ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
Objective To establish the method for the detection of host odor selection of fleas using the Y-tube olfactometer, and to learn the host selecting behaviors of Ctenocephalides felis felis, Xenopsylla cheopis and Leptopsylla segnis between white rat and white mice, providing evidence for the study of flea host selection and the relationship of “fleas-host/human-diseases”. Methods With X. cheopis used as the test insect and Y-tube olfactometer as the test device, the effect of Y-tube wind speed, the arm-tube position of the Y-tube olfactometer and test room light on the flea host selection behaviors were studied. With this method, the host selection behaviors between rats and mice of C. felis felis, X. cheopis and L. segnis laboratory populations were measured. Results It was found that in the period of detection that lasted for 20 min there was no significant differences in the selection behaviors of X. cheopis when the air flow rate was 0.6-1.5 L/min, neither were the arm-tube position of the Y-tube olfactometer and the changes in light. C. felis felis was found to have significant selectivity for rats by the established method, while X. cheopis and L. segnis had no significantly different behavior response to the rats and mice. Conclusion The host selection behaviors of fleas can be measured with Y-tube olfactometer. Host selection behaviors are helpful in understanding their host specificity and in learning the correlation of “flea-host/human-diseases”.
Objective To evaluate the potential of Aedes aegypti to transmit West Nile virus(WNV) in China. Methods Ae. aegypti was infected orally with WNV and after 12 to 14 days’ incubation allowed to transmit the virus through bite wounds. RT-PCR, virus isolation with C6/36 and indirect immunofluorescence assay were implimented to detect WNV in experimentally infected mosquitoes and Leghorn chicken. Results It was found that the WNV loaded in the susceptible host leghorn was the highest in the 2nd day after infection, indicating that it was the best time for the evaluation of the transmission. Ae. aegypti could be infected by WNV with a susceptibility rate of 63.3%, and transmitted the virus to healthy Leghorn chicken by bite wounds with a transmission rate is 30.0%. Conclusion Ae. aegypti is a potential vector of WNV in some areas such as Hainan province, likely to cause outbreaks of West Nile fever in China in future. Actions are to be taken for the control and prevention of the vecor.
Objective To compare the black box method with the labor hour method in terms of their differences in the surveillance of mosquito density and explore the possibility of substituting black box method for the labor hour method for the surveillance. Methods The differences between the black box method and the labor hour method in terms of their performance in the surveillance of mosquito density and species were compared based on the data from three independent surveillance sites, with the correlation of the two Methods in the surveillance of the species composition ratio, sex ratio and seasonal fluctuation trends examined. Results The Results showed that the density of mosquito by black box method was 1.51 mosquitoes per site, lower than that by labor hour method (3.13 mosquito per box), with a significant difference between them (t＝4.985, P＝0.0025). In terms of the seasonal fluctuation tendency of mosquitoes, similar findings from the two Methods were obtained with good correlation and significant statistical difference (r＝0.8833, P＝0.0084). It was found that the density of female mosquitoes by the labor hour method was 1.88 mosquitoes per site, higher than that by black box method (0.50 mosquito per box) with a significant difference between them (t＝5.043, P＝0.0023). There was no correlation between the fluctuation curves of the two methods(r＝0.4812, P＝0.2743). The species and composition of mosquitoes were also different with the two different methods. The main species collected by the black box method was Culex pipiens pallens(90.6%), followed by Cx.tritaeniorhynchus(4.1%), Aedes albopictus (2.4%) and Armigeres subalbatus(2.9%), with no Anopheles sinensis found. As far as the labor hour method was concerned, Cx. pipiens pallens(42.8%) and Ar. subalbatus (40.3%) were the main species collected, with Cx. tritaeriorhynchus, Ae. albopictus and An. sinensis accounting for 11.7%, 4.7% and 0.5% respectively. In addition, there was a different sex ratio of the mosquitoes collected with the two different methods, with the number of male mosquitoes larger than that of female ones in the surveillance with the black box method, and the opposite being true for the labor hour method. The quantity of female mosquitoes collected by the black box method was close to that by labor hour method, but there was a statistically significant difference (χ2＝146.18, P＜0.001). The quantity of male mosquitoes collected by the black box method was larger than that by the labor hour method with a statistically significant difference (χ2＝513.01, P＜0.0001). Conclusion The black box method, capable of capturing more female than male mosqitoes, is applicable to the surveillance of a variety of mosquito species , but the regularity and standard operating procedure (SOP) of the method as a surveillance tool remains to be studied.
