ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
This paper reviews the taxonomic status of the genus Armigeres Theobald in the world,its phylogenetic status and research history. It also reviews the distribution of different species of the genus in different zoogeographic regions of the world and in China. At present,Armigeres includes 2 subgenera and 58 species worldwide. The Armigeres is mainly distributed in the Oriental Region,but a few species have spread to the Australian Region and to the Palearctic Region. Distribution of 48 species (82.7% of known species) is limited to the Oriental Region. Eight species (13.8% of known species) have distribution across both the Oriental and Australian Regions. Distribution of one species is limited to the Australian Region and one species is reported from both the Oriental and Palaearctic Regions. In China,there are 2 known subgenera and 19 reported species (32.76% of the global species). This work has established an information frame for further taxonomic research of the genus Armigeres in China.
Objective To clarify the interspecific phylogenetic relationship among the species of genus Anopheles subgenus Anopheles in China. Methods The phylogenetic relationship among 22 species (molecular forms) of subgenus Anopheles collected from China was reconstructed based on ribosomal DNA second internal transcribed spacer (rDNA-ITS2) sequences using neighbour joining, maximum parsimony, minimum evolution and maximum likelihood methods. Results The length range of rDNA-ITS2 was 340-1754 bp; the intraspecific genetic distances (p distance) were below 0.004, and the range of pairwise genetic distances among Anopheles mosquitoes was 0.009-0.420 (mean 0.224). All the reconstructed phylogeny trees showed that there were three clades, i.e., An. hyrcanus group, An. barbirostris group and An. lindesayi with An. maculipennis group and that the group clades were paraphyletic. There were four major clusters in An. hyrcanus group, and the interspecific relationship in each cluster was the same as the morphological taxonomy. However, the cluster positions of spLL1 and spLL2 were unstable. Conclusion The molecular phylogenetic tree reconstructed in this study objectively shows the interspecific phylogenetic relationship among the groups and species of genus Anopheles subgenus Anopheles in China. The rDNA-ITS2 sequences have sufficient contribution to the reconstruction of phylogeny of Anopheles species.
Objective To analyze the spatial and temporal distribution characteristics of dengue fever (DF) in Guangdong province, China during 2006-2011 and to provide a scientific basis for the prevention and control of dengue. Methods The annual incidence of DF in the county-level areas (counties or districts) of Guangdong province was determined during 2006-2011. The geographic pattern of DF incidence was examined by spatial autocorrelation analysis. Results The incidence rates of DF in the Pearl River Delta region and Han River Delta region were >4/105 and >2.5/105, respectively. Moran'sⅠ statistics of DF distribution were significant from 2006 to 2007 (P=0.005) and from 2009 to 2011 (P=0.001), but it was not significant from 2007 to 2008 (P=0.814). Conclusion The risk of DF is not randomly distributed among the county-level areas in Guangdong province, and the Pearl River Delta region and Han River Delta region are high-risk areas.
Objective To determine the complete genomic sequences of 3 Dengue 2 virus (DEN-2) strains isolated in Guangdong province, China and to investigate their genotypes and sources. Methods The complete genomic sequences of 3 DEN-2 strains (GD09/93, GD05/98, and GD19/2001) from Guangdong province were established by RT-PCR amplification. The phylogenetic tree of DEN-2 was constructed by Kimura method. Results The complete genomic sequences of 3 DEN-2 strains were 10 723 nucleotides (nt) in length and contained a single long open reading frame (ORF) of 10 173 nucleotides (97-10 269 nt), encoding 3391 amino acids. The ORF encoded structural and non-structural proteins, flanked by 5' and 3' non-coding regions. Comparing GD05/98 with GD09/93, GD05/98 with GD19/2001, and GD09/93 with GD19/2001, the nucleotide sequence homologies were 93.3%, 92.4%, and 97.6%, respectively, and the deduced amino acid sequence homologies were 96.7%, 96.5%, and 98.5%, respectively. Conclusion The DEN-2 strains are pathogenic in suckling mice. Compared with DEN-2-04 strain (nonpathogenic in suckling mice), there are 18 amino acid substitutions that confer changes in charge or polarity. The charge changes at PrM-134, NS2A-153, and NS4B-102 have a relatively strong impact on the antigenicity. GD05/98 strain falls within the groupⅡ comprising Thailand strains, while GD09/93 and GD19/2001 strains fall within the group Ⅳ comprising strains from Indonesia, Australian and Taiwan. There are different DEN genotypes in China, and one genotype of DEN-2 may be transmitted in different periods.
