ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective To analyze the feasibility of integrated monitoring of mosquitoes and mosquito?borne diseases, providing an integrated monitoring mode of vectors and the related diseases. Methods The integrated monitoring procedures for mosquitoes and mosquito?borne diseases were tested in two vector monitoring sites. Integrated monitoring was conducted in cities and counties under the collaboration of relevant institutions and personnel. The lamp trap method was used for adult mosquito integrated monitoring from June to October in 2009. Results An executive office was set up under the Zhejiang Center for Disease Control and Prevention (CDC) to deal with the overall coordination. Ningbo CDC completed the integrated monitoring of mosquito density, seasonal fluctuation and mosquito?borne diseases without external aid. Jiande CDC finished the field investigation of the above monitoring, and the laboratory specimen test was performed by the Zhejiang CDC. These accomplishments required extraordinary institutional coordination and a large number of personnel. In 2009, Ningbo reported 48 cases of malaria with an incidence rate of 0.73/105; one case of dengue fever with an incidence rate of 0.02/105; 18 cases of Japanese encephalitis (JE) with an incidence rate of 0.28/105; and 1 death with a mortality rate of 5.56%. Jiande reported no cases of malaria, dengue fever and JE. A total of 22 108 mosquitoes were captured in Ningbo, with a density of 9.60/h; and 945 were captured in Jiande, with a density of 4.92/h. Culex tritaeniorhynchus was the predominant species in Ningbo, accounting for more than 90%, followed by Cx. pipiens pallens, where as Aedes albopictus accounted for only 0.14%. In Jiande, Cx. pipiens pallens was predominant, followed by Anopheles sinensis; no Ae. albopictus was captured. Fluorescent PCR detection of 1973 Cx. tritaeniorhynchus in Ningbo showed two positive specimens for JE, with the minimum positive rate of 0.10%. Nested PCR detection of 225 Cx. pipiens pallens in Jiande resulted in negative for yellow virus. Conclusion The integrated monitoring of mosquitoes and mosquito?borne diseases is feasible. It is suggested to strengthen the research with regard to the integrated monitoring, early warning, control strategies and measures of mosquitoes and mosquito?borne diseases.
Objective The susceptibility of the larvae and adult mosquitoes of Culex tritaeniorhynchus in Donggang city, Liaoning province to commonly used insecticides was evaluated to determine their insecticidal resistance and identify the relationship between the resistance levels of the larvae and adult mosquitoes, providing the basis for chemical control of the mosquitoes. Methods A large number of adult Cx. tritaeniorhynchus were collected outdoors in the peak seasons to obtain the first filial generation, fed with the blood of mice, for testing. The impregnation method and the contact exposure method, as recommended by the WHO, were employed to determine the susceptibility of the larvae and adult mosquitoes of Cx. tritaeniorhynchus to commonly used insecticides, respectively, for calculating the LC50 and the corresponding 95% confidence limits (95%CI) for the larvae, and the knockdown rate and mortality of the adult mosquitoes for comparison of their resistance levels to commonly used insecticides. Results The LC50 and the corresponding 95%CI of deltamethrin, beta?cypermethrin, and permethrin for Cx. tritaeniorhynchus larvae were 0.002 098 (0.001 575- 0.002 866), 0.013 80 (0.011 43-0.016 64) and 0.016 51 (0.014 00-0.019 49) mg/L, respectively; the LC50 and the corresponding 95%CI of dichlorvos, temephos and fenitrothion were 25.3479 (21.4949-28.3828), 48.3763 (31.7172-92.4088) and 0.1685 (0.1085-0.2679) mg/L, respectively; the LC50 and the corresponding 95%CI of BPMC were 0.2874 (0.1803-0.4268) mg/L. Compared to the susceptible strains reported in previous literature, the larvae of Cx. tritaeniorhynchus had the resistance coefficients of 5.3, 2.3 and 3.3 to deltamethrin, beta?cypermethrin and permethrin, respectively, and 396.1, 40 313.6 and 34.0 to dichlorvos, temephos and fenitrothion, respectively; the mortality rates of the adult Cx. tritaeniorhynchus exposed to 0.05% deltamethrin (contact for 1 h), 0.25% permethrin (3 h), and 1% fenitrothion (1 h) beyond 24 h were 15.9%, 27.7% and 8.2%, respectively. Conclusion The larvae of Cx. tritaeniorhynchus in Donggang city, Liaoning province developed high resistance to organophosphate and low resistance to pyrethroids. However, the adult mosquitoes were highly resistant to deltamethrin, permethrin, and fenitrothion. The resistance levels of the larvae and adult Cx. tritaeniorhynchus to pyrethroids were inconsistent.