Objective To evaluate the influence of different sugars and vitamins on the oviposition behavior of gravid female Culex pipiens pallens and Aedes albopictus in laboratory, providing theoretical support for the development of a highly effective ovitrap. Methods The oviposition preference of gravid female Cx. pipiens pallens and Ae. albopictus to different concentrations of sugar and vitamin solutions was determined in laboratory. Results It was found that the gravid female Cx. pipiens pallens preferred to lay eggs in glucose solutions of 100 mg/L and of 1000 mg/L and sucrose solution of 1000 mg/L, with no obvious oviposition preference of the gravid female Ae. albopictus to the sugar solutions tested found, compared with the control tap water. Vitamin B1 solutions of 100 mg/L and 10 mg/L and VC solution of 100 mg/L could produce a significant oviposition preference for Cx. pipiens pallens and so could VB1 solution of 10 mg/L for Ae. albopictus. Conclusion Gravid Cx. pipiens pallens and Ae. albopictus have a high oviposition preference for VB1 with gravid Cx. pipiens pallens attracted to glucose as well in terms of the preference.
Objective To investigate the distribution of mosquito vectors of dengue fever in Sichuan province for providing data for the prevention and control of the epidemic. Methods Surveillance on the vector of dengue fever, Aedes albopictus, was conducted all over the province from 2008 to 2009, with the dengue virus isolated and the density of mosquito vectors analyzed. Results Statistics showed that the container index (CI) of 19 surveillance sites was 24.05% with an adult Ae. albopictus density of 5.69 per person per hour. It was seen that waste tyres had a highest CI (48.77%), followed by some special places which had a CI and density of Ae. albopictus of 40.74% and 15.32 per person per hour, respectively. The peak CI appeared in July (30.60%), with the peak density of adult Ae. albopictus observed in August (7.94 per person per hour). It was found that the Ae. albopictus was the predominant species in most surveillance sites, with the composition ratio being between 26.88%-98.37%. There was a regional but not geographical location difference in the density of Ae. albopictus in the 19 surveillance points. No Ae. albopictus was found in the south of Ganzi prefecture. A sample of 4470 adult Ae. albopictus was collected in Longchang county, Neijiang city with no dengue viruses isolated from them. Conclusion There exists an extensive distribution of Ae. albopictus in the Szechwan Basin. An epidemic outbreak may occur once there is a case of dengue fever in the area. So surveillance on dengue needs to be strengthened.
Objective To investigate the population and density of rodents and their dynamics in farmland in the earthquake-stricken area of Beichuan county and the new Beichuan county. Methods The night trapping method was used for the investigation into farmland rodent population dynamics in Beichuan earthquake-stricken area in July, October, 2009 and in January, April, 2010. Results In July, 2009, 44 small mammals were captured, which belonged to 2 families,4 genera and 4 species. The rodent density and sex ratio, the pregnant rate of female rodents and the average number of embryos was 20.66%, 1∶0.87, 50.00% and 3.6, respectively. In October, 2009, 28 individuals were trapped, which belonged to 2 families, 2 genera, 2 species. The population density, the sex ratio, the rate of pregnant female rodents and the average number of embryos were 16.47%, 1 ∶1, 25.00% and 3.0, respectively. In January, 2010, 8 individuals belonging to 2 families, 2 genera and 2 species were captured. The parameters were 4.00％, 1∶0.33, 0 and 0, respectively. In April, 2010, 18 individuals were caught, which belonged to 2 families, 2 genera and 2 species. The parameters were 8.37%, 1∶0.64, 71.43% and 4.0, respectively. Anourosorex squamipes was the dominant species in all the investigation. Conclusion Farmland rodent density in Beichuan county fluctuated with seasons, which may be influenced by changes in seasons and temperature, crop growth status, rodent breeding time and the impact of the massive and disastrous earthquake.