Objective To develop xMAP suspension arrays for simultaneous detection of tick-borne pathogens including forest encephalitis virus, Xinjiang hemorrhagic fever virus, spotted fever group rickettsiae, Babesia spp., Ehrlichieae, Francisella tularensis, Coxiella burneti, Borrelia burgdorferi, and Bartonella. Methods The 9 tick-borne pathogens were divided into two groups, and a multiplex PCR system was designed with up-primers labelled with anti-TAG and down-primers labelled with biotin. The PCR products were hybridized to the magnetic microspheres coupled with x-TAG. The conjugates were tested using the Bio-plex 100 system, and the 9 tick-borne pathogens were subjected to single and multiple detections and analyses. Results The mean fluorescence intensity three times higher than that of the background was judged as positive reaction. The results of single-plex and multiplex assays for the pathogen cultures demonstrated specific positive signals, without cross reaction, and the stability, sensitivity, and specificity of the method was good. Conclusion The liquid biochip technology platform with the beads coupled with x-TAG, which can simultaneously detect 9 tick-borne pathogens, has been successfully established. This platform holds promise for detection of tick-borne pathogens.
Objective To assess the risk of deltamethrin resistance development in Musca domestica and predict the rate of resistance development, and to provide a scientific basis for prolonging the service useful life of insecticides, protecting the effectiveness of existing insecticides, maximizing the potential of insecticides, and properly applying insecticides. Methods The resistant M. domestica strain for resistance risk assessment was obtained by lab resistance selection and bioassay. The resistance realized heritability (h2) was estimated using Tabashnik method, and then the rates of resistance development under different selection pressures were predicted. Results The resistance ratio was increased to 2197.55-fold in the deltamethrin-resistant M. domestica strain after 21 consecutive generations of lab selection. The h2 of M. domestica to deltamethrin was 0.1571, indicating a relatively high risk of resistance development. According to the general pattern of resistance development in M. domestica (the deltamethrin resistance development in M. domestica can be divided into three stages: the resistance development is very slow within the first seven generations, becomes fast from the 8th generation, and tends to level off in later generations). The h2 values in three resistance development stages were 0.1016 (F0-F7), 0.2140 (F8-F17), and 0.0250 (F18-F21). According to the h2 values in different stages, we predicted that 10-fold resistance increase required 7.2-15.9, 4.9-10.8, and 44.4-98.1 generations under different selection pressures (mortality rates: 50%, 60%, 70%, 80%, and 90%). Conclusion The risk of deltamethrin resistance development is relatively high among M. domestica, so attention should be paid to proper use of insecticides based on the situation of targeted pest.
Objective To investigate the resistance of Culex pipiens pallens to five commonly used chemical insecticides in Dongping Lake area of Shandong province, China and to provide a basis for proper and efficient chemical control of mosquitoes. Methods From 2010 to 2011, the WHO bioassay was used to determine the susceptibility of field populations of Cx. pipiens pallens to five insecticides, and the coefficients of synergism between insecticides were calculated. Results Among the field populations of Cx. pipiens pallens, the resistance ratios for cypermethrin, propoxur, deltamethrin, acetofenate, and DDVP were 106.40, 4.30, 110.75, 0.60, and 4.09, respectively, in 2010 and were 94.30, 2.70, 112.33, 0.61, and 2.91, respectively, in 2011. The coefficients of synergism between DDVP and acetofenate and between propoxur and acetofenate were 164.39-171.08 and 188.28-221.84, respectively. Conclusion Cx. pipiens pallens in Dongping Lake area of Shandong province shows different degrees of resistance to five commonly used chemical insecticides. Therefore, insecticide mixture, as well as joint use of insecticides and synergistic agents, should be employed to prevent or delay the emergence and development of insecticide resistance in mosquitoes.