Objective The current drug resistance of Musca domestica in different habitats in Nanchang was determined to provide the basis for proper administration of pesticides. Methods The micro?drop method was applied. Results The M. domestica in different habitats in Nanchang had developed varying degrees of tolerance or resistance to dichlorvos, propoxur, deltamethrin, beta?cypermethrin, beta?cyfluthrin and d?phenothrin. The LD50 of the M. domestica strains from the refuse transfer stations were 0.1664, 31.9389, 0.0348, 0.0498, 0.0059 and 0.2551 μg per fly, respectively; the LD50 of the M. domestica strains from the farmer’s markets were 0.1447, 40.7779, 0.0581, 0.0421, 0.0283 and 0.1722 μg per fly; those of the strains in catering industry were 0.1873, 51.7781, 0.0066, 0.0129, 0.0102 and 0.1990 μg per fly; and those of the strains from the residential areas were 0.2828, 39.8730, 0.0416, 0.0798, 0.0490 and 0.2342 μg per fly. Conclusion The M. domestica in different habitats in Nanchang demonstrated intermediate to high resistance to dichlorvos but low tolerance to propoxur, as well as varying resistance to pyrethroid insecticides. Therefore, it is recommended to adopt integrated control measures and scientifically and properly administer pesticides in order to delay or avoid the occurrence and development of drug resistance in houseflies for effective control of M. domestica populations.
Objective The daily intake in and preferences for field crop seeds and fruits in Bandicota indica were measured and determined, and the relationship between their food intake and the gender, age, weight and seasonal changes was analyzed in order to provide the basis for determination of the hazard of B. indica and development of sustainable control technology. Methods The animals were artificially fed in the laboratory and subject to both unselective and selective experiments indoors. Results Different crops had the respective intake masses as follows: dry rice (37.48±5.98) g, fresh rice (95.57±7.85) g, sweet potatoes (229.84±26.86) g, sweet corn (259.12±27.68) g, peanuts (101.92±20.40) g, soybeans (40.42±6.56) g, vegetables (377.96±52.33) g, and sugarcane (262.29±34.77) g. The intake masses of all crops in male rats were greater than those in female ones except for soybeans, while the intake masses of all crops in infant rats where higher than those in adults and subadults except for sugarcane. A significant to extremely significant linear correlation between the food intake and body weight was also shown. As for the seasonality, the food intake peaked in winter, moderated in autumn and reduced to the smallest in summer. The results of selective experiments showed that the preferences of B. indica for different crops were in descending order as follows: fresh rice, sweet corn, sweet potato, dried rice, peanuts, soy, sugarcane and vegetables. Conclusion The food intake of B. indica was highly related to the dry matter content and nutritional value, animal metabolism, growth rate and external environmental conditions. The preference index can be used to accurately reflect the different degrees of food preferences in rodents.
Objective The source of noticeably increased blood cells in third?instar Musca domestica larvae infected with Escherichia coli (E. coli) was investigated. Methods Changes in the total hemolymph counts (THC) of the third?instar M. domestica larvae infected with E. coli in 4, 8 and 16 h and those of the control group were followed and compared. A flow cytometry was used to identify the changes in the blood cell cycle of the third?instar larvae of each group before and after infection. Results The THCs in 4, 8 and 16 h after infection were significantly elevated compared with that in the control group. Peaking in 8 h after infection, the highest THC reached (38 920±2274)/μl. The blood cell proliferation index (PI) of the control group was 15.98%. After infection, the G2/M phase and S phase cells increased in each group with significantly increased PI values. Peaking in 4 h after infection, the highest PI value reached 44.34%. Conclusion The blood cells of M. domestica larvae have the ability to divide as a supplement to the hematopoietic function.
Objective Attracting effect of fecal extract of the Blattella germanica of different ages and genders on themselves was measured in the present study in order to provide more effective guidance on the chemical control of B. germanica. Methods B. germanica feces were immersed in organic solvents to produce the extract, of which the attracting effect was measured by a four?arm olfactometer. Results The ethanol fecal extract of early nymphs was the best to attract early nymphs, late nymphs, male adults and female adults, with the attraction rates of 39.72%, 40.56%, 38.33% and 34.17%, respectively, followed by fecal extract of late nymphs, the attraction rates of which were 30.56%, 30.56%, 27.22% and 26.11%, respectively. The extracts of male and female adult feces were the worst at attracting, though the one of male adult feces had an attraction rate of 22.22% to female adults, and that of the female adult fecal extract reached 24.72% to male adults, both higher than the effect of nymph fecal extracts and that between the same gender. The effectiveness of toxic baits increased significantly when added a certain amount of the ethanol extracts of early or late nymph feces; the 24 h kill rate of deltamethrin baits increased from 26.00% to 54.00% and 48.00%, respectively; the 24 h kill rate of phoxim baits increased from 20.00% to 48.00% and 40.00%, respectively. Conclusion The fecal extract of early nymphs had a favorable attracting effect on the nymphs of all ages and male and female adults, while the fecal extract of a certain gender satisfyingly attracted the opposite. Mixed with the ethanol fecal extract of early and late nymph, the toxic baits demonstrated improvement in the killing efficiency.