Objective To get an insight into the ecological dynamics of Xenopsylla minax, the main vector of Rhombomys opimus plague for providing data for the prevention and control of the epidemic. Methods Mouse and animal fleas and those in and at the entrances of the holes in the plague surveillance areas of the ports were collected and examined to determine the number of pregnant fleas under microscope, and the dominant flea species collected from the sources month by month in the year were identified and classified with a chart showing the seasonal fluctuation of X. minax. Results It was found that X. minax was not only distributed in the open field and the suburb area, but also in the urban area of the port, accounting for 66.3% of all the fleas collected. It was the main parasitic flea of the R. opimus, and the secondary parasitic flea of many other rodents and variety animals in the area. The peak density of X. minax in mice was observed in April with a flea index of 12.87, and that of free flea in the holes and at the entrances of them in July with a flea index of 1.70. The reproductive period of female X. minax lasted from March to September, with the peak from April to June constituting 68.3% of all the pregnant fleas in the year. Conclusion X. minax is a flea species that can live all the year round in the Chinese frontier port bordering Kazakhstan with multiple hosts and wide distribution. It can be naturally infected with plague bacteria, bite people and suck blood. Good precautions should be taken in the peak periods of mouse fleas and free fleas in and at the entrances of the holes to prevent the plague from occurring among people.
Objective To get an insight into the resistance mechanisms of Musca domestica to beta-cypermethrin so that a theoretical basis was provided for the selection of a rapid and accurate monitoring technique and for the scientific use of insecticides. Methods The glutathione peroxidase(GSH-PX) activities of three strains of M. domestica cultured in laboratory, the beta-cypermethrin resistant strains, the resistance decay strains and the sensitive strains was detected by SDS-PAGE analysis to evaluate the role of the peroxisome in the development of M. domestica resistance. Results It was found that GSH-PX activity of the resistant M. domestica increased significantly with a relative activity of 165.89% in contrast with the activity of the enzyme that decreased to 70.13% in the resistance decay strains. Significant differences were visualized in 6 bands of the electrophoresis pattern of the 3 strains. Conclusion The change in the peroxidase activity in M. domestica strains resistant to beta-cypermethrin may play an important role in the development of M. domestica resistance.
Objective To measure the efficacy of boric acid wood preservatives in the prevention of Coptotermes formosanus (Shiraki) and Reticulitermes speratus (Kolbe) in buildings. Methods A cohort of C. formosanus or R. speratus were subject to timbers or wood blocks treated with 5% or 10% borate preservative by painting or dipping to determine the respective toxicity and residual effect. Results Borate treated wood demonstrated a good resistance effect against C. formosanus and R. speratus, which were dead at both concentrations with either wood treatment approach. C. formosanus were more susceptible to the agent as the subjects demonstrated shorter survival duration. All subjects of C. formosanus died in (12.6±2.4) days and all R. speratus in (16.8±1.7)days as exposed to wood without ageing, both shorter than the time for death of the groups exposed to wood after ageing, (19.1±2.7) days for C. formosanus and (21.8±5.0) days for R. speratus, respectively. The death rate of the control group was lower than 0.1%. C. formosanus was more susceptible to boric acid in view of the resistance effect, as the intactness index of each piece of borate treated wood in that group was higher than 90. The intactness index of wood treated in 5% by painting or 10% agent by either painting or dipping, with or without ageing, remained above 90. In contrast, wood in the control group was seriously damaged with the intactness index as low as 60 and 40, respectively. It was suggested that borate treated wood had satisfyingly stable and long-last toxicity against termites, which was not compromised by ageing. Conclusion Borate wood preservative can be used for wood treatment for effective termite prevention in buildings.
Objective To explore the feasibility of the application of time series model to predicting the malaria incidence in China so as to provide the theoretical basis for the reduction of malaria incidence. Methods An autoregressive integrated seasonal moving average (ARIMA) model was established based on the data on malaria incidences from 2004 to 2009 in China. With the difference method used to smooth the sequence, we determined the order and established the 2010 national malaria incidence forecast model to evaluate the predicting results. Results It was found that there was a year-by-year decrease in the incidence and death rate of malaria from 2004 to 2009, and the incidence fluctuated with seasons with the peak incidence seen from July to October. Seasonal ARIMA model fitted well, and the residual autocorrelation function graph showed that the residuals were white noise sequences, which fitted well with the incidence sequences in the previous periods of time. Further prediction of the incidences in the individual months in 2010 with the model indicated that malaria incidence decreased in the year compared with the previous years. Conclusion The seasonal ARIMA model can be well applied to the fitting of data on malaria incidence with good forecasting, providing a scientific basis for the development of measures for the prevention and control of malaria.
