to provide a basis for the prevention and control of tick-borne diseases. Methods From June 2013 to August 2016, a total of 106 I. persulcatus ticks were captured at Heilongjiang Suifenhe and Jilin Yanbian ports, among which 31 were selected to extract genomic DNA. PCR was used for the amplification of the COI gene, and then a homology analysis was performed, a phylogenetic tree was established, and a genetic distance analysis was performed for two geographical populations of I. persulcatus. Results The sequence of the COI gene in I. persulcatus from Heilongjiang Suifenhe and Jilin Yanbian ports had a homology of 99%-100% with the sequence of the COI gene in I. persulcatus from Russia and the Altai region in the border of Kazakhstan. The genetic distance of I. persulcatus from Suifenhe and Yanbian ports was ≤ 0.003. Conclusion The sequence of the COI gene in I. persulcatus from Suifenhe and Yanbian ports in China is highly consistent with that from neighboring countries. There may exist a high level of gene exchange or migration.

Objective To analyze the expression level of transferrin gene in the susceptible population and resistant population of Culex pipiens quinquefasciatus. Methods RNA was extracted and was amplified by quantitative real-time PCR (qRT-PCR) to produce partial gene fragments of the target gene using the designed primers. After purification and sequencing, the sequence alignment was performed. The t test was used to statistically analyze the expression levels of transferrin gene in the susceptible population and resistant population of Cx. pipiens quinquefasciatus. Results The qRT-PCR analysis showed that the mean fluorescence quantification values of transferring gene in susceptible population and resistant population of Cx. pipiens quinquefasciatus were 15.21 and 18.41, respectively; the mean fluorescence quantification values of the internal reference gene in the two populations were 20.53 and 19.10, respectively. The expression level of transferrin gene in the resistant population of Cx. pipiens quinquefasciatus was reduced, and there was a significant difference in the expression level of transferrin gene between the two populations ( t=10.390, P<0.001). Conclusion The transferrin gene of Cx. pipiens quinquefasciatus can be used as a target gene for the detection and treatment of mosquito resistance.

Objective To investigate the mosquito species in the residential area around Erhai Lake in Dali, Yunnan province, China, and important features of ecological habit, and to provide a basis for developing local prevention and control measures for mosquito-borne diseases. Methods From September 2016 to August 2017, adult mosquitoes were collected by the mosquito lamp in the residential area around Erhai Lake, and larvae were collected by larvae fishing in different breeding sites during the rainy season from June to September. Morphological identification was performed for all the adult mosquitoes and stage Ⅳ larvae collected. Results A total of 29 667 adult mosquitoes and larvae were collected, with 37 species (subspecies) of 11 genera in 3 subfamilies, including 20 069 adult mosquitoes from 29 species of 7 genera in 2 subfamilies and 9 598 stage Ⅳ larvae from 27 species of 10 genera in 3 subfamilies. Culex tritaeniorhynchus was the dominant species (16 997/20 069, 84.68%); the larvae of Aedes albopictus and Armigeres subalbatus accounted for 26.87% (2 579/9 598) and 20.14% (1 933/9 598), respectively, of all larvae collected. Culex tritaeniorhynchus and Cx. pipiens quinquefasciatus were found during the whole year, with peak population densities in September; rice field, stream, and gutterway were the major breeding sites for the larvae of Cx. tritaeniorhynchus, and the water gathered in vase, basin, and pot was the major breeding site for the larvae of Cx. pipiens quinquefasciatus. The main breeding sites for Anopheles sinensis were rice field, stream, and gutterway, with a peak population density in September. The main breeding sites for Ae. albopictus were junked tire, abandoned wells, and landscape pond. Conclusion There are abundant mosquito species in the residential area around Erhai Lake. Culex tritaeniorhynchus, An. sinensis, and Ae. albopictus have various breeding sites, high population numbers, and a wide distribution. Local health authorities should strengthen the monitoring of mosquitoes for mosquito-borne diseases.