Objective The vectors variation trends before and after impoundment of the Three Gorges Reservoir in Yichang were monitored and analyzed for timely implementation of the countermeasures. Methods The indoor and outdoor rodent density, mosquito density in residential houses and livestock pens, and species composition of rodents and mosquitoes were determined using the night trap method and the labor hour method. Results No significant changes were observed in the rodent density after impoundment of the Three Gorges Reservoir in Yichang (t＝0.52, P＞0.05). The annual variation of the rodent density constituted a primary decline followed by an increase. As for the small mammal species composition, the indoor and outdoor dominant species before impoundment were Rattus norvegicus and those of the genus Sorex, accounting for 71.07% and 42.11%, respectively. The dominant species after impoundment, indoor and outdoor, were both R. tanezumi, accounting for 41.67% and 42.86%, respectively. The mosquito density in residential houses did not change significantly after impoundment (t＝1.29, P＞0.05), whereas the mosquito density in livestock pens increased significantly (t＝5.01, P＜0.01). In regard to the mosquito species composition, Anopheles sinensis and Culex pipiens pallens were the dominant species before impoundment in residential houses and livestock pens, respectively, accounting for 38.50% and 34.65%; Armigeres subalbatus and An. sinensis were the dominant species after impoundment, accounting for 37.21% and 23.18%, respectively. Conclusion The environmental changes due to impoundment of the Three Gorges Reservoir in Yichang had led to the alteration in rodent species composition, in addition to significantly increased mosquito density in livestock pens and altered mosquito species composition. It is suggested that vector monitoring should be strengthened to provide the decision?making basis for effective prevention and control of the occurrence and prevalence of vector?borne diseases.
Objective Several kinds of food are preferably palatable to Oncomelania hupensis. The most effective food?based attractants were identified in this study, and the application of these attractants in molluscicidal pellets was evaluated. Methods The attracting effects of the mixture of Sedum sarmentosum leaves (food M), and fermented cornstarch (food C) were compared under various environmental conditions with different humidity and light levels. The two were combined with the water extract of Gynostemma pentaphyllum, a molluscicidal plant, to produce molluscicidal pellets, respectively, for experiment on the snail killing effects. Results Statistically significant differences were shown in the attracting effects of different food attractants on O. hupensis under room temperature (25 ℃). The attracting effects were greatly humidity?dependent, as the ones under an 80% relative humidity were stronger than those under a 40% relative humidity. The multi?factor analysis of variance showed that humidity (F1，64＝60.209, P＜0.001), snail food (F3，64＝344.820, P＜0.001) and time (F3，64＝724.429, P＜0.001) had substantial impact on the attracting effects. The attracting effect of snail food M was greater than that of snail food C. Light had little influence on attracting O. hupensis. The molluscicidal pellets made of food M and C increased the 7 d snail mortality rates by 42.68% and 30.00% as compared to the control and experimental groups, respectively. Conclusion Food M had a relatively stronger attracting effect on O. hupensis under 25 ℃ and 80% relative humidity; when added in molluscicidal agents, it greatly increased the snail mortality.
Objective The bioactivity of the essential oils from Mosla chinensis against Aedes albopictus was determined, and the chemical composition of the essential oils was analyzed to provide the basis for development of botanical mosquito control agents. Methods The essential oils were extracted from M. chinensis using steam distillation. The bioactivity of the essential oils against 4th instar Ae. albopictus larvae and pupae was determined using immersion tests, and the repellent activity was examined using human skin tests. The gas chromatography?mass spectrometry was employed to analyze the chemical composition of the essential oils from M. chinensis. Results （1） The 24 h LC50 values for 4th instar Ae. albopictus larvae and pupae were 78.820 μg/ml and 122.656 μg/ml, respectively; （2） application of 1.5 mg/cm2 pure essential oils provided (2.330±0.167) h of complete protection time against adult mosquitoes, and 56% of the protective effects remained beyond 6 h; and （3） a total of 44 compounds were detected from the essential oils and 39 were identified, accounting for 98.67%. The main components included p?cymene (23.17%), 5-isopropyl-2-methylphenol (16.83%), thymol (14.92%), Benzene, 2-methoxy-4-methyl-1-(1-methylethyl) (12.89%), eucalyptol (8.48%), caryophyllene (3.96%), α?caryophyllene (3.16%) and thymol acetate (2.71%). Conclusion The essential oils from M. chinensis had strong bioactivities on both Ae. albopictus larvae and adult mosquitoes. New natural active compounds may be found from these essential oils for development of environment?friendly mosquito control agents.