Objective To understand the status of Orientia tsutsugamushi infection in Pinggu district, Beijing. Methods Nested?PCR（nPCR）was employed to amplify and sequence the groEL gene and 56×103 protein of O. tsutsugamushi from 30 samples collected in the district, with indirect immunofluorescence assay (IFA) used for the detection of the specific antibody to O. tsutsugamushi in the serum samples. Results There was a positive rate of 100% in terms of the gene and protein in the 30 blood samples tested with PCR, and 25 of the 28 serum samples that were tested by indirect immunofluorescence assay were found to be positive for the antibody, accounting for 89.3%. There were 3 samples that were positive with long fragment PCR amplification and DNA sequencing revealed that the sequences from all the samples were identical with a homology of 96% with Kawasaki type. Conclusion The existence of scrub typhus in Pinggu district of Beijing was for the first time confirmed from the perspective of molecular epidemiology and seroepidemiology. Our study indicates that physicians need pay attention to scrub typhus in febrile patients living in northern China where scrub typhus was not considered present in the past.
Objective To monitor Borrelia burgdorferi infection and the incidence of Lyme disease and its epidemic trends in the natural foci of Lyme disease in Southern Mountainous Area of Urumqi, providing the basis for the development of strategies for the control and prevention of the disease. Methods The indirect immunofluorescent assay (IFA) and western blot (WB) were used to detect serum IgM and IgG antibodies against B. burgdorferi, with urine samples from 2 patients tested for DNA of B. burgdorferi by PCR. The cases of B. burgdorferi infection and Lyme disease were identified by the clinical features, detailed medical history and physical examination in combination with laboratory findings. Results The average infection rate with B. burgdorferi was 16.14% (36/223), with 27 cases including 6 cases identified during 1999 to 2002 and 21 cases during 2003 to 2006 confirmed the diagnosis of Lyme disease, who manifested multiple organ impact including the cardiovascular system, central nervous system, the skin, the eyes and the joints. And erythema was also seen in 44.44%(12/27) of children infected with B. burgdorferi. Conclusion There are a relatively high rate of infection with B. burgdorferi and typical cases in the pastoral areas and, semi-pastoral and semi-agricultural areas in Southern Mountainous Area of Urumqi. Great importance is to be attached to the control and prevention of the disease.
Objective To investigate and analyze the species, density and seasonal fluctuation of mosquitoes as well as the main mosquito-borne pathogens at Zhejiang port in an effort to provide a scientific basis for the development of effective measures for the control and prevention of the insects and mosquito-borne diseases. Methods Mosquitoes captured by mosquito collection devices were identified and classified. Fluorescence quantitative PCR method was used to detect pathogens carried by mosquitoes, including dengue virus, Japanese encephalitis virus(JEV), West Nile virus(WNV), malaria parasites and other pathogens. Results The mosquitoes captured at Zhejiang port belonged to one family, five genera and twelve species. Culex pipiens pallens or Cx. pipiens quinquefasciatus were found to be dominant species, accounting for 57.87% of the total mosquitoes, followed by Anopheles sinensis, constituting 23.75%. The average density was 0.38/(light·hour) with its peak activity being from June to August. The test Results of dengue virus, JEV, WNV and malaria parasites and other pathogens were negative. Conclusion The dominant species at Zhejiang port are consistent with the data collected locally, with different features seen at each port. There is a potential for outbreak of imported malaria at Zhejiang port, but little possibility of mosquitoes being infected with dengue virus and other pathogens is seen. The lower density of mosquitoes at Taizhou and Shengsi ports may be associated with the special environment at Taizhou port and the endemic island climate at Shengsi port. Mosquito density at the airports is significantly higher than that at the harbor, which is probably related to the unique environment and higher population density there.
Objective The nucleoprotein structural gene of the Rabies virus NB0901 strain isolated in Ningbo city in 2009 was amplified and sequenced by RT-PCR to get an insight into the epidemiological characteristics of rabies in this area. Methods The N gene sequence of the NB0901 strain was obtained using RT-PCR and sequence analysis. The homology of the gene with vaccine strains, 3aG and CNT-1, was analyzed at the nucleotide and amino acid level, respectively, followed by phylogenetic analysis. Results The homology between the NB0901 strain and the vaccine strains ranged from 86.6%-90.1% to 95.5%-98.8%, respectively, at the level of nucleotide and amino acids. By comparison with the vaccine strains, mutations were found at NⅠ and NⅡ antigen epitopes of the NB0901 strain. Epitopes of the T helper cells were identical between the NB0901 strains and CNT-1 strains, whereas those in 3aG had remarkably mutated, suggesting that the NB0901 strain belonged to subtype A of groupⅠof Rabies virus. Conclusion Though NB0901 and the current vaccine strains belonged to the same group, this strain was partly different from the latter. Based on the analysis at the amino acid level, CNT-1 strains would be more effective in protecting infection of this strain than 3aG strains.