Objective To understand the seasonal variation in the population density of Aedes albopictus in Guangdong province, China, based on a standard surveillance method, and to provide a scientific basis for the early warning and prediction for Aedes-borne diseases. Methods From 2007 to 2017, the population density of Ae. albopictus in Guangdong province was monitored by Breteau index (BI), mosquito ovi trap index (MOI), and the mosquito light trap method. Results The Ae. albopictus larvae density surveillance in 9 506 102 houses resulted in a mean BI value of 2.94. The adult Ae. albopictus density surveillance using 1 428 078 effective mosquito ovitraps resulted in a mean MOI value of 4.98. The adult Ae. albopictus density surveillance using 82 019 effective mosquito light traps resulted in an overall Ae. albopictus density of 0.21 mosquito/lamp·night. Between-group comparison made by analysis of variance and the Bonferroni method showed that there was a significant difference in BI surveillance results between different environments ( F=69.158, P<0.01). However, there were no significant differences in MOI or mosquito light trap surveillance results between different environments ( F=1.642, P=0.174; F=1.973, P=0.081). According to the surveillance results by the three methods, the population density of Ae. albopictus was higher in summer and autumn than in winter and spring. Conclusion Aedes albopictus exists all the time of a year in Guangdong province. The population density of Ae. albopictus varies with year, and season. Therefore, the prevention and control of Ae. albopictus should be performed on a case-by-case basis. The sensitivity of a surveillance method varies with environment, suggesting that the selection of surveillance methods should depend on the surveillance environment.

Objective To compare the effectiveness of two vector surveillance methods, double mosquito net and BG-mosquito trap (BG-trap), for collecting mosquitoes on the spot of dengue fever, and to provide a basis for rational surveillance approaches. Methods From September to October, 2017, 160 residential areas were selected from 12 districts and counties of Hangzhou, Zhejiang province, China, which contained the core area, warning area, and surveillance area. The double mosquito net and BG-trap were both used for emergency surveillance of vector Aedes albopictus in residential areas and the surrounding environments. The interval between the two traps was longer than 100 m. The surveillance lasted for 30 min. The biting index (mosquitoes/hour) and mosquito index (mosquitoes/h) were calculated. One-way analysis of variance was used to analyze two mosquito trapping methods in different areas. The paired t test was used to compare the efficiency between the two methods. Results Both the double mosquito net and BG-trap were able to capture Ae. albopictus, 903 mosquitoes were captured by BG-trap trap and 456 by the double mosquito net method. BG-trap had the highest efficiency in the monitoring area, followed by the warning area and the core area ( F=9.951, P<0.05). There was no significant difference in the efficiency of the double mosquito net between different areas ( F=2.677, P=0.072). According to the results of paired t test, BG-trap had significantly higher efficiency than the double mosquito net in the core area, warning area, and all areas ( t=2.786, 2.351, 3.976, all P<0.05). Conclusion Both surveillance methods can be used to monitor the vector mosquito. The double mosquito net method is suitable for routine adult mosquito density surveillance, while BG-trap is more suitable for the emergency surveillance of mosquito-borne infectious diseases such as dengue fever.

Objective To investigate the resistance of Musca domestica to 6 commonly used insecticides in Beijing, China, in 2017, and to provide a scientific basis for rational use of insecticides. Methods Using sweep net or fly trap, the field population of M. domestica was sampled from 6 urban districts in Beijing (Dongcheng, Xicheng, Chaoyang, Haidian, Daxing, and Tongzhou) from August to October, 2017. The micro-drip method was used to determine the resistance of M. domestica to 6 commonly used insecticides, i.e., DDVP, chlorpyrifos, beta-cypermethrin, deltamethrin, lambda- cyhalothrin, and propoxur. Bioassay data were pooled, and probit analysis was conducted with POLO-Plus 2.0 software (LeOra Software Inc., Berkeley, CA) to calculate median lethal dose, slope, and their 95% confidence intervals. Results Varying degrees of resistance level of M. domestica to DDVP, chlorpyrifos, beta-cypermethrin, deltamethrin, lambda- cyhalothrin, and propoxur were observed in the 6 urban districts of Beijing (Dongcheng, Xicheng, Chaoyang, Haidian, Daxing, and Tongzhou). The order of insecticide resistance level, from high to low, was propoxur (>500), beta-cypermethrin (42.80-260.01), deltamethrin (14.53-52.15), DDVP (15.22-31.95), lambda-cyhalothrin (11.83-31.48), and chlorpyrifos (2.59-6.38). Conclusion Musca domestica in Beijing has developed resistance to 6 commonly used insecticides, especially to propoxur and beta-cypermethrin, which we suggest should be suspended. In order to prevent the increasing insecticide resistance of M. domestica, the remaining insecticides should be used rationally according to the results of insecticide resistance surveillance.

Objective To investigate the fauna of mosquitoes in Tibet Autonomous Region, China. Methods From August to September, 2017, investigation and sampling were performed for mosquito larvae in various types of breeding sites in southeastern Tibet. Results The genus of Heizmannia and three mosquito species of Hz. heterospina, Hz. reidi, and Hz. macdonaldi were found and captured for the first time in Tibet. They were the new records of the genera and species of local mosquitoes. This article described and reported the main morphological characteristics, distribution areas, breeding environment, and the structure diagram of male terminalia of the genus and species. Conclusion Heizmannia belongs to the Oriental fauna. The distribution of this genus and related species was found for the first time in southeastern Tibet, suggesting that the mosquitoes in southeastern Tibet with a low altitude belong to the Oriental fauna. In addition, the discovery of this genus and related species shows high diversity of mosquitoes in southeastern Tibet.