Objective To study the mechanism of the toxicity of celangulin against Aedes albopictus larvae and its influence on various aspects, such as the growth and development of mosquito larvae. Methods Conventional biological approaches were employed for determination of the toxicity and the impact on the larva growth and development: the changes in the gastrointestinal morphology were identified by HE staining; the antifeedant activity was measured through the colorimetric determination of chromium oxide. Results With increasing concentrations, celangulin had strengthening toxicity against the fourth instar larvae of Ae. albopictus, with the LC50 of 22.66 (18.38-27.95) mg/L and LC95 of 84.51 (60.87-142.27) mg/L. Celangulin could reduce the pupation rate and extend the average pupation time and the average eclosion time of Ae. albopictus larvae, though it had no significant effect on the eclose rate. As the concentration of celangulin increased, its antifeedant activity became stronger, leading to gastrointestinal morphological changes: brush border loss and midgut degeneration and disintergration. Conclusion Celangulin was able to kill Ae. albopictus larvae through gastrointestinal toxicity, antifeedant activity and contact toxicity, and inhibit their growth and development.
Objective The efficacy of fipronil baits against Solenopsis invicta was determined and the technical specifications for application of the baits were developed. Methods A combination of small?scale field experiments and single nest experiments was used. Results The results of small?scale field experiments using the three concentration gradients, 0.0005%, 0.005% and 0.05%, showed that the 0.05% fipronil baits had the best killing effect, which was evident beyond 3 d after application on a dose of 6 g for each ant nest in the experiment areas. The adjusted decrease rate of active ant nests was 9.52%, and that of worker ants was 43.94%. Significant control effects were observed beyond 6 d after application of the baits, the adjusted decrease rate of active ant nests being 74.03% and that of worker ants 98.05%. At day 27 and 30, both decrease rates reached 100%. Additionally, the baits had no obvious effect on any other arthropod. The results of single nest experiments showed that the optimal dosage of the 0.05% fipronil baits for 25-30 cm mature nests was 5 g/nest. It was shown that the active time of feeding for S. invicta was beyond 17:00 in summer and from 9:00 to 17:00 in winter. Evenly spraying the baits on the surface of ant hills would contribute to the shortest time for worker ants to deposit the baits. Conclusion The 0.05% fipronil baits can rapidly and completely kill S. invicta ants while sparing non?target arthropods. The technical specifications for application are as follows: based on the recognized optimal dosage, 5 g/nest, for 25-30 cm mature nests, the actual application amount can be adjusted according to the size of nest. The optimal application time was after 17:00 in summer and from 9:00 to 17:00 in winter. The best way to apply the baits is by evenly spraying them on the surface of ant hills.
Objective The optimal dose?duration relationship of a broad?spectrum fumigant?sulfuryl fluoride, was analyzed in this study. Methods Each group of Blattella germanica was fumigated to reach static inhalation of the agent through the respiratory tract. Poisoning symptoms and death counts were observed, and a quadratic response surface regression model was established to fit and predict the experimental data, which were then verified under simulated scenes. Results The analysis of variance showed statistical significance of the response surface model (F＝75.12, P＜0.0001), the total coefficient of determination R2＝0.7848. The simple, quadratic and cross terms of the model were all statistically significant, their coefficients of determination being 0.1493, 0.1902 and 0.4453, respectively. The on?site simulation experiment demonstrated a 100% cockroach kill rate based on the dose and fumigation duration predicted by the model using sulfuryl fluoride. Conclusion The optimal dose?duration of sulfuryl fluoride fumigation for cockroach control was basically identified through this study, providing the basis for determination of proper dose and duration in the future container fumigation.
Objective To evaluate the impact of compound levonorgestrel tablets on the fertility of female mice for providing the basis for rodent control with contraceptives. Methods A total of 60 female mice were randomly divided into a control group and two experimental groups. The mice in the control group were normally fed, while those in the experimental groups were fed 12 and 24 mg/kg of toxic baits, respectively. The female mice were paired with male mice in a ratio of 2∶1 beyond 48 h after feeding for mating test to determine their fertility. Results The fertility rates of the 12 mg/kg and 24 mg/kg groups were 15.00% and 0, respectively, lower than that (80.00%) of the control group (χ2＝33.43, P＝0.00). The average litter sizes of the 12 mg/kg and 24 mg/kg groups were 6.25 and 4.75, respectively, both lower than that (10.70) of the control group (F＝10.30, P＝0.00). The average time from the pairing to birth of the two experimental groups was 36.85 and 42.60 d, respectively, both longer than that (27.25 d) of the control group (F＝9.65, P＝0.00). The average birth control time of the 12 mg/kg and 24 mg/kg groups was 9.60 and 15.35 d, respectively. Conclusion Compound levonorgestrel tablets significantly compromised the fertility of female mice, indicative of the potential value of this drug in rodent control.