Objective To get an insight into the carriage status and epidemic characteristics of Bartonella in rodents in Zhejiang province for providing baseline data for the development of measures for the control and prevention of Bartonella infection. Methods DNA was extracted from the livers and spleens of mice and the beta-subunit-encoding gene (rpoB) of Bartonella was selected for PCR amplification, the positive products of which were sequenced and phylogeneticaly analyzed. Results One of 101 rodents captured in Panan county of Jinhua city in Zhejiang was positive for the rpoB gene of Bartonella with the isolation rate of Bartonella in Rattus tanezumi being 4.3％. Phylogenetic analysis showed that the isolated strain was of the same evolutionary branch as B. grahamii (GenBank accession No. AB426694.1) with a bootstrap value of 96%. Conclusion There exists Bartonella infection in rodents in Zhejiang province with R. tanezumi as its possible host. The isolated strain belongs to B. grahamii.
A new species of Culicoides was described during the identification specimens of bloodsucking midges from Xunke ports, Heilongjiang province, C. xunkeensis sp. nov. The new species is somewhat allied to C. corniculus Liu et Chu, 1981 and C. koreensis Arnaud, 1956 in the wing spots, but they are distinctly different in the shapes of aedeagus and parameres of male genitalia. The type specimen is deposited in the Entomology Collection Gallery of Heilongjiang Entry-Exit Inspection and Quarantine Bureau of the P. R. China, Haerbin 150001, China.
The calculation procedure of KT50 of pesticides was conducted with SPSS 15.0, with a full explanation of the main outputs and detailed discussion of the issues that needs to be taken seriously in designing the experiment and processing the data.
Objective To collect the data on mosquitoes intercepted at Shanghai port. Methods Mosquitoes were identified morphologically. Results It was found that there were 30 species (7 genera) of mosquitoes intercepted at Shanghai port, which were from wide geographical sources, with Europe and America being the major ones, accounting for 80.0% of all the intercepted mosquitoes. The findings showed that 18 of the 30 species were newly intercepted at Shanghai port, with 6 species identified as vectors for human disease transmission. Conclusion There exists a high risk for disease transmission by mosquitoes intercepted at Shanghai port, therefore targeted surveillance and quarantine inspection of mosquitoes at Shanghai port is to be strengthened to manage the risk of mosquito-borne diseases.
Objective To get an insight into the dynamics of mosquitoes in the process of the hydraulic cascade development in the Yichang section of the Three Gorges Area, providing important background information for medical assessment of the environment for large-scale water control project. Methods The data on mosquitoes in this area recorded since 1959 with those from 1971 to 2009 collected through investigation were studied and analyzed. The density of mosquitoes was surveyed with the labor-hour method. Results There was an overall downward trend in the density of mosquitoes in the Yichang section of the Three Gorges reservoir area in different periods with a higher density in barns than in houses. The mosquito density during 1971 to 1980 reached the highest value (239.0 per house/hour) compared with the density in the periods before and after the time. From 2001 to 2009, when the second and third stage construction of the Three Gorges Project was completed, the density fell to historic lows (75.2 per house/hour). There were great changes in the composition of mosquito species in both the barns and the houses, which was related to the alteration of the environment where mosquitoes bred, and explained the epidemic features of the vector-borne diseases. Conclusion Currently the density of mosquitoes in the Yichang section of the Three Gorges reservoir area has fallen to historic lows with no significant fluctuations seen in the incidence of the related diseases in the area. The hydropower projects do not show a significant impact on them.
Objective To explore the reproductive capacity of Oncomelania snails in the environment in Qingpu district. Methods Soils that were taken by environmental Methods from 10 sampling sites in all the ten towns of Qingpu district served as the test group, with soil samples taken in the same way from Songjiang district and Jinshan district where O. snails appeared in recent years used as the control group. All these samples were randomized as the experimental fields. O.snails marked by different colors were divided into 12 groups, 25 males and 25 females for each group. The O. snails were also randomized to the fields to see whether the second birth of snails would appear and their survival status over the winter. Results It was on May 22nd, 2008 that the O. snails were stocked and the second generation was first found 147 days later, with the second generation of O. snails appearing in every field of the experimental base before May 17th, 2009. The average monthly temperature for snails to reproduce or incubate was between 27.1 ℃ to 34.3 ℃, with the value being between 3.2 ℃ to 9.8 ℃ for the nails to do the same things in Spring. Statistical analysis by the paired t-test showed that there was no significant difference (t＝0.17, P＝0.87) in the average pH values of the soils before and after the experiment, which were 5.5±0.7 versus 5.4±1.0. Conclusion O. snails are able reproduce in Qingpu district with the ability to survive over winters, relatively low temperature needed in spring for them to reproduce.