Objective To compare the quality between the glass specimens of acaroid mites prepared with three mounting media. Methods Polyethylene lactic acid phenol medium, Berlese medium, and Hoyer's medium were prepared according to formulae, and their physical and chemical properties were compared. Sixty glass specimens of acaroid mites were prepared with each medium and were observed under a optical microscope after being oven-dried. The obtained data were analyzed by chi-square test. Results Polyethylene lactic acid phenol medium was light yellow liquid, with a density of 0.99 g/ml. Berlese medium was reddish brown, with a density of 1.12 g/ml. Hoyer's medium was slightly lighter than Berlese medium, with a density of 1.37 g/ml. The optical microscopy showed that the glass specimens of acaroid mites prepared with Hoyer's medium had high transparency and stretched mite bodies, with little yellowing and blackening at both sides of mite bodies; the specimens prepared with the other two media had relatively low quality. The chi-square test revealed significant differences between the three media (χ2=15.54, P<0.01), and the specimens prepared with Hoyer's medium had significantly higher quality than that prepared with polyethylene lactic acid phenol medium (χ2=7.50, P<0.01) and that prepared with Berlese medium (χ2=15.70, P<0.01). Conclusion Glass specimens of acaroid mites prepared with Hoyer's medium have the best quality under a optical microscope, providing a reference for the preparation of high-quality glass specimens of acaroid mites.
Objective To investigate the distribution of mosquitoes in Chenlu scenic spot of Tongchuan, Shaanxi province, China to provide guidance for mosquito control. Methods Lamp-baited trap and human-baited net trap were used for assessing the density of adult mosquitoes. The positive rate of water containers in the external environment of residential area was determined, and the container index, house index, and Breteau index were determined to assess the density of mosquito larvae. Results According to the data collected using lamp-baited trap, the mean density of adult mosquitoes was 0.0874 mosquito/lamp·hour; the density of adult mosquitoes was highest in July (0.2018 mosquito/lamp·hour) and in farm for tourism (0.1429 mosquito/lamp·hour), followed by residential area (0.1078 mosquito/lamp·hour). According to the data collected using human-baited net trap, the mean density of adult mosquitoes was 7.4419 mosquitoes/net·hour; the density of adult mosquitoes was highest in August (30.6000 mosquitoes/net·hour). In the residential area, the mean container index was 14.48%, and the container index was highest in August (21.87%); the house index and Breteau index of residential area were 35.88% and 76.08%, respectively. Conclusion There are plenty of breeding places for Aedes, especially various water containers, in the environment of Chenlu scenic spot, and the density of Aedes albopictus is the highest. Measures should be taken to remove accumulated water and control the density of Ae. albopictus.
Objective To investigate the community structure of rodents in different habitats of Ordos sandland. Methods From April to October 2008, the rodent communities in seven types of vegetation in Ordos sandland were investigated by night trapping method. Results The population density and community structure of rodents differed across various habitats. The alfalfa habitat had the most species of rodents (5 species) and the highest diversity index (1.3075). Only Phodopus roborovskii was caught in the habitat of Astragalus adsurgens. P. roborovskii was the dominant species in all habitats, accounting for 65.83% of all rodents, but its population dynamics were different between different habitats. Conclusion Planting different types of vegetation can change the habitat conditions in Ordos sandland, thus leading to changes in the community structure and population size of rodents. Attention should be paid to the interaction between rodents and habitats in the process of sandland use.
Objective To study the distribution pattern of rodents in Qinghai province, China. Methods The data on 45 species of rodents, belonging to 9 families and 2 orders, were retrieved. The Ward's method was used for cluster analysis of rodents in each physical geographical unit of Qinghai. Results The rodents in Qinghai were clustered into two groups. The rodents from Qiangtang Plateau and Guoluo Yushu Plateau were clustered into a new group at a distance coefficient of 0.13, and the rodents from mountains north to Qinghai Lake, mountainous unit of Huangnan, Huangshui Valley, Qaidam Basin, and Qilian Mountains in Qinghai were clustered into a new group at a distance coefficient of 0.21. Conclusion The clustering results show interrelation between rodents and environment in different geographical units.