Objective To establish a TaqMan probe?based fluorescence quantitative PCR assay for rapid detection of Dengue virus type 1 (DV1) to facilitate the clinical diagnosis. Methods A set of specific primers and TaqMan probes were designed for the RT?PCR according to the conservative gene sequences at the 5′-terminal non?coding regions of DV1. A total of 40 sera samples were collected from patients with dengue fever, and four serotypes of standard DV strains were used as the control. The specificity of the established TaqMan?based fluorescence quantitative PCR assay was determined using the RNA templates obtained through in vitro transcription in the RT?PCR of the standard strains as a positive control. The sensitivity of the assay was then compared with that of the DV?IgM/IgG?based ELISA by assessing the sera samples. Results The lowest detection limit of the established method was approximately 10 gene copies per reaction. As to the positive results among the sera samples collected from patients at different stages after onset, the RT?PCR had the highest positive detection rate during the first three days after onset (81.25%), while the ELISA?IgM had the highest positive detection rate from day 4 to day 6 after onset (85.00%). After 7 d, ELISA?IgG had the highest positive detection rate (75.00%). Conclusion The established RT?PCR assay was a highly sensitive, specific and reproducible approach for rapid detection of DV1, conducive to the early diagnosis of dengue fever.
Objective The dominant species of ticks in Zhejiang province was identified and detected for Bartonella infection in order to provide the basis for the control and prevention of Bartonella human infection. Methods Engorged adult ticks were collected from the body surface of the animals in Tiantai, Jindong and Jiangshan areas, and the prevalence of Bartonella was detected using PCR. Sequencing analysis was then performed to identify the Bartonella species. Results All captured ticks were Ixodes sinensis, with the positive rates of 42.3%(11/26), 6.7%(2/30) and 3.3%(1/30) in Tiantai, Jindong and Jiangshan areas, respectively. The average positive rate was 16.3%. The detected Bartonella had the closest genetic relationship with Bartonella rattimassilensis, followed by the human pathogenic B. grahamii. Conclusion The presence of Bartonella infection in ticks in Zhejiang posed the risk of transmission to humans, and hence the corresponding control measures should be taken.
Objective The prevalence of hemorrhagic fever with renal syndrome (HFRS) was monitored and analyzed to reveal the epidemiologic characteristics of HFRS in Wenzhou, in order to provide the basis for development of the control and prevention strategies for HFRS. Methods A descriptive epidemiologic approach was employed to analyze the prevalence of HFRS in humans in Wenzhou from 1981 to 2008. Cage traps were used to capture small mammals for investigation of the species composition of animal hosts. The indirect immunofluorescence assay was used to detect the Hantavirus (HV) antigens in animal lungs, which were then genotyped by PCR. Results A total of 383 cases were reported from 1981 to 2008 with an average incidence rate of 0.20/105. There were 13 death cases, with a fatality rate of 3.39%. The cases were distributed in all the ten counties (cities, districts) of the city, particularly in Ruian, where the number of cases accounted for 53.78%. Significant seasonality was observed as the prevalence peaked in winter (from November to January of the following year) when the number of cases accounted for 41.25%. Most cases were 20 to 50 years, accounting for 74.76% of the total number. In regard to the monitoring of host animals, the outdoor capture rate was 7.16% and the indoor one was 7.88%. The dominant species outdoors was Niviventer confucianus, followed by Rattus losea; the dominant species indoors was R. norvegicus, followed by R. tanezumi. A total of 422 rat lungs were investigated, resulting in nine HV antigen?positive specimens with the positive rate of 2.13%. The sole genotype of the extract of viral RNA in the HV antigen?positive rat lung tissues was SEOV. Conclusion Comprehensive prevention and control measures, including strengthened monitoring, deratization and vaccination shall be implemented to effectively prevent HFRS epidemic.
Objective Borrelia burgdorferi were isolated from captured ticks in the border areas between Guangxi and Guizhou, in order to identify the vector of Lyme disease in Guangxi Zhuang Autonomous Region and Guizhou province. Methods The BSK?Ⅱ culture media were used to isolate B. burgdorferi from ticks. The 5S-23S rRNA gene spacer region of the isolates was amplified by the PCR, and the product was cloned and sequenced. The sequencing results were compared with the 5S-23S rRNA gene spacer region of the B. burgdorferi strains from the gene bank and analyzed for the homology to identify their genotypes. Results One B. burgdorferi was isolated from the captured Ixodes sinensis (named QLT1). The isolate was identified as the genotype B. valaisiana. Conclusion I. sinensis is the likely vector of Lyme disease in Guangxi Zhuang Autonomous Region and Guizhou province.