This paper reports 24 species of the genus Culicoides of hematophagous midges in Heihe, Heilongjiang province, China. A new species C. aihuiensis Wu, Jiao et Liu, sp. nov., was found. The new species is similar to C. heiheensis Li, Zhang et Liu, 2011. However, the male C. heiheensis has a pair of blunt bulge at the rear edge of the ninth tergum, a wide arch-shaped aedeagus, a petal-shaped middle part, connected parameres, and a pair of cornicults in the middle part, which are substantially different from the new species. The model specimen of the new species has been deposited in the Center for Disease Control and Prevention of Shenyang Command (Shenyang 110034, China).

Objective To establish the relative susceptibility baselines and diagnostic doses of the wild population of Haemaphysalis longicornis to common insecticides. Methods The wild population of H. longicornis without exposure to any pesticides was collected at Mount Wangwu in Henan, China from April to September in both 2013 and 2014. The residual film method was used to determine the susceptibility of adult H. longicornis to insecticides. DPS data processing software was used for probit analysis, and the toxicity regression equation was fitted to determine the median lethal dose and 99% lethal dose and then to calculate the diagnostic dose. Results The susceptibility baselines of H. longicornis to dichlorvos, temephos, bassa, permethrin, deltamethrin, and beta-cypermethrin were y=1.549 9+1.359 4 x, y=2.343 3+1.225 6 x, y=-6.850 7+5.213 9 x, y=0.866 1+1.571 1 x, y=0.411 6+2.277 8 x, and y=2.551 8+1.018 9 x, respectively; the diagnostic doses were 35.505 6, 10.764 7, 1.047 4, 25.872 9, 2.171 4, and 97.063 2 mg/L, respectively. Conclusion The relative susceptibility baselines of the wild population of H. longicornis to the six insecticides, as well as the diagnostic doses, have been established. The results can be used as a reference for monitoring the resistance of H. longicornis to pesticides.

Objective To compare different laboratory assays for identifying imported oval malaria in laboratories and to analyze the genotypes, and to avoid misdiagnosis and missed diagnosis of oval malaria. Methods Five cases of imported oval malaria returning from labor in Liaoning province, China were diagnosed by three methods:Giemsa staining microscopy, combined Biotech malaria RDT diagnostic kit, and nested PCR, and the results were compared. The 18S rRNA genes of Plasmodium falciparum in peripheral blood samples from the five cases were subjected to sequencing and homology analysis. Results The morphology of typical P. ovale was observed in all samples by Giemsa staining microscopy. The results of RDT detection and PCR detection of malaria were all positive. The 18S rRNA gene of Plasmodium falciparum was sequenced and a sequence of 800 bp in length was obtained. The homology of the 18S rRNA with that in oval malaria was up to 99% by GenBank alignment. Conclusion The results of nested PCR detection, rapid detection, and staining microscopy for oval malaria cases are consistent ( P. ovale). It is necessary to promptly strengthen the ability of microscopic examination for Plasmodium in the epidemic areas of malaria, and its combination with molecular biological detection technology can greatly reduce misdiagnosis and missed diagnosis of Plasmodium in laboratories.

Objective To analyze the epidemiological characteristics of the first indigenous dengue cases in Jiangxi province, China, to evaluate the efficacy of the prevention and control strategies, and to provide a basis for the prevention and control of dengue fever. Methods The information of the first indigenous dengue cases in Jiangxi province from September to October, 2017 was collected for descriptive analyses. Serum samples of the cases and Aedes albopictus larvae were collected for the detection of viral nucleic acids. Serum samples of healthy people in the core area were collected for IgG antibody detection. The results of mosquito prevention and elimination were evaluated by Breteau index (BI) and the double mosquito net method. Results The three dengue patients were all infected with dengue virus type Ⅱ. The time interval between onsets of fever was 17 days. None of them had travel history. A total of about 1 000 Ae. albopictus larvae samples were tested and turned out to be negative. In the core area, 3.00% of the healthy people were positive for dengue IgG. After the elimination of adult mosquitoes and breeding sources in the core area and the warning area, BI decreased from 22.43 at the first surveillance to 0.98 at the ninth surveillance; the mean biting index was controlled no higher than 2 mosquitoes/person·hour in the core area. Conclusion The outbreak is the first indigenous dengue infection in Jiangxi province. It has been effectively controlled by appropriate epidemic management.