Objective To investigate the strategy, method, and results of later disposal in the plague epidemic areas of Guangxi Zhuang Autonomous Region, China. Methods The data on later disposal in the plague epidemic areas of Guangxi Zhuang Autonomous Region during 2002-2012 were subjected to statistical analysis and evaluation by epidemiological and statistical methods. Results From 2002 to 2012, the number of plague cases in Guangxi Zhuang Autonomous Region dropped from 42 to 0, the detection rate of Yersinia pestis from 0.19% to 0, the positive rate of F1 antibody from 0.38% to 0, the flea-carrying rate from 68.00% to 4.64%, and the flea index from 1.15 to 0.06; the rat density was controlled under 5%. Conclusion The later disposal in plague epidemic areas has obviously controlled the epidemic situation of plague, so it is worth promoting in the plague epidemic areas.
Objective To investigate the changes and seasonal fluctuations in the species composition and densities of mosquitoes in Three Gorges Reservoir Area in Yichang, Hubei province, China. Methods Mosquitoes were captured by electric mosquito-catching trap at fixed times and places and were then identified and counted. Results In the early stage of the construction of Three Gorges Reservoir Area in Yichang, the dominant species of mosquitoes in human houses and livestock pens were Culex pipiens quinquefasciatus, Armigeres subalbatus, Cx. pipiens pallens, and Anopheles sinensis. The dominant species, however, has been Ar. subalbatus in human houses since 2005 and in livestock pens since 2007. The adult mosquito density was significantly lower in human houses than in livestock pens. The seasonal fluctuation in adult mosquito density was in a bimodal pattern, with density peaks in the first ten-days period of June and the first ten-days period of August. Conclusion With the environmental changes in the Three Gorges Reservoir Area in Yichang, the density and species composition of mosquitoes vary. Mosquito monitoring should be strengthened to provide the basis for decision-making basis for effective prevention and control of vector-borne diseases.
Objective To analyze the epidemiological characteristics of new Bunia virus infections among hosts and vectors in Zhoushan Island area and to provide scientific evidence for their prevention and control. Methods Case surveillance was performed in accordance with the Ministry of Health Prevention Guide. In places with positive cases, ticks were collected using cloth flag method or from the body of rodents. Murine-like animals were captured every 3-months, using rodent cages; they were identified, and then their liver, spleen, blood, and lung were collected under aseptic conditions; RNA was extracted and subjected to fluorescence quantitative PCR. Twenty-five serum samples of cattle, sheep, and other animals were collected. A database was created using EpiData 3.1, and statistical analysis was performed using Excel 2003. Results In Daishan county, Zhejiang province, China, from 2011 to 2012, 24 human cases of new Bunia virus infection (in 11 males and 13 females) were confirmed, including 2 deaths; the minimum age was 47 years, and the maximum age was 85 years; 70.83% of all cases were aged over 60 years. Four cases had a history of tick bite. These cases were sporadic, with one case of familial clustering of infection and one case of imported infection. A total of 111 rodents were captured in the field, and 251 ticks were collected by either cloth flag method or from the body of animals. New Bunia virus nucleic acid was detected in ticks. Two new Bunia virus strains were isolated from the blood of two human cases; the S genes of virus strains had a high degree of homology, but with some difference from those of new Bunia viruses from six other provinces in China. Conclusion In recent years, there have been many cases of severe fever with thrombocytopenia syndrome in Daishan county, and new Bunia virus was detected in ticks. Thus, measures should be taken to enhance the study and surveillance of this disease.
Objective To observe the larvicidal activities of transgenic cyanobacteria with CryIVD gene of Bacillus thuringiensis subsp. israelensis against different larval instars of Culex pipiens pallens. Methods Transgenic cyanobacteria with CryIVD gene of Bacillus thuringiensis subsp. israelensis were cultured in large numbers and were then dried and stored. The larvicidal activities of transgenic cyanobacteria stored for different periods were determined against different larval instars of Cx. pipiens pallens.Results The dried and stored transgenic cyanobacteria demonstrated a high toxicity to Cx. pipiens pallens larvae, and the longer the dried ones were stored, the lower their toxicity was. Compared with fresh ones, the stored transgenic cyanobacteria had slightly decreased larvicidal activity. They killed over 50% of larvae of different instars in 48 hours at concentration of 105 cells/ml. At a concentration of 106 cells/ml, transgenic cyanobacteria stored for one year, two years, and three years showed similar larvicidal activities, resulting in no significant differences in mortality rate of Cx. pipiens pallens larvae (F=9.32, P>0.01), but there was significant difference in the mortality rate when comparison was made between the transgenic cyanobacteria stored for one year and three years at a concentration of 105 cells/ml (F=101.21, P<0.01). Conclusion The cryIVD gene of Bacillus thuringiensis subsp. israelensis and larvicidal activity of stored transgenic cyanobacteria remain stable, and the stored transgenic cyanobacteria provide a convenient way for use in the field.