Objective The study was conducted to establish a molluscicide with strong snail?killing effects and low toxicity to aquatic organisms. Methods Immersion tests using 100, 200, 400 and 800 mg/L carbamide and spraying tests using 15, 20, 25 and 30 g/m2 carbamide were conducted under laboratory conditions to measure the molluscicidal effects, respectively, which were then compared to the effect using 2 g/m2 niclosamide. Results The Oncomelania hupensis mortality rates ranged from 3% to 6% after carbamide immersion at the concentration of 100-800 mg/L, suggesting no statistical difference from those in the control group (P＞0.05). The 1, 3 and 5 d O. hupensis mortality rates in laboratory spraying tests reached 91%, 90% and 95% in the 30 g/m2 group, while those in the 2 g/m2 niclosamide group were 97%, 96% and 98%, indicating no statistically significant difference (P＞0.05). Conclusion Under laboratory conditions, carbamide immersion was ineffective in killing snails, whereas carbamide spraying had the same molluscicidal effects as niclosamide did.
Objective To evaluate the insecticidal resistance of Culex pipiens pallens and Musca domestica in Zhoushan city for providing the basis for studying the mechanism of resistance development in mosquitoes and flies and developing control and prevention measures. Methods The median lethal concentration (LC50) for Cx. pipiens pallens larvae was determined by the impregnation method; the median lethal dose (LD50) for M. domestica was determined by the topical application method. Results The resistance coefficients of Cx. pipiens pallens natural strains were between 1.5 and 10.8 to the following insecticides in descending order: 10.8 to beta?cypermethrin, 9.4 to permethrin, 5.3 to deltamethrin, 4.3 to tetramethrin, 4.1 to dichlorvos, and 1.5 to BPMC. The resistance coefficients of M. domestica natural strains were between 4.4 and 29.9 to the following insecticides in descending order: 29.9 to deltamethrin, 23.6 to beta?cypermethrin, 17.2 to cypermethrin, 8.8 to permethrin, 8.4 to dichlorvos, and 4.4 to tetramethrin. Conclusion The Cx. pipiens pallens and M. domestica in Zhoushan city demonstrated different degrees of resistance to the six insecticides; the resistance to pyrethroid insecticides was higher than to the other types, which may be related to the strategy of insecticidal application in the city.
Objective The effects of the mosquito repellents of different formulas were evaluated to identify the optimum formula. Methods Both the laboratory (GB/17322.10-1998) and on?site repellent effects of the agents were measured. Results Among the twenty tested formulas, ten demonstrated the effective protection rates of greater than 80% against laboratory?reared Aedes albopictus with an average repellent duration of above 10 h. Three groups of different formulas were tested in two separate on?site tests, resulting in the average effective protection durations of 4.8, 4.5 and 4.8 h, respectively. Conclusion The on?site test results, which were not as good as the laboratory ones, might be due to loss of repellents through rubbing or skin absorption given heavier sweat and more intense activities in summer. Since different formulas were used in the laboratory and on?site tests, further tests are required to confirm the repellent effects of the formulas under the same circumstances.
Objective To clarify the geographical distribution of Aedes albopictus in the Yangtze River basin in Gansu province. Methods Curtain traps, mosquito suction tubes and electric suction devices were used to capture blood?sucking female mosquitoes resting on the human body. Insect?catching nets were used to capture male mosquitoes. Results Liangdang county, Hui county, Cheng county, Xihe county, Li county, Kang county and Wudu district in the Yangtze River region in Gansu province were investigated. Ae. albopictus were found in Liangdang county, Hui county and Cheng county. A total of 49 breeding habitats for various species were investigated, eight of which were identified as the ones for Ae. albopictus, accounting for 16.33%. These breeding habitats were mostly scrap tire recovery and processing plants. Conclusion The newly recorded geographical distribution of Ae. albopictus in the Yangtze River region in Gansu province provided the key evidence for the northwest ward expanding boundary of Ae. albopictus in China.
Objective Rodent infestations in ports were assessed by comparing the consumption rates of various feed. Methods The indoor and outdoor rodent activities at all types of institutions of the land, sea and air ports in Yancheng city were studied. The distribution tendency of positive frequencies was plotted based on the feed consumption rates to establish the indicators for rodent infestations. Results In light of the health quarantine practices, the grading standards for assessment of rodent infestations were established according to the range of the mean positive rate, dispersion and frequency distribution theory relating to rodent activities, as follows: level Ⅰ (hazardless), with the infestation rate of 0-2%; level Ⅱ (mildly hazardous), with the infestation rate of ＞2%-10%; level Ⅲ (moderately hazardous), with the infestation rate of ＞10%-30%; and level Ⅳ (severely hazardous), with the infestation rate of ＞30%. Conclusion The proposed grading standards for assessment of rodent infestations in ports based on the feed consumption rates may be used separately or in combination with rodent tracing methods for large?scale rodent monitoring in ports.