Objective To analyze the epidemiological characteristics of scrub typhus in Baoshan, Yunnan province, China, and to provide a scientific basis for the prevention and control of scrub typhus in Baoshan. Methods The data of scrub typhus in Baoshan from 2006 to 2016 was collected from the National Information Reporting System of Infectious Diseases, and then analyzed using the descriptive epidemiological method and chi-square test. Results A total of 5 205 cases of scrub typhus were reported in Baoshan from 2006 and 2016, with a mean annual incidence rate of 18.82/100 000. The incidence rate of the disease increased by 65 times, from 0.57/100 000 in 2006 to 37.74/100 000 in 2016, showing a rising trend over the years ( χ ²=2 762.798, P=0.000). The peak incidence period of the year was from July to October, with the number of cases accounting for 88.90% of the total cases. The numbers of male and female patients accounted for 49.91% and 50.09% of the total number of cases, respectively; the mean annual incidence was 18.32/100 000 and 19.34/100 000, respectively. The cases of scrub typhus occurred in all age groups, with the majority aged 25 to 64 years old (55.62%); the highest incidence was among children aged 1 to 7 years old, followed by those aged 50 to 69 years old. The number of patients increased over the years, among whom farmers accounted for the largest percentage (64.92%) and showed an upward trend, followed by scattered children (19.27%) and students (11.39%). The incidence rate was highest in Longling county and lowest in Longyang district. There was a high incidence of scrub typhus in rural areas, with a fluctuating and increasing trend from 2006 to 2016. Conclusion The incidence of scrub typhus in Baoshan is relatively high, especially in the rural areas and among children, middle-aged or elderly population. Based on the epidemiology of scrub typhus, disease surveillance and health education should be enhanced in those areas and populations to reduce the incidence of the disease.

Objective To investigate the genotype and variation of hantavirus (HV) carried by host animals in the epidemic foci of hemorrhagic fever with renal syndrome (HFRS) in Shenyang, China. Methods The high-incidence areas of HFRS in Shenyang were selected. The host animals (rats) were captured simultaneously in residential areas and the field in the spring and autumn of 2017, and the rat lungs were collected. The HV antigen-positive rat lungs were detected by immunofluorescence assay (IFA), from which G2 segments were amplified by RT-PCR. Agarose gel electrophoresis was used to identify the genotype. Nucleotide sequencing of the amplified products was performed. Homology analysis was performed by DNAStar package. Results Seventeen HFRS-positive rat lung specimens were screened out by IFA. Gene segments of interest were amplified from 10 specimens by RT-PCR, all of which belonged to Seoul virus (SEO) type. The sequencing results of the amplified products indicated that, compared with domestic strains and some international standard strains, the nucleotide homology of the 10 SEO-type HV specimens was 99.3%-100%. The homology with the 80-39 strain (South Korea, 1996) was the highest (95.6%-96.2%). The deduced amino acid homology was 99.3%. Conclusion SEO was the major type of HV in HFRS epidemic foci in Shenyang. The G2 segment of HV carried by rats was highly homologous and had no obvious variation, and the genetic materials were relatively stable.

Objective To investigate the current status of vectors infestation in the urban area of Wuhan, China, in 2017, and to provide a scientific basis for vector control and National Hygienic City construction. Methods From June to September, 2017, a field investigation was performed to evaluate the current status of the vectors infestation in different types of units (places). The rodent trace method was used for the survey of rodents; the path method and the larva dip method were used for the survey of mosquitoes; visual observation was used for the survey of flies and cockroaches, and of the investigation of facilities for the prevention of rodents and flies. Results The total positive rate of indoor rodent density was 10.1%, the total failure rate of rodent-poof facilities was 17.2%, and the total path index of outdoor rodent density was 3.4. The total path index of water in small containers was 4.3, and the total dip index of large and medium waters was 5.8%. The density of mosquito larvae per positive dip was 5.5. The total positive rate of indoor adult flies was 7.3%; the total failure rate of fly-poof facilities was 14.0%; the total positive rate of fly breeding sites was 3.0%. The total invasion rate of indoor adult nymphae was 4.1%; the total positive rate of oothecae was 1.2%; the total positive rate of cockroach trace was 4.6%. Conclusion The current status of the vectors infestation in different types of units (places) of Wuhan obtained in this investigation provides background data for effective vector control and the consolidation of National Hygienic City in the future.

