ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective To develop a simple genotyping method for rapid differentiation of Yersinia pestis strains between Microtus and non-Microtus biotypes. Methods Specific primers were designed and applied to amplify the aspartase gene (aspA) through polymerase chain reaction (PCR) among 93 Y. pestis strains of diverse origins and biotypes. The PCR products were genotyped by restriction fragment length polymorphism (RFLP) analysis using the restriction enzyme Hpy CH4Ⅳ. Genetic polymorphisms of aspA were determined by direct DNA sequencing. Results Among the 93 test strains, the amplified products of aspA digested with Hpy CH4Ⅳ showed two genotypes: Microtus biotype strains (38) all had two RFLP bands in sizes of 101 and 126 bp, respectively; and non-Microtus biotype strains (58) consistently had one single RFLP band in size of 227 bp. Direct sequencing data confirmed that mutation at the recognition site for restriction enzyme led to differences in the RFLP banding patterns. Conclusion A new genotyping method (aspA-PCR-RFLP) was established for rapid differentiation of Y. pestis strains between Microtus biotype with low virulence and non-Microtus biotype with high virulence according to different RFLP banding patterns. The proposed method can be used for epidemiologic surveillance in plague foci.
Objective To determine the niche breadth, overlap, and inter-species correlations of mosquito species in five arid wetlands in North Xinjiang using ecological niche theory and relevant methods. Methods Mosquitoes were captured with carbon dioxide-baited light traps and were then classified and counted. Niche breadth and overlap were estimated with Shannon-Wiener's and Pianka's formulae, respectively. Hierarchical cluster analysis was performed with a matrix of the constituent ratio of individual species, and detrended correspondence analysis (DCA) was performed with the population size of each mosquito species in different wetland habitats. Results A total of 20 731 mosquitoes, belonging to 16 species in 5 genera, were captured in the five arid wetlands in North Xinjiang. Of these, Aedes dorsalis had the greatest niche breadth (0.8326), followed by Ae. vexans (0.6350), Ae. caspius (0.5954), and Anopheles messeae (0.5558). Regarding niche overlap index, there were 26 species (20.31%) with log-transformed values above 0.90 and 85 species (70.83%) with log-transformed values above 0.50. The five wetland habitats were classified into two major ecotypes by hierarchical cluster analysis. DCA ordination diagram showed the longest distance of Ae. sinkiangensis and Mansonia richiardii from other species among the mosquitoes tested. Conclusion The dominant mosquito species does not always has the greatest niche breadth. Similar mosquito population structure exists in the wetlands of Buergen River, the lower reach of Ertix River, and the lower reach of Yili River, as well as in the wetlands of Ebinur Lake and the estuary of Emin River. Species distribution of mosquitoes and their correlations with wetland habitats can be directly reflected by DCA ordination.
Objective To investigate the species composition and spatial distribution of small mammals in the mountainous region of southern Pu'er, Yunnan province, China. Methods During 2011 to 2012, a field survey was carried out at 19 villages and towns in four counties (districts) in southern Pu'er, i.e., Simao, Lancang, Menglian, and Jiangcheng. Small mammals were captured with small beast traps in an altitude range of 700-2000 m, covering six altitude gradient belts (Ⅰ-Ⅵ) and five major habitats (A-E). The richness of animal species, genera, and families was analyzed using the Shannon-Wiener diversity index. Results A total of 787 individual small mammals were captured and classified into 21 species of 11 genera, which belonged to 5 families of 3 orders, i.e., Rodentia, Insectivora, and Scandentia. Of these, the predominant species were Rattus tanezumi (30.24%), R. brunneusculus sladeni (19.95%), and Crocidura dracula dracula (10.04%). Geologically, the richness of small mammal genera and species presented a gradually increasing trend from east to west. In different vertical zones, there were 11 species (5 genera, 3 families) of small mammals in belt Ⅰ (700 m-), 14 species (10 genera, 4 families) in belt Ⅱ (900 m-), 17 species (9 genera, 5 families) in belt Ⅲ (1100 m-), 7 species (4 genera, 4 families) in belt Ⅳ (1300 m-), 13 species (7 genera, 5 families) in belt Ⅴ (1500 m-), and 12 species (7 genera, 4 families) in belt Ⅵ ( 1700 m-). By comparison, the richness of small mammal species, genera, and families was higher in belts Ⅱ and Ⅲ (around 1000 m) than in the other belts. In the major habitats, there were 13 species (8 genera, 4 families) of small mammals in type A broadleaf forest, 19 species (11 genera, 5 families) in type B farmland in broadleaf forest, 17 species (10 genera, 4 families) in type C mountainous farming area, 5 species (4 genera, 4 families) in type D shrubbery, and 9 species (6 genera, 3 families) in type E forest tea-growing area. Among different habitats, the richness of animal genera and species was the highest in the farmland in broadleaf forest. Conclusion The richness of small mammal genera and species presents a gradually increasing trend from east to west in the mountainous region of southern Pu'er, Yunnan. Among the 21 species of small mammals, R. tanezumi occurs as the predominant species with strong spatial distribution ability. There exist certain differences between different small mammal species in their selection and orientation of the environment as well as the ability of space resource utilization.