Objective To investigate the species and densities of house rats and their fleas and to analyze the risk factors for plague prevalence in Xuanwei, Yunnan province, China. Methods According to the Plague Surveillance Guidelines in Yunnan Province the densities of house rats and flea-carrying rates were monitored in the town-level areas (villages, towns, or subdistricts) of Xuanwei from 1999 to 2012. The surveillance results were analyzed. Results Results During 1999-2012, a total of 1757 house rats were captured, with a mean density of 5.98% capture rate (peak level 11.36%). The dominant species were Rattus norvegicus (51.05%) and R. tanezumi (37.05%). The mean density of R. tanezumi was 2.22%, higher than the national standard (1%). The mean flea-carrying rate was 33.18%, and the total flea index was 0.84. No Xenopsylla cheopis was found. The dominant flea was Monopsyllus anisus (66.46%). A total of 1560 rodent serum samples were collected, and indirect hemagglutination assay was performed to detect F1 antibody. No positive samples were found. Conclusion No plague infection was found among rats in Xuanwei, but there is possibility of plague outbreak, noting the eco-epidemiological situation in the area.
Objective To investigate the susceptibility of Blattella germanica to five commonly used insecticides, beta-cypermethrin, chlorpyrifos, acephate, propoxur, and deltamethrin, in Fengtai district of Beijing, China, and to provide a scientific basis for proper use of insecticides. Methods A large number of adult B. germanica individuals were collected in a farmer's market in Fengtai district to obtain the first filial generation for testing in the laboratory. The insecticide film contact method, as recommended by the WHO, was used to determine the susceptibility of B. germanica to commonly used insecticides, and the median knockdown time (KT50) and corresponding 95% confidence interval (95%CI), knockdown rate, and mortality of B. germanica were used for estimating the resistance levels to commonly used insecticides. Results The mean resistance coefficients (R/S) of B. germanica to beta-cypermethrin, chlorpyrifos, acephate, propoxur, and deltamethrin were 7.91, 2.06, 2.79, 4.56, and 30.52, respectively, and the five commonly used insecticides had the rates of decrease in lethal effect within 24 hours at 100%, 13.33%, 20.00%, 73.33%, and 90.00%, respectively. Conclusion B. germanica in Fengtai district of Beijing have developed high resistance to deltamethrin and beta-cypermethrin, but its resistance to organophosphorus and carbamate insecticides such as chlorpyrifos and propoxur is relatively low, which may be due to the differences in the frequency and way of insecticide use.
Objective To investigate the species of Ixodidae in Hainan province, China. Methods Ixodidae ticks were picked from the bodies of hosts and taxonomic identification was conducted. Results Twelve species, representing 5 genera of ixodid ticks were collected. Haemaphysalis longicornis was a new record species of ixodids in Hainan province. Conclusion Further investigation of Ixodidae should be carried out in order to provide a scientific basis for the prevention and control of tick-borne disease.
This paper reports and describes a new species of the genus Atrichopogon Kieffer that was found in the Huainan area, China, i.e., Atrichopogon coma Song, Wang et Yu, sp. nov. The type specimen of this species is deposited in the Collections of Medical Entomology, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences.
Objective To investigate the distribution of disease vectors in Shijiazhuang, China and to provide a basis for their control and prevention of infectious diseases. Methods An investigation was carried out on disease vectors in Shijiazhuang, China. The vectors were collected by local residents. Results A total of 141 species of vectors, including rats, mosquitoes, flies, cockroaches, ticks, fleas, lice, and bedbugs were collected. Conclusion The basic background information on disease vectors in Shijiazhuang has been acquired, and the catalogue of main vectors in Shijiazhuang has been created.