Objective To investigate the effect of a model of high-temperature steam equipment in killing indoor Blattella germanica and the possibility of high-temperature steam in killing common indoor insect vectors. Methods At room temperature, B. germanica were fastened and treated with high-temperature steam at different vertical heights, with an ejection time of 1 and 2 seconds, respectively. The insect-killing effect and the effective distance of the equipment were observed, and SPSS 16.0 software was used for the Pearson's chi-square test. Results High-temperature steam effectively killed B. germanica. When the ejection time was 1 second, there was a significant difference in death rate between the 0, 5, and 10 cm ejection distance groups (100%) and the 11, 12, and 13 cm ejection distance groups (30.0%)( χ ²=96.923, P=0.000), and the effective distance of high-temperature steam was 10 cm; when the ejection time was 2 seconds, there was also a significant difference in death rate between the 0, 5, 10, 11, and 12 cm ejection distance groups (99.3%) and the 13, 14, and 15 cm ejection distance groups (43.3%)( χ ²=103.935, P=0.000), and the effective distance of high-temperature steam was 12 cm. Conclusion Within the effective ejection distance, 100% of B. germanica can be killed by high- temperature steam, and the equipment may be used to kill insect vectors including fleas and bedbugs.

Objective To investigate the epidemiological features and etiology of imported chikungunya fever and related prevention and control measures, and to provide experience for future prevention and control of this disease. Methods An epidemiological investigation was performed for two patients with chikungunya fever imported from Bangladesh in August 2017 in Dongyang. Blood samples were collected and RT-PCR was used for nucleic acid detection of chikungunya virus. Results The blood samples of these two patients tested positive for nucleic acid of chikungunya virus. They both travelled to Bangladesh before the onset of this disease, and thus they were confirmed as imported cases from Bangladesh. Both patients were cured after symptomatic/supportive treatment. Conclusion Integrated prevention and control measures including isolation, mosquito control at epidemic spots, and clearance of breeding sites can effectively prevent local spread of this disease.

Japanese encephalitis (JE) is a zoonosis caused by JE virus. There are many vectors that can cause the transmission and epidemic of JE, which include more than 20 species of mosquitoes in China. In addition, midges are also important vectors that cannot be ignored. This article reports the types of JE vectors that have been found so far in China and the characteristics of transmission.

The mosquito-borne health education among specific sub-populations is an important approach to reduce the harm of mosquito-borne infectious diseases. It plays an important role in controlling mosquito-borne infectious diseases, reducing the number of mosquitoes and improving the quality of people's living environment. The research focus on the differences in mosquito-targeted health education among populations with various living environments, education levels, workspaces and occupations. In recent years, worldwide scholars have done such researches and have achieved some results. This paper gives a brief introduction to the research. progress in mosquito-targeted health education among specific sub-populations.

Objective To explore the health risk assessment for operators and residents using public health pesticides with developed resistance. Methods This paper refers to WHO's Generic risk assessment model for indoor residual spraying insecticides in 2018, attempts to conduct a preliminary health risk assessment based on 4 pesticidal active ingredients (beta-cypermethrin, alpha-cypermethrin, deltamethrin and permethrin), 3 types of formulation and 8 commercial products registered in China, and try to carry out their resistance health risk assessment. Results Most of risk levels to health are basically acceptable when adult Aedes albopictus, Ae. aegypti, and Culex pipiens pallens mosquitoes develop low levels of resistance to pyrethroids. Under high resistance ratios (50-fold for operators, 20-fold for residents) in these species, however, most risk levels to health are not acceptable. Conclusion The research and results are helpful to expand the study field of mosquito resistance and health risk assessment and analysis of influencing factors,so as to ensure the health and safety of operators and residents. It is necessary to strengthen resistance monitoring, improve pesticide usage, promote health risk assessment in integrated vector management.

Objective To investigate the composition and distribution of rodents, their trend of seasonal variation, and the density of rodents in different habitats in China, and to provide an scientific basis for the development of rodent control programs. Methods The rodent surveillance data of the National Vectors Surveillance in China in 2016 were collected and analyzed to investigate the composition of rodent species. The density of rodents was compared across species, habitats, and provinces. Seasonal variation of density was analyzed. Results Among the rodents captured in China in 2016, Rattus norvegicus had the highest density of 0.30 rodents/100 traps, followed by Mus musculus with a density of 0.09 rodents/100 traps. There was a fluctuation in the total density of rodents. Among the three habitats, rural areas had a significantly higher density of rodents than the other two habitats, and residential areas had the lowest density. Xinjiang Uygur Autonomous Region had the highest density of rodents (1.68 rodents/100 traps), followed by Guangdong province. The total density of rodents in China showed an approximately unimodal distribution, with higher densities from March to October. The dominant species R. norvegicus had a relatively low density in March and a significantly higher density than the other species in other months, and R. rattoides had a relatively low density throughout the year. Seasonal variation of rodents varied across species. Conclusion The national rodent surveillance in China in 2016 indicated there were slight fluctuations in the total rodent density throughout the year and seasonal variation of the rodent density varied across species and provinces. The above findings imply that different prevention and control measures should be taken based on surveillance and the local rodent borne diseases risks.