Objective To study the activity and efficacy of Bacillus thuringiensis serotype H-14 (B.t. H-14) against vector mosquitoes and the persistence of bacterial liquid preparation. Methods B.t. H-14 with high pathogenicity against mosquitoes was tested in the field sites. The densities of larval and adult mosquitoes were quantified by dippingand human-baited net trapping. The results were compared with the mosquito densities in an untreated control site to determine the field efficacy of B.t. H-14. The persistence of B. thuringiensis in different water bodies was observed in the laboratory. Results The relative population index (RPI) of vector mosquitoes was under 10 during peak periods, which indicated that B.t. H-14 lowered the populations of vector mosquitoes in natural habitats. The mosquito densities in the treated site remained at a relatively low level, with a larval density less than 50/dip and an adult density less than 20/hour. However, the density of mosquitoes in the untreated control site changed considerably with seasons, with a larval density more than 100/dip and an adult density up to 188/hour. In the laboratory, the activity of B.t. H-14 lasted 30 d. The larvicidal activity of B.t. H-14 was optimal in pure water; in polluted water, however, its activity reached the peakin one weekand then decreased gradually. Conclusion In the natural environment, B.t. H-14 can be used to control vector mosquitoes, and the concentration of bacterial liquid applied and the number of applications can be determined according to the mosquito population densities.
Objective To test the effect of a contraceptive compound (levonorgestrel-quinestrol, designated EP-1) on reproduction in field populations of Maximowicz's vole (Microtus maximowiczii). Methods In 2004, a field trial was conducted in a guinea grass plot in Baiyinxile pasture, Xilingol league, Inner Mongolia, China. EP-1 was applied at the end of April and the reproductive parameters of field voles were inspected in May to July by monthly line transect census and track surveys. Data were analyzed by independent-samples t test. Results EP-1 strongly inhibited reproduction in female voles in the field. In the EP-1 baited area, the uterine damage rate in adult female voles was 78.9% while their pregnancy rate dropped to 0% in early June. In early July, uterine damage rate remained at a similar high level (76.7%) as that in June; the corresponding pregnancy rate and mean litter size both rose rapidly, but still differed from those in the untreated control area significantly (P<0.05). In early August, the uterine damage rate in female voles fell to 30.0%. Conclusion EP-1 is a safe contraceptive compound for the effective control of reproduction in field M. maximowiczii populations. Its inhibitory effect lasts three months before the vole's reproduction starts to recover.
Objective To apply DNA barcoding in species identification of exotic vectors. Methods Morphology and DNA barcoding based identification was performed on two blowflies from Australia that were intercepted at the Shenwan port (Zhongshan, Guangdong) in September 2013. The identification results were confirmed with specialists in Australia and compared to data of a similar species, Calliphora augur. Results The two blowflies were identified as C. dubia, which represents exotic species in China based on sci-tech novelty search. Conclusion DNA barcoding is a strong supplementary tool for conventional taxonomy, which plays an important role in frontier health and quarantine inspection by timely identifying vector insects, reducing the spread of vector insects and the carried pathogens, and mitigating threats to public health.