Objective To monitor plague host animals, its vectors and plague epidemic and to provide a scientific basis for timely detection, prevention and control of plague epidemic. Methods Live rats were captured with cage traps in the daytime and were then taxonomically identified. The liver, spleen, and serum samples were collected from the rats for isolation of plague bacteria and detection of F1 antibody. The animals with unexplained death were searched for, and epidemic surveillance was conducted. Results TThe dominant species of house rats were Rattus norvegicus and R. tanezumi, and the dominant species of field rats was Apodemus agrarius. The mean rodent densities were 3.19% indoor and 2.82% outdoors. The mean flea-carrying rate of rodents was 1.89%, and the total flea index of rodents was 0.0493. The dominant species of rat fleas was Leptopsylla segnis. The samples from live rats were negative for F1 antibody and pathogens. Plague cases were not found althouth large numbers of animals with unexplained death. Conclusion The species compositions of plague hosts and vectors in historical epidemic areas remain stable with low densities, and plague epidemic has not been found. However, plague surveillance should still be performed for timely detection of abnormal signals and prevention of human cases.
Objective To investigate the seasonal fluctuation in mosquito density in Liaoning province, China and to provide a scientific basis for developing mosquito control strategies. Methods Light traps were set at 100 monitoring points in 14 cities in Liaoning province to monitor mosquito densities in rural and urban areas. Results From 2010 to 2012, a total of 67 034 mosquitoes were captured, with a mean mosquito density of 8.12 mosquitoes/(lamp·h). Culex pipiens pallens and Aedes vexans were dominant species, accounting for 44.4% and 32.9% of all mosquitoes. The mosquito density was the highest in barns, followed by in peasant households, parks, hospitals and in residential areas. The mosquito density showed a marked seasonal fluctuation in Liaoning province, with peak mosquito activity in August and September and less mosquito activity in May, June, and October. Conclusion The basic information on mosquito species, their density and seasonal fluctuation has been acquired, laying the foundation for mosquito control and prevention of mosquito-borne diseases.
Objective To identify the species compositions and densities of vectors in Shenyang, China during 2008-2010 and to provide technical support for the prevention and control of vector-borne diseases. Methods Rodents, mosquitoes, flies, and cockroaches were monitored using traps set at night, mosquito lamps, cage traps, and glue traps, respectively, to determine their species and densities. Results From 2008 to 2010, the rodent densities were 0.31%, 0.18% and 0.16%, respectively, with the highest density found in rural areas, and the dominant species was Rattus norvegicus. The adult mosquito densities were 8.56, 10.52 and 20.14 mosquitoes per light trap hour, respectively, with the highest density found in livestock pens, and the dominant species were Culex pipiens pallens, Aedes vexans, Ae. dorsalis and Anopheles sinensis. The fly densities were 14.93, 10.31 and 7.51 flies per cage-day, respectively, with the highest density found in the external environments of restaurants, and the dominant species were Lucilia sericata, Muscina stabulans and Musca domestica. The densities of Blattella germanica were 1.41, 1.05 and 0.94 cockroaches per glue trap, respectively, and the infestation rates were 36.97%, 25.75% and 22.82%, respectively, with the highest density and infestation rate found in hospitals and farmer markets. Conclusion The species compositions and densities of main vectors in Shenyang have been generally identified through a 3-year surveillance.
Objective To investigate the invasions of bedbugs and other disease vectors on an entry ship and to evaluate the results of disinsection. Methods The bedbugs and other disease vectors on an entry ship from abroad were investigated by visual observation and the collected specimens were identified. The introduced bedbugs and other disease vectors on the ship were killed by either residual spray, space spray or slit spraying with 0.5% Malathion water solution. Poisonous baits for cockroaches were put in the cabins at the same time. The results of disinsection were assessed. Results More than 300 specimens of bedbugs were collected in crews cabins and considered Cimex hemipterus (Fabricius, 1803). The mean densities of bedbugs were 180 bedbugs per man-hour collection and 300 bedbugs per square meter. Seventeen other species of disease vectors, including cockroaches, mosquitoes and flies were also collected on board. The result of disinsection was found 100% after treatment. Conclusion It is recommended to enhance quarantine inspection on entry ships. For the entry ships invaded by bedbugs and other disease vectors, comprehensive insecticide application should be adopted according to the type of vectors and their habitats.