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 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 investigate common species, population densities, and seasonality of flies in human settlements and surrounding environments in China, and to provide a scientific basis for fly prevention and control. Methods The data of flies captured by the cage trapping method were collected from the National Vectors Surveillance in China in 2018. Excel 2016 software was used to analyze the constituent ratios. Population density was analyzed and compared between different species or flies in different habitats or provinces, and its seasonality was evaluated. Results Musca domestica, flesh flies, Lucilia sericata, and M. sorbens were found to have higher densities in 2018, which were 1.21, 0.50, 0.47, and 0.29 flies per cage, respectively. Farmers' markets had the highest fly density (5.61 flies per cage). The peaks of all flies captured and dominant species were both in June and July. Conclusion Musca domestica is the predominant species. The peaks of fly densities occured in June and July. Farmers' markets were the main habitat for the occurrence of flies. Therefore, preventive measures should be undertaken ahead of the peak period (i.e., April and May) to minimize the flies infestations.

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 investigate the density and seasonal variation of ticks captured from human settlement and surroundings in China, and to provide a basis for risk assessment and scientific prevention and control of ticks and tick-borne diseases. Methods The tick surveillance data in 2018 were collected from 53 surveillance sites of the National Vectors Surveillance in China. The dominant species of ticks were analyzed, and the density and seasonal variation of ticks were compared between different hosts, habitats, and provinces. Results Haemaphysalis longicornis was detected most frequently in 2018. Among the host animals, sheep and cattle had the highest tick index, and the tick index of urban pet dogs increased from 0.04 in 2017 to 0.15 in 2018. The tick density in surroundings of villages was higher than that in scenic areas. The highest index of on-host ticks was observed in July, and the highest density of questing ticks was observed in August; their secondary peaks were observed in April to May, and on-host ticks had an additional peak in September. Conclusion Haemaphysalis longicornis was the predominat species of ticks in human habitats and surroundings in China, sheep and cattle were dominant host animals, and surroundings of villages are the dominant habitat of ticks. There were 3 peaks in the curve of the index of on-host ticks and 2 peaks in the curve of the density of questing ticks. There was an increase in the tick index of urban pet dogs from 2017 to 2018. These results suggest that tick prevention and control should be strengthened for rural domestic animals and in surroundings of villages, as well as in early spring and the middle of the year. Tick infection in urban pets should not be neglected.

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 compare the epidemiological characteristics of indigenous dengue cases in the high-risk areas of Guangdong and Yunnan provinces, China. Methods The data of dengue cases from 2005 to 2017 were collected, which included the present address, sex, age, occupation, time of onset, time of diagnosis, and whether the cases were imported or not. Statistical analysis was performed using SPSS 20.0 and R 3.5.0. Results From 2005 to 2017, there were 44 676 and 3 676 indigenous dengue cases in the high-risk areas of Guangdong and Yunnan provinces, respectively. The two study regions were significantly different in the occupation, age, sex, and interval from onset to diagnosis for indigenous dengue cases ( χ ²=989.647, P=0.000; χ ²=98.666, P=0.000; χ ²=7.429, P=0.006; U=5.360, P=0.000). Besides, the indigenous dengue cases were mainly household and unemployed workers in the high-risk areas of Guangdong province and commercial service workers in Yunnan province. The indigenous dengue cases were widely distributed in all ages in the high-risk areas of Guangdong province, but concentrated in young adults in Yunnan province. The male proportion of dengue cases in the high-risk areas of Guangdong province was lower than that in Yunnan province. Conclusion The numbers of indigenous dengue cases in Guangdong and Yunnan provinces rose from 2005 to 2017, and there was a significant difference in their epidemiological characteristics between the two provinces.