Objective To evaluate the feasibility of DNA barcoding applied to the identification of flies in Fujian province, China, and to set up the nucleic acid sequence database for flies in Fujian. Methods Sixty-four fly specimens belonging to 19 species, 13 genera, and 4 families were collected from Fujian. Genomic DNA was extracted from the flies. Mitochondrial COⅠ gene was amplified by consensus primer PCR and sequenced. Sequence alignment and evolutionary divergence were performed, and a neighbor-joining phylogenetic tree was constructed based on these sequences. Results Intraspecific divergence ranged between 0-3.32%; interspecific divergence ranged between 5.26%-18.30%, except for Lucilia cuprina and Lucilia sericata, which had only 0.69% divergence from each other. The result of phylogenetic tree showed that sequences from the same species gathered closely with each other. The reliability of Bootstrap test was all above 96%. Conclusion DNA barcoding can be effectively used to identify some flies in Fujian province. It can be used as an efficient method supplementary to morphological identification.
Objective To investigate the influence of urbanization on the structure of rodent community in different habitats in the rural areas, and to provide a scientific support for carrying out rodent control. Methods Night trapping method was used to investigate rodent community structure in the rural areas after urbanization. Three hundred traps were set in each sample region. The distance between traps was 5 m and the interval between survey lines was above 50 m. Traps were placed at dawn and collected in dusk. Results The urban-rural encroaching zone became the most important habitat for rodents after urbanization. The number and biomass of house mice increased greatly, while the dominance of voles significantly decreased. In the urban-rural encroaching zone, Rattus norvegicus was the most predominant species and the most pestiferous rodent. In the farmland 500 m away from the town, R. losea was the most predominant rodent and R. norvegicus was the secondary; Bandicota indica, R. norvegicus, and R. losea were the most pestiferous rodents. In the farmland 2 km away from the town, R. losea was the most predominant rodent and Mus musculus was the secondary; R. losea and B. indica were the most pestiferous rodents. Conclusion Urbanization indirectly provides favorable conditions for rodent infestation, with some changes in farmland rodent community. Sustainable management should be strengthened in the face of such changes.
Objective To investigate the population densities and insecticide resistance level of Culex pipiens pallens in the lakeside area of Weishan Lake in Shandong province, China, before and after new countryside development. Methods Xicun village and Shizhuang village at the lakeside of Weishan Lake were used as countryside construction sample and control, respectively. The population density of mosquitoes was determined using the human-bated net trap, while insecticide resistance was evaluated with the use of WHO larva immersion method. Results After the new countryside development, the relative population index of Cx. pipiens pallens in Xicun village was 0.285, with a 71.50% decrease. The resistance to propoxur, DDVP, and acetofenate decreased by 88.52%, 93.50%, and 87.67%, respectively, while the resistance to cypermethrin and deltamethrin increased by 30.15% and 34.38%, respectively. Conclusion The new countryside development showed a positive impact on the control of Cx. pipiens pallens in the lakeside area of Weishan Lake in Shandong province. The use of pyrethroids should be reduced in Xicun village of Hanzhuang town.
Objective To investigate the epidemiological characteristics of the 2013 outbreak of dengue fever in Ruili of Yunnan province, China, and to promote management of dengue fever epidemics. Methods An investigation was conducted among all dengue fever cases. Serum samples of all cases were tested by NS1 antigen detection. The density of vector mosquitoes was determined by the Breteau index (BI). Results This outbreak of dengue fever lasted 104 days, and there were 232 confirmed cases, of whom 145 were locally infected cases, and 87 were imported cases from Myanmar. Cases were mainly distributed in the urban areas of Ruili (53.45%, 124/232). The male-to-female ratio was 1.23:1; the patients were mainly 20-49 years old, with the youngest 1 year old and the oldest 80 years old. Most of the patients were business people, farmers, housekeepers, and unemployed persons. Conclusion This was the first local outbreak of dengue fever in Ruili, which was caused by both Aedes albopictus and Ae. aegypti. With combined control of Aedes sp. mosquitoes and BI not higher than 5.0, the epidemic of dengue fever can be controlled.