Objective Deratization was performed in the inundated area of the Kangyang hydropower station on the Yellow River and the rat density, species and distribution were investigated in the area to prevent the outbreak of rodent?borne diseases due to changes in the ecological environment and rodent migration brought about by reservoir construction and water retention. Methods Chemical rodent control approaches were applied. Rat traps were used to investigate the rat density for comprehensive analysis. Results The rat density was 7.55% before deratization and 0.84% after deratization. The control rate was 88.87% as anticipated. The dominant species was of Insectivora. Conclusion The key areas in rodent control were the farming areas and residential areas. Bromadiolone was highly palatable to rats and remarkably effective in rodent control.
Objective The species variation of and seasonal fluctuations in the vector of Japanese encephalitis in Wuhan from 2006 to 2009 were investigated to provide the basis for the prevention and control of the disease and the vector mosquitoes. Methods The lamp trap method was applied. Results A total of 48 097 mosquitoes of 6 species, 4 genera and 1 family were captured from 2006 to 2009. The dominant species was Culex tritaeniorhynchus, accounting for 78.1% of the total captures. Marked seasonal fluctuations in the adult mosquito density were observed in the district; the activity peak was usually from June to August, while adult mosquito activities substantially weakened from January to March and from November to December. Conclusion The seasonal fluctuations in the number of Cx. tritaeniorhynchus, the dominant species in Huangpi district, were noticeable. In preliminary conclusion, Cx. tritaeniorhynchus is the major vector of Japanese encephalitis in the district.
Objective To get an insight into the mosquito density in Shunyi district, Beijing and the seasonal fluctuations to provide the basis for developing mosquito control programs. Methods The CO2 mosquito trap lamps were used to monitor the mosquito density. Results A total of 3019 mosquitoes were captured from 2005 to 2008, with the average mosquito density of 6.99 per (light·h). The dominant species was Culex pipiens pallens. The interannual fluctuations of the mosquito density from 2005 to 2008 followed a single?peaked curve, the peak value appearing in 2006. The habitats in descending order of the mosquito density were parks, residential areas, and hospitals. Analysis of the mosquito density on a monthly basis from 2005 to 2008 revealed that the peak density was usually evident around July. Conclusion The characteristics of the mosquito population density in Shunyi district and the seasonal fluctuations therein were basically revealed, providing the basis for further implementation of effective mosquito control and prevention. It is recommended to strengthen mosquito control during the high density seasons, and to improve the research on the long?term monitoring, early warning and control strategies and measures for mosquitoes and mosquito?borne diseases.
Objective To evaluate the specificity and sensitivity of the newly developed colloidal gold reagent for tsutsugamushi antibody detection. Methods A micro?indirect immunofluorescent assay (IFA) was performed to measure the tstsugamushi IgG antibody level in the serum samples of febrile patients, and 242 negative and strongly positive serum samples were drawn for determination of IgM, IgG and total antibody levels of Orientia tsutsugamushi using three colloidal gold reagent strips. If the control group was eligibly founded, the presence of red bands was indicative of positive results. Statistical analysis of the above results was then conducted. Results The sensitivity of the colloidal gold immunochromatographic assay for tsutsugamushi IgM, IgG and total antibody was 62.25%, 30.12% and 93.98%, respectively; the specificity was 98.11%, 98.74% and 96.23%, respectively. The results of IgM and IgG levels were statistically different from the IFA measurements, whereas that of total antibody was not (P＜0.05, P＜0.05 and P＞0.05, respectively). Conclusion Statistically significant differences were shown between the results of IgG and IgM antibody reagent strips and that of the IFA, whereas no significant difference was shown between the results of total antibody. Therefore, the newly developed assay could be a substitute for the IFA in tsutsugamushi antibody detection.
Objective The host animals and vector insects were monitored for early detection of plague epidemic and timely implementation of control measures. Methods Live rats were captured with cage traps, and taxonomically identified. The liver, spleen and sera samples were collected from the rats for detection of F1 antibodies and fleas. The rodent density, flea?carrying rate and flea index were then calculated. Results The dominant species of indoor rats were Rattus norvegicus and R. tanezumi, and the ones of outdoor rats were R. losea and Bandicota indica. The average rodent density, indoor and outdoor, reached 7.46% and 2.90%, respectively. The average flea?carrying rate of indoor rats was 42.00% with the total flea index of 1.19. The significantly dominant parasitic flea was Xenopsylla cheopis. Conclusion Although the species composition of hosts and vectors in historically epidemic areas remained stable with low density and a declining flea index, it is desirable to perform the monitoring for timely detection of abnormal signals, so as to implement the necessary measures to prevent the recurrence of plague.