Objective To detect the mutations in the knockdown resistance ( kdr) gene of the Aedes albopictus populations resistant and susceptible to permethrin, deltamethrin, and α-cypermethrin, and to elucidate the association between the resistance phenotypes and the kdr gene mutations. Methods From June to September, 2016, the Ae. albopictus populations in Ruili, Yunnan province, China, resistant to permethrin, deltamethrin, and α-cypermethrin and the Ae. albopictus populations, and the susceptible lab population of Jiangsu Ae. albopictus strain were collected, respectively, and their resistance phenotypes were detected by a bioassay. Individual genomic DNA was extracted. Three pairs of primers were sgnthetized for PCR amplification of partial gene fragments of voltage-gated sodium channel on the nerve cell membrane to detect the kdr gene mutations. The genotypes and their frequencies of the kdr gene of the resistant and susceptible populations were statistically analyzed. The chi-square test was used to analyze the association between the kdr gene mutations and the resistance phenotypes. Results A total of 500 kdr gene fragments were obtained, including 440 kdr gene fragments of Ae. albopictus resistant populations in Ruili and 60 kdr gene fragments of Ae. albopictus susceptible populations of Jiangsu strain. There was no mutation detected in the gene fragments from the susceptible populations. In Ae. albopictus resistant populations in Ruili, mutations were detected at the 1532, 1534, and 1763 sites. Both F1534S and I1532T mutations were detected in one sample. There were two alleles at the 1532 site, i.e., wild-type ATC/I (isoleucine) and mutant ACC/T (threonine), and their frequencies were 99.32% (292/294) and 0.68% (2/294), respectively; the frequencies of three genotypes-wild-type homozygous I/I, wild/mutant heterozygous I/T, and mutant homozygous T/T were 98.64% (145/147), 1.36% (2/147), and 0 (0/147), respectively. There were five alleles at the 1 534 site, i.e., wild-type TTC/F (phenylalanine), mutant TCC/S (serine), TCG/S (serine), TTG/L (leucine), and TGC/C (cysteine), and their frequencies were 59.53% (175/294), 29.93% (88/294), 0.68% (2/294), 2.72% (8/294), and 7.14% (21/294), respectively; the frequencies of six genotypes-wild-type homozygous F/F, wild-type/mutant heterozygous F/C, F/S, and F/L, mutant homozygous S/S, and mutant heterozygous C/S were 40.14% (59/147), 6.80% (10/147), 26.53% (39/147), 5.44% (8/147), 13.61% (20/147), and 7.48% (11/147), respectively. There were two alleles at the 1 763 site, i.e., wild-type GAC/D (aspartic acid) and mutant TAC/Y (tyrosine), their frequencies were 99.32% (292/294) and 0.68% (2/294), respectively; the frequencies of three genotypes-wild-type homozygous D/D, wild-type/mutant heterozygous D/Y, and mutant homozygous Y/Y were 98.64% (145/147), 1.36% (2/147), and 0 (0/147), respectively. Conclusion In the kdr gene of Ae. albopictus population resistant to pyrethroid insecticides in Ruili, mutations are detected at the 1532, 1534, and 1763 sites and no mutations are detected at the 989 and 1 014 sites. The mutations at the 1534 site are dominant and the mutations at the 1763 site are first discovered. Single mutation is dominant and only one sample contains both the F1534S and I1532T mutations. This study confirms that the kdr mechanism is one of the resistance mechanisms of Ae. albopictus populations against pyrethroid insecticides in Ruili.

Objective To investigate the optimal cryoanesthesia time for Aedes albopictus and Culex pipiens pallens and the survival status of them after cryoanesthesia, and to provide a scientific basis for anesthesia before mosquito bioassay. Methods A certain number of pupae of Ae. albopictus and Cx. pipiens pallens were put into different mosquito cages to obtain four cages each of emerged Ae. albopictus and Cx. pipiens pallens. At 2-3 days after emergence, they were stored in a freezer (-20±0.5)℃ for 5, 10, 15, and 30 s, respectively. They were taken out to observe the knock-down rate and first recovery time. And then they were given routine feeding in feeding rooms together with their respective control groups. Their survival status was observed and recorded. The median survival time and survival curve were compared between different freezing groups. Results The knock-down rates of Ae. albopictus after 5, 10, 15, and 30 s of freezing were all 100%. There was no significant difference in survival curve between the 5 s group and its control group ( χ ²=1.441, P=0.230), while the 10 s group and 15 s group had significantly shorter survival time compared with their respective control groups ( χ ²=24.407, P<0.01; χ ²=38.375, P<0.01). There were no recovering mosquitoes in the 30 s group. Five cages of Ae. albopictus from the 5 s group were put on ice floe for 3, 5, 10, 30, and 60 min, respectively. The first recovery time and daily survival status were observed. The first recovery time of Ae. albopictus in the 3 min group was 145 s, and there was no significant difference in survival curve between the female mosquitoes in this group and those in its control group ( χ ²=2.463, P=0.117); however, the female mosquitoes in the 5, 10, 30, and 60 min groups had significantly lower survival curves compared with their respective control groups ( χ ²=15.141, P<0.01; χ ²=22.518, P<0.01; χ ²=30.242, P<0.01; χ ²=43.672, P<0.01). The knock-down rates of Cx. pipiens pallens after 5, 10, 15, and 30 s of cryoanesthesia were 64.00%, 85.19%, 100%, and 100%, respectively. The first recovery times for the 15 s group and 30 s group were 3 s and 138 s, respectively. There was no significant difference in survival curve between the test groups and their control groups ( χ ²=7.225, P=0.124). Conclusion For Ae. albopictus, the optimal operation procedure for cryoanesthesia is 5 s freezing and 3 min placement on ice floe, while the optimal time for Cx. pipiens pallens is 30 s freezing.