Objective To investigate the effect of knockdown resistance mutations on the deltamethrin resistance of Anopheles sinensis. Methods The deltamethrin resistance of An. sinensis was determined by WHO cones test at six investigation sites in Hefei, China, from 2011 to 2012. Eighty An. sinensis specimens were randomly selected from each of the survival and death populations after the resistance test. DNA was extracted as templates for PCR amplification, and the IIS5-S6 transmembrane segments of voltage-gated sodium channel (VGSC) gene were cloned and sequenced. Chi-square test was used to compare mutation types between the two populations with SPSS software. Results Sequence analysis revealed two types of mutations (TTG to TTT and TTG to TGT) in both groups, with four combinations, i.e., heterozygous mutations TTG(T), TG(T)G(T), and TG(T)T and homozygous mutation (TTT). TGT mutation accounted for 36.9% of the survival population, higher than that of the death population (19.4%) (χ2=17.571, P<0.01), according to the comparison of mutation types (TTG, TTT, and TGT) between the two populations. Conclusion TGT mutation is more associated with deltamethrin resistance than TTT mutation.
Objective To investigate the resistance of Culex pipiens pallens to five commonly used insecticides in Hebei province, China. Methods The susceptibility of Cx. pipiens pallens larvae to commonly used insecticides was determined by WHO larval immersion method. Insecticide resistance was evaluated and compared based on median lethal concentration (LC50) and 95% confidence interval (95%CI). Results The LC50 values of beta-cypermethrin, permethrin, deltamethrin, fenobucarb, and DDVP for 11 field populations of Cx. pipiens pallens were 0.0008-0.1664, 0.0159-0.2280, 0.0006-0.0148, 0.0800-0.6138, and 0.1783-0.5000 μg/ml, respectively. As compared with the previously reported results (1991-1994), Cx. pipiens pallens showed increased resistance to permethrin and slightly decreased resistance to DDVP and deltamethrin. Conclusion The 11 field populations of Cx. pipiens pallens have developed different levels of insecticide resistance. The surveillance of insecticide resistance should be strengthened to provide guidance for the proper application of insecticides.
Objective To investigate the population density change of Culex pipiens pallens and its resistance to commonly used insecticides in Zhejiang province, China, and to provide a reference for mosquito control. Methods Light traps were used to determine the population density of Cx. pipiens pallens. The larva immersion method was used to determine the resistance of Cx. pipiens pallens to commonly used insecticides. Results The population density change of Cx. pipiens pallens showed a single-peak curve throughout the year, with a peak value in June, the highest average density among all habitats was found in rural households. Among different Cx. pipiens pallens populations, the resistance ratios to pyrethroids, organophosphorus, and carbamate were 1.31-20.43, 1.88-10.14, and 0.82-4.96, respectively. Most of field-collected mosquitoes showed resistance to pyrethroids at all sampling sites. Conclusion June is a key month of mosquito control in Zhejiang province, since the peak population density of adult Cx. pipiens pallens appears in June. Considering the prevalence of pyrethroids resistance among mosquitoes, comprehensive mosquito control should be promoted to delay the development of resistance to insecticides.
Objective To investigate the levels of resistance and the resistance stability of Blattella germanica to five commonly used insecticides, i.e., beta-cypermethrin, chlorpyrifos, acephate, propoxur, and deltamethrin, in Fengtai district, Beijing, China.Methods The B. germanica used in this study was the first filial generation (F1 generation) and that was bred in the laboratory followed by one-year normal feeding. The insecticide film method recommended by the World Health Organization was used to determine the median knock-down time (KT50) and the corresponding 95% confidence interval (95%CI), knock-down rate, and mortality rate of B. germanica exposed to the five commonly used insecticides and to assess the levels of resistance and the resistance abatement of B. germanica. Results The mean coefficients of resistance (R/S) of the F1 generation of B. germanica to beta-cypermethrin, acephate, deltamethrin, propoxur, and chlorpyrifos were 7.91, 1.90, 30.52, 4.56, and 2.06, respectively. The rates of resistance decline in B. germanica after one-year exposure to the five commonly used insecticides were 42.82%, 49.70%, 74.77%, 56.51%, and -24.19%, respectively. Conclusion Blattella germanica has developed different levels of resistance to the five commonly used insecticides in Fengtai district, Beijing. After feeding for one year in the laboratory, the rates of resistance of B. germanica declined for more than 40% for all insecticides except chlorpyrifos.