Objective The investigate the species composition of cockroaches in and around the new campus of Zhengzhou University, and to identify the species of individuals. Methods Cockroach adults, nymphs and eggs were collected from different locations such as the dormitories and canteens at the campus, which were placed in 95% ethanol and taken back to the laboratory. The species of these specimens were finally identified in accordance with the classification standards for the order Blattodea after morphological observation and internal anatomy. Results All identified specimens belonged to two closely related species of a same genus of a same family, namely the Blattella germanica and Blattella lituricollis. The dominant species was the B. germanica, and B. lituricollis was the first record in Henan province. Conclusion The relevant authorities shall attach importance to the first discovery of B. lituricollis in Henan province and develop reasonable control and prevention strategies in a timely manner.
Objective The classification of blood?sucking midges in Jilin province was investigated. Methods Curtain traps, lamp traps and capture nets were used to collect midges in Jilin province. The literature related to the blood?sucking midges in the province was reviewed. Results A total of 41 species of 2 genera of blood?sucking midges were known in Jilin province, including 39 species of the genus Culicoides and 2 spcies of the genus Lasiohelea. The major differential characteristics and measurements of the blood?sucking midges in Jilin were documented to create a table of index to the species?specific midges of both genders of the genus Culicoides. Conclusion This study provided the basis for further development of the ecology, vector competency and prevention and control of the blood?sucking midges in Jilin province.
The mite?borne hemorrhagic fever with renal syndrome (HFRS) has been attracting domestic and foreign controversies in recent years. Based on a large number of field investigation and experimental studies, Chinese scholars have proved the existence of the mite vector of HFRS and its possible role. This paper reviews the epidemiologic, experimental and molecular biologic basis of the HFRS of Apodemus type and Rattus type transmitted by gamasid mites, as well as the research advance in the animal hosts.
The DNA barcode technology enables rapid, accurate detection and identification of species through the use of short standardized DNA fragments. This paper reviews the major research methods, advancing progress and current difficulties and controversies of DNA barcodes, the possibility of global adoption of this technology and the highlights in the DNA barcode research at the present, and analyzes the prospect of domestic application of this technology.
Natural disasters have been increasing in recent years, bring about a number of injuries and deaths, and might cause epidemics of some infectious diseases and social unrest in some areas. The natural disasters have important influences on the growth and reproduction of vector mosquitoes and are closely related to the transmission of malaria after disasters. It is very important to understand the effects of natural disasters on malaria for the prevention and control of malaria related to the natural disasters. The article reviews some recent advances on the influences of natural disasters on malaria, risk factors and surveillance of malaria in recent years.
Caenorhabditis elegans, studied in great detail, is simple and cheap enough to be used as a new model organism for analysis of bacterial pathogens. Currently, it is utilized to identify the virulence factors, pathogenetic mechanisms, host?pathogen interactions, biofilm formation and drug resistance of bacteria such as Pseudomonas aeruginosa, Enterococcus faecium, Staphylococcus aureus, Shigella flexneri, Pseudomonas aeruginosa, Yersinia, Listeria, Salmonella enterica, Burkholderia, Streptococcus pyogenes, Salmonella typhimurium, Bacillus thuringiensis, Serratia marcescens, Cryptococcus and Microbacterium nematophilum. Since C. elegans feeds on bacteria, determination of bacterial pathogenicity is based on variations in the survival curve of strains that have consumed the specific bacteria.
The significance of the team management in emergency vector control was proposed in the present study by reviewing the earthquake relief work in Liangshui town, Qingchuan county in Sichuan province. The four aspects, including common aspirations, appropriate team establishment, an unobstructed communication platform and outstanding teamwork training, were stressed as the important guarantee for a high?performance team based on concrete examples of team management.
Objective The characteristics of the internal environment of CRH (China Railway High?Speed) trains were analyzed to provide the basis for development of the specialized roach control measure for CRH trains based on the living habits of cockroaches therein. Methods A thorough investigation into the CRH trains of a certain railway bureau was conducted (17 carriages, 230 compartments including the driver’s room) to monitor the cockroach density in the trains. SPSS was used to identify the critical control points for elimination of cockroaches for the CRH trains. Results The infestation rate of adult and nymphal cockroaches in the CRH trains was 19.13%. The highest density of cockroaches was found at the buffet, fresh cabinets and under the seats. Gel baits for cockroach (containing 1% sulfluramid each tablet) were applied for testing; finally, the average cockroach density was less than of one per compartment. Conclusion The cockroach control method suitable for CRH trains was developed based on the living habits and distribution patterns of cockroaches. Experimental results showed significant difference in the control effect between the developed method and the original method (insecticide residual spraying).