Objective To investigate the resistance of malaria vector Anopheles to five insecticides in Liaoning province, China and to provide a basis for prevention and control strategies. Methods The filter paper contact method for adult mosquitoes, as recommended by WHO, was used to measure the mortality of malaria vector Anopheles and its susceptibility to five insecticides. Results Malaria vector Anopheles had resistance to five insecticides in Donggang city of Dandong and Beizhen city of Jinzhou, and the lowest mortality was only 16.7%. In Dandong, Tieling, and Jinzhou, Anopheles mosquitoes also developed varying degrees of resistance to 4% DDT, 0.05% deltamethrin, and 0.05% beta-cypermethrin, with the highest mortality of 97.4%. The 0.1% propoxur had good lethal effect on malaria vector Anopheles in Zhen'an district of Dandong and Kaiyuan city of Tieling, and 0.75% permethrin had good lethal effect on Anopheles mosquitoes in the Zhen'an district, all leading to a mosquito mortality of 100%. Conclusion In some areas of Liaoning province, malaria vector Anopheles maintains high resistance to DDT, and it also has varying degrees of resistance to beta-cypermethrin and deltamethrin. Thus, it is necessary to properly use the insecticides for delaying the development of insecticide resistance. Malaria vector Anopheles is relatively sensitive to propoxur and permethrin, so the two can be applied as main insecticides for Anopheles control at present.
Objective To investigate the feasibility and application effect of powder trace method in outdoor surveillance of rodent density in urban communities. Methods The powder trace method and rodent trace method were used simultaneously to monitor the outdoor rodent densities in 10 communities of Huangshi, China, and the surveillance results were subjected to statistical analysis. Results The powder trace method showed that the valid powder rate was 89.11% and the positive rate of rodent traces was 6.41%. The rodent trace method showed that the path index was 20.08 places/km. The correlation analysis revealed no significant correlation between the surveillance results of the two methods (r=0.407, P=0.243). Conclusion The powder trace method can be applied for outdoor surveillance of rodent density in urban communities when the weather is favorable.
Objective With the changes in environment and climate in recent years, the dermatitis outbreaks, caused by poisonous eucleid caterpillars, has increased. This investigation aims to determine the cause of this disease and find out the risk factors and route of exposure. Methods A case study and an environmental survey were carried out among the villagers with symptoms, and the epidemiological characteristics of cases were described. A case-control study (2:1) was performed, and experts were invited to identify the species of caterpillars. Results The attack rate (AR) in the village was 71.70% (223/311), highest among villagers over 80 years of age and those under 9 years of age. The AR in the village was higher than those in other villages. In the village, the AR was higher in the northern part than in the southern part and higher in the western part than in the eastern part. The environmental survey showed that a large number of caterpillars bred on a Pterocarya stenoptera tree near the Furun River at the northwestern corner of the village, and the experts identified the caterpillars as poisonous eucleid caterpillars. The case-control study showed that the risk factors for dermatitis caused by poisonous eucleid caterpillars were walking past the tree (≥4 times/d) (OR=12.0, 95%CI:3.9-51.0), washing the body with river water (OR=10.0, 95%CI:1.5-448.0), washing vegetables and clothes with river water (OR=4.5, 95%CI:1.4-19.0), and swimming in the river (OR=6.6, 95%CI:1.5-62.0). Conclusion The outbreak of dermatitis was caused by poisonous eucleid caterpillars, whose poisonous hair might contact the human skin by moving with wind or contaminating water.
German cockroach (Blattella germanica), the dominant species of cockroaches in China, has an important role in research due to its significance and harmfulness in medicine and economics and being a preponderant research model for many scientific problems. Functional gene research has been the basis for biological research in the post-genome era. RNA interference (RNAi) is a post-transcriptional gene (mRNA) silencing where endogenous or exogenous double-strand RNA specifically and efficiently suppresses the expression of a functional gene at cellular and gross levels. In view of the research value of cockroaches and the technical advantage of RNAi, this article briefly reviews the molecular mechanism of RNAi, with an emphasis on the latest research on the functional genes of B. germanica.