Objective To assess the effect of the EP-1 on the population reproduction of the desert hamster Phodopus roborovskii. Methods Baiting bags containing a mixture of wheat and contraceptive compound EP-1 were placed in the field of Hunshandake Sandland, Xilin Gol League, Inner Mongolia, in late April, 2003. Monthly live-trapping survey were conducted from June to October to investigate the impact of EP-1 on the reproductive parameters and structure of the P. roborovskii population. Results EP-1 did not influence the sex ratio of the P. roborovskii population during the breeding season. In the baited area, EP-1 resulted in a 70%-80% decline in the proportion of juvenile hamsters, which lasted over 4 months. EP-1 profoundly damaged the uteri of approximately 80% of adult female hamsters within 2 months and such impact lasted more than 5 months. In addition, EP-1 significantly reduced the average litter size, which was 1-3 times smaller in the baited area than in the control area. Conclusion In Hunshandake Sandland, a single delivery of EP-1 in spring is effective in controlling the population of P. roborovskii during the breeding season. However, the impact of EP-1 on the reproduction of P. roborovskii population declines over time, which may be explained by the dispersal behavior of P. roborovskii.
Objective To perform the phyletic classification of Calyptratae in Mount Wutai, Shanxi province, China. Methods The survey was conducted using the theory and methodology of insect taxonomy. Results A total of 111 species, 69 genera, and 7 families of Calyptratae were found in Mount Wutai, including 1 species and 1 genus in Scathophagidae, 12 species and 8 genera in Anthomyiidae, 6 species and 1 genus in Fanniidae, 41 species and 24 genera in Muscidae, 15 species and 9 genera in Calliphoridae, 19 species and 13 genera in Sarcophagidae, and 17 species and 13 genera in Tachinidae. There were 2 type species found from Mount Wutai. Conclusion Calyptratae in Mount Wutai is characterized by its abundance, species diversity, and endemism.
Objective To determine the species of hematophagous midges in Luobei county, Heilongjiang province, China.Methods Light traps and insect nets were used to capture the midges. Results A total of 26 827 bloodsucking midges (30 species, one genus) were captured in Luobei county from 2009 to 2013. A new species of the genus Culicoides, C. luobeiensis Liang et Liu, sp. nov., was reported. The new species was closely allied to C. subcircumscriptus Yu, 1982, but C. subcircumscriptus Yu, 1982 had the following distinct differences: presence of little pale spots on cell R5 and the distal portion of vena M1; in females, presence of sensilla coeloconica on segments 3, 11-14; in males, presence of spiculae on the ventral membrane of the ninth sternum, stout apicolateral processes on the ninth tergum, absence of the ventral root of basistyle, and absence of small pricks inside the paramere bases. C. alazanicus Dzhafarov, 1961 (♀) was recorded for the first time in China. Conclusion This investigation provides a basis for further study on the species distribution of hematophagous midges in Luobei county, Heilongjiang province. The type specimens are deposited in the Shenyang Military Command Center for Disease Control and Prevention (Shenyang 110034, China).
Objective To analyze the current running status of plague control and management information system in Hebei province, China, and to improve the accuracy and reliability of the data obtained from the system. Methods Plague surveillance monthly reports were compared with the direct network report data. Analysis and discussion were made on the problems emerging from the application of the system, as well as the issues identified from the work. Results The system operated smoothly, but problems remained such as cumbersome data entry procedures, incomplete data entry, and data entry error. Incomplete data entry was the most outstanding problem in direct network report, and for example, the net rate was 53.0%-80.2% for the pathogenic test, 25.0%-63.0% for the serum test, 66.0%-80.0% for the quadrant survey, and 42.3%-73.6% for the small rodent survey. Conclusion The plague control information system should be optimized and the team of primary health care staff should be strengthened in order to increase the accuracy and reliability of the network report and to improve the value of the system.
Objective To compare different methods for detection of Oncomelania hupensis eggs in the soil, and to evaluate the feasibility of snail egg hatching in a natural way or at a stable temperature. Methods Snails from Guichi district of Chizhou, Anhui province, China, were kept in the ponds of 4 square meters which mimicked natural ponds with 25, 50, 100, 200, 400, or 800 male or female snails per pond; the ratio of male and female snails was 1:1. Two years later, soils were taken from the ponds to measure the number of snail eggs and perform egg hatching experiments with four methods. Statistical analysis was performed for these methods. Results With each of the four methods, active snail eggs were detected or young snails were produced. Kruskal-Wallis H test showed no significant differences between the four methods in the detection rate of snail eggs or young snails. Log linear regression analysis revealed no significant correlation between the number of snails detected and the number of original snails in the pond (Y=1.7312Lnx-5.7060). No consistency was found for the four methods by Kappa test. Conclusion Active snail eggs present in soils can be hatched naturally or at a stable temperature.