Objective To provide a scientific basis for plague prevention and control in Guoluo Tibetan autonomous prefecture, Qinghai province, China (hereinafter referred to as Guoluo prefecture), by etiological analysis and determination of the antibiotic resistance-related genes of Yersinia pestis in that area. Methods A series of experiments including sugar alcohol fermentation test, toxicity test, virulence factor assay, plasmid analysis, and different region (DFR) genotyping were conducted on 13 Y. pestis strains isolated from Guoluo prefecture from 1978 to 2016. According to the gene sequences (aminoglycosides streptomycin-resistant strA and strB; beta-lactam antibiotics-resistant tem and ctx-m; and sulfonamides-resistant sul1 and sul2) published by the National Center for Biotechnology Information (U.S.), a pair of primers were designed for each gene. Polymerase chain reaction (PCR) amplification of the above 6 antibiotic resistance-related genes was carried out using the DNAs from the above 13 Y. pestis strains as templates, to detect whether they carried antibiotic resistance-related genes. Results According to the biochemical grouping, of the 13 test strains, 9 belonged to Qing-Tibet Plateau ecotype, and 4 belonged to Qilian Mountain ecotype. As shown by the results of the toxicity test, all the 13 strains were velogenic strains and 11 contained four Y. pestis-specific virulence factors. The test strains contained 2 types of plasmids with a molecular weight of 6×10 ⁶, 45×10 ⁶, and 65×10 ⁶ versus 6×10 ⁶, 45×10 ⁶, and 52×10 ⁶, respectively. The DFRs were divided into 4 genomovars, i.e., genomovar 5 (7 strains), genomovar 8 (4 strains), genomovar 36 (1 strain), and genomovar 01b (1 strain). In case of valid positive and negative controls, PCR assay of the antibiotic-resistant genes revealed a negative result for all the above 13 Y. pestis strains, and no strain was found to be resistant to streptomycin, beta-lactam antibiotics, or sulfonamides. Conclusion The strains isolated from Guoluo prefecture show the characteristics of Y. pestis from Qinghai-Tibet Plateau. Despite the fact that no antibiotic-resistant strains were found, which demonstrate high toxicity; therefore, it is necessary to enhance plague surveillance and health promotion to prevent plague spreading from animals to humans.

Objective To investigate the infection rate of ecto-and endoparasite of small mammals in Yunnan province, China. Methods From October 15 to December 16, 2016, small mammals were captured using the trap-day method in the northwestern and southern mountainous areas of Yunnan province. The captured small mammals were identified, followed by surface parasite examination and identification. Parasites were collected from diseased organs and intestines after dissection and then identified morphologically. SPSS 17.0 software was used for statistical analysis. Categorical data were expressed as frequency and percentage. The χ ² test was used to compare the infection rate between groups. Results A total of 766 small mammals, which belonged to 44 species, 18 genera, 8 families, and 5 orders, were captured, with a total density of 12.51%. The predominant species included Eothenomys eleusis, Apodemus draco, A. latronum, Anourosorex squamipes, and Rattus tanezumi. The infection rate of ectoparasites was 22.06%, including 21.67% fleas, 7.83% gamasid mites and 1.83% ticks, respectively. Among them, 27 species (61.36%) were flea-carrying small mammals, 24 species (54.54%) were gamasid mites, and 8 species (18.18%) were tick-carrying small mammals. The infection rate of endoparasites was 12.27%, with 6.66% for Hepatica capillariasis, 6.92% for tapeworms, and 0.26% for other nematodes. The rate of infection with ecto-and endoparasites was relatively high in the small mammals captured between 100 and 3 999 meters above sea level. Conclusion With high density and diverse species of small mammals in some mountainous areas of Yunnan province, the infection rate of ecto-and endoparasites is relatively high, resulting in risks of diseases transmitted from small mammals to humans.