Objective To investigate the epidemic of plague in the past 10 years along the Qinghai-Tibet Railway, and to provide a scientific basis for the prevention and control of plague in future. Methods The monitoring results and clinical data for the human plague epidemic along the Qinghai-Tibet Railway from 2003 to 2013 were collected and analyzed using descriptive epidemiological methods. Results The emergence of plague in both animals and humans mainly occurred in the areas of Geermu (Tanggulashan Township), Tianjun, and Wulan in the Qinghai section of the Qinghai-Tibet Railway from 2003 to 2013. Sixty-nine strains of Yersinia pestis and 86 sera with positive F1 antibody were detected in these areas; 7 cases of human plague occurred, and 3 cases died. Conclusion Serious epidemic of plague remains in the Qinghai section of the Qinghai-Tibet Railway. Frequent occurrence of plague between animals and sporadic human plague epidemic are mainly related to illegal marmot hunting in these key areas.
Objective To investigate the current status of rabies post-exposure prophylaxis from 2009 to 2013 in Qingdao, China. Methods The monthly data of rabies post-exposure prophylaxis were analyzed using descriptive method. Results From 2009 to 2013, there was an upward trend in the rabies exposure rate with an average of 518.26/100 000, and the highest rate was 1008.54/100 000 found in the Qingdao Economic and Technological Development Zone among all the county-level cities and districts. The incidence of exposure was higher in summer and autumn than in spring and winter, and the number of incidents from May to October constituted 64.34% of all incidents. The exposure rate was higher in males. The exposure rate in 0-14 years of age was 784.21/100 000 and the highest of all ages. The number of persons with degreeⅡand Ⅲ exposure accounted for 43.38% and 56.62%, respectively, of all exposures. Dog bites constituted 92.94% of all exposures. All exposed persons were inoculated with rabies vaccines and 1.00% of persons with degreeⅢ exposure were given passive immunizing agents. Conclusion During the period of 2009-2013, rabies exposure rate showed an increasing trend year by year in Qingdao. The focus should lie on rabies post-exposure prophylaxis and comprehensive measures must be taken for the prevention and control of rabies.
Objective To analyze the surveillance data of hemorrhagic fever with renal syndrome (HFRS) in Shenyang, China, from 2004 to 2013 and to assess the trend of HFRS epidemic in the past ten years. Methods Descriptive epidemiological methods were used to analyze the surveillance data of HFRS in Shenyang from 2004 to 2013. Results A total of 2253 cases of HFRS were reported in Shenyang from 2004 to 2013. The incidence and mortality showed a decreasing trend year by year. There was no epidemic outbreak, and all the cases were sporadic. Of all the HFRS cases reported, 70.88% (1597/2253) were observed in seven districts: Yuhong district, Heping district, Huanggu district, Tiexi district, Shenbei New Area, Dongling district, and Xinmin city. The incidence of HFRS showed marked seasonal characteristics, and the peaks of incidence appeared in spring and autumn-winter periods. The number of the cases reported in spring was higher than that in autumn-winter periods. The incidence rate in males was three times higher than that in females. The analysis of age groups and occupational distribution showed that the most affected individuals were young adults, and farmers or unemployed, respectively. Apodemus agrarius and Rattus norvegicus were the predominant reservoir hosts in the residential area and field, respectively. The population density of host animals and the virus-carrying rate were relatively stable. Conclusion The steady descending trend of HFRS epidemic in Shenyang could be related to the success of comprehensive prevention and control measures. Both the population density and the virus-carrying rate among the host animals remain high, so there is still a potential danger of HFRS epidemic.
Objective To analyze the epidemic characteristics and current status of plague in Hainan Tibetan Autonomous Prefecture, Qinghai province, China, and to provide a scientific basis for plague prevention and control in the future. Methods As a national monitoring station, the plague surveillance was carried out in Hainan prefecture according to the “National Plague Surveillance Programs”. The plague surveillance reports and human plague epidemic reports in Hainan prefecture from 2007 to 2012 were collected and analyzed using the descriptive epidemiological methods. Results Three positive canine serum samples were found in 2007 and 2009, four positive marmot serum samples and one positive corsac fox serum sample were found in 2010, and the serologic titers were as high as 1:20 480. These findings revealed the continued emergence of animal plague in Hainan prefecture. There was an outbreak of human pneumonic plague in 2009 since the first plague reported 60 years ago in Xinghai county, Hainan prefecture, which indicated a high risk of plague transmission from animals to humans in this region. Conclusion The animal plague epidemic is still active in Hainan prefecture, and the plague prevention and control face a great challenge in this area.
Objective To establish a comprehensive assessment model for plague surveillance for Qinghai province, China, and to evaluate the national-level surveillance stations in the natural focus of Himalayan marmot plague for improvement of performance and quality of plague surveillance. Methods A total of 25 comprehensive assessment indicators reflecting the surveillance quality were selected, which included the population survey of marmots and other small rodents, the flea index and burrow track fleas from the primary host of plague, marmots, and the plague bacteriological and serological measurements. The analytic hierarchy process (AHP) was used to establish a comprehensive assessment model for plague surveillance and to evaluate the plague surveillance in 4 national-level surveillance stations in the natural focus of Himalayan marmot plague in Qinghai. Results According to the scores obtained from the AHP model, the 4 national-level surveillance stations were in the order of Ulam county (1.9286), Gonghe county (1.3174), Golmud city (1.0692), and Yushu Tibetan Autonomous Prefecture (0.9477). Conclusion The results of plague surveillance evaluation based on AHP are reasonable and reliable. It provides strong evidence for the management and improvement of plague surveillance.
Objective To analyze the role of self-dead rodents in monitoring the Meriones unguiculatus natural foci of plague, and to provide guidance for the surveillance and early warning of animal plague. Methods The data and information collected during 2001 to 2010 from all monitoring sites of M. unguiculatus plague foci in the counties and districts of Ningxia Hui Autonomous Region were analyzed. The survey of nocturnal rodents and gerbils used the 5-meter clamp method and the pit-and-clip method, respectively. Results From 2001 to 2010, a total of 8675 wild rats were captured, belonging to 5 families, 7 genera, and 15 species, with M. unguiculatus and M. libycus being the predominant species. There were four annual animal plague epidemics within the 10-year period. The detection rate of bacteria in self-dead rodents was 61.54%, compared with 2.31/10 000 in the captured rodents. The database of M. unguiculatus plague foci in Ningxia from 2001 to 2010 was established based on those information. Conclusion Emergence of self-dead rodents in M. unguiculatus plague foci is an early sign of animal plague epidemic.
Objective To monitor the species composition and seasonality of calyptrate flies in four types of habitats in Yangpu district, Shanghai, China, and to provide a scientific strategy for fly control. Methods Cage traps were set up in the following four types of habitats: large-scale greenbelts (parks), greenbelts around restaurants, residential areas, and farm produce markets. Results A total of 1588 flies, belonging to 5 families, 25 genera, and 39 species, were captured from 2010 to 2013. The predominant strains were Muscina stabulans, Lucilia sericata, Aldrichina grahami, Anothomyia illocata, Chrysomya megacephala, and Muscina angustifrons. The seasonality showed peaks in June and September and the lowest population density in 2010. In the four types of habitats, the large-scale greenbelts showed the highest population diversity: 32 species, and the highest density was found in the farm produce markets with an average of 4.70 flies/cage·day. Conclusion The populations of calyptrate flies are abundant in habitats of Yangpu district, Shanghai. The predominant populations such as M. stabulans, L. sericata, and A. grahami should be the focus of fly control. Primary control measures should be taken in farm produce markets, and in June and September as the key time points for the prevention and control of fly-transmitted diseases.
Objective To use random amplified polymorphic DNA (RAPD) for species identification and origin determination of imported rodents. Methods Genetic DNA of rodents was extracted from tail tissue specimens and amplified by RAPD. Genetic polymorphisms in rodents were distinguished by differences in strong RAPD banding patterns. Results A quick DNA preparation method for sewer rats and their genetic maps were established. In accordance with different polymorphisms of 120 primers, a set of universal primers for sewer rats were synthesized, designated P1 (5'-TCG GCG GTT C-3'), P2 (5'-GAG AGC CGT C-3'), P3 (5'-ATG GCA TCT C-3'), and P4 (5'-CTT GGC ACG A-3'). Amplification of a target fragment (925 bp) in sewer rats using the universal primers all yielded good results. Conclusion Analysis of the degree of homology between individual DNA sequences and determination of their genetic distance allow identifying the origin of rodents as imported or not. The obtained data provide a reference for tracing the dispersal path and history of rodents and detecting early-warning signs of rodent-borne diseases.
Objective To investigate the species composition and seasonality of adult mosquito populations in Baoshan district of Shanghai, China, and to provide reference data for the prevention and control of mosquitoes and mosquito-borne diseases. Methods Labor hour method was used to determine mosquito population density. Surveillance data collected at the national vector monitoring site in Baoshan district of Shanghai during 2009-2012 were analyzed. Results Totally 5041 mosquitoes of 5 species were trapped during the four-year study period. Culex pipiens pallens was the predominant species of mosquitos in urban and rural residential areas (94.6% and 98.8%, respectively), while C. pipiens pallens and C. tritaeniorhynchus accounted for large proportions of mosquitos in the barn (46.6% and 23.5%, respectively). Average mosquito population density was lowest in the urban residential area, medium in the rural residential area, and highest in the barn (1.81 vs. 6.70 vs. 30.08 counts per labor hour). There were similar annual trends in seasonal fluctuations of mosquito populations, with high density generally in June to September and low density in January to April as well as November to December. The average value of mosquito population density index progressively increased over the four-year period. Conclusion No significant changes occurred in the species composition and seasonal fluctuations of adult mosquito populations in Baoshan district of Shanghai during 2009-2012. C. pipiens pallens was the predominant species of mosquitoes in urban and rural residential areas, which, together with C. tritaeniorhynchus, dominated the mosquito populations in the barn. It is recommended to carry out mosquito control from May to October in Baoshan district of Shanghai.
Objective To analyze the density of cockroaches in Neijiang, Sichuan province China, from 2011 to 2013, to understand their population structure, distribution, and seasonal dynamics, and to provide a scientific basis for cockroach prevention and control. Methods Three monitoring stations were selected in the city and the measurement was carried out monthly in the mid-month from 2011 to 2013. The population density, distribution, and seasonal fluctuation of cockroaches were determined using the sticky trap method in farm produce markets, restaurants, hotels, hospitals, and residential areas. Results From 2011 to 2013, a total of 6480 pieces of sticky traps were placed and reclaimed, and 22 478 cockroaches were captured with an average density of 3.47 cockroaches/trap. Blattella germanica was predominant and constituted 98.09% of all captured cockroaches. The cockroach density showed a bimodal seasonal fluctuation with peaks in April and July. Among all the habitats, the highest density was 9.68 cockroaches/trap found in the farm produce markets. Conclusion The predominant species of cockroaches in Neijiang is B. germanica. Cockroaches are widespread and the farm produce markets are the most important habitats of cockroaches. The comprehensive improvement of the market environment should be enhanced to effectively control the density of cockroaches.
Insect cytochrome P450s are well known to play an important role in the process of insecticide detoxification. Enhanced detoxification of insecticides is a common mechanism responsible for the development of resistance to various insecticides in insects. This article introduces the current advances in the study of insecticide resistance-associated cytochrome P450s and the potential involvement of cytochrome P450s in the resistance to relatively new insecticides in the house fly (Musca domestica).
Climatic factors affect the spread of dengue fever by influencing the development and reproduction of vector mosquito species, as well as amplification of viral pathogen in vectors. Evaluating the impact of climatic factors on disease spread and exploring the underlying mechanisms lay a foundation for improving the monitoring system of dengue fever and further implementing prevention and control measures. Under certain conditions, climatic factors such as temperature, light, precipitation, and relative humidity are closely related to the spread of dengue fever. Additionally, some extreme weather events affect the spread of this disease by influencing local microclimate. Therefore, it is recommended to include meteorological indicators in the existing monitoring system of dengue fever, thereby increasing the sensitivity of surveillance.