Objective To investigate the community structure of gamasid mites in a plague area of Dingbian county for further revelation of the role of these species in transmitting and preserving the plague bacillus. Methods The mites were collected from rodent bodies and nests, fixed in Hoyer’s medium and identified under the microscope. Results A total of 463 gamasid mites under 6 species, 5 genera and 3 families were collected. The dominant species included Haemogamasus kitanoi, Haemolaelaps glasgowi and Eulaelaps cricetuli, accounting for 40.6%, 33.0% and 24.8%, respectively, followed by a small amount of Macrocheles matrius, Macrocheles decoloratus and Laelaps algericus. Eight hundred fifty-nine rodents were captured and 135 nests were investigated. The dominant host mammal was Meriones unguiculatus, accounting for 90.9% of the total captives. The mite-carrying rate was 7.3% in M. unguiculatus and 23.7% of all nests. Most of the collected mites were female. Conclusion The community structure of gamasid mites is simple in this area with only a few species parasitic on the dominant host rodents. The dominant gamasid mites found on M. unguiculatus included H. kitanoi, H. glasgowi and E. cricetuli.
Objective To determine the indoor effects of the auto-sensing acousto-optical rodent repeller placed on a ship rope for further research and application. Methods Food baits were placed on a common ship rope extending diagonally indoor to attract starving rats. As the subject rodents approached the baits, the autosensing acousto-optical rodent repeller was triggered right before the immediate contact. The whole course of rodent movements and triggered repelling performance was monitored and recorded. Results The repeller was sensitive to any mobile subject at a distance of 50 cm. Once automatically triggered, it forced the starving rats to abandon the food close by and escape instantly (within one second). Conclusion The auto-sensing acousto-optical rodent repeller installed on a common ship rope indoor has sensitive, strong and fast repelling effects on rodents in its sensible area with repeatable and reliable effects.
Objective To investigate the density and distribution of Aedes aegypti and Ae. albopictus with seasons at the Beihai international port. Methods The labor hour method was used for surveillance of adult mosquitoes, with the index number method, the egg apparatus method, and the 100 ml counting method employed for larva surveillance. Results A total of 697 adult Aedes were captured in Beihai port with 317 adult Aedes sampled in Tieshangang port. All the adult Aedes and larvas collected in the two ports were identified as Ae. albopictus, and the average density of adult Aedes in Beihai port and Tieshangang port was 17.2 and 7.4 per labor hour respectively. The value of HI, CI, and BI of larva Aedes was 4.0% and 13.0%，19.2% and 27.2%，and 5.0 and 17.2, with an ovitrap index of 12.0% and 23.2%, and a larvas Aedes density of 2.0 larvae/100 ml and 2.8 larvae/100 ml at the two ports respectively. Conclusion There exist high density of adult Aedes and index of larvae Aedes in the two ports, suggesting that there is a high potential risk for dengue prevalence. The basic information about species of Aedes, the density and the larvae, etc. in the ports should be taken into account to better develop further control and preventive measures againstAe. aegypti and Ae. albopictus, and dengue epidemic.
Objective To determine the habits and distribution patterns of cockroaches on different types of passenger trains for effective cockroach prevention and control life in these environments. Methods The number of cockroaches crawling out or knocked off in 10 minutes after pesticide spray was recorded to calculate the infestation rate and average density. Results The average infestation rate was 27.7%, as shown in descending order as follows: Series 22 (45.5%)＞25B (37.7%)＞25G (24.2%)＞SYZ25B (16.7%)＞25K (7.4%) and CA (90.0%)＞YZ (32.3%)＞YW (17.1%)＞RW (5.0%). The average density was 2.51 roach per compartment, as shown in descending order as follows: Series 22 (4.58)＞25B (3.75)＞25G (2.01)＞SYZ25B (1.17)＞25K (0.43) and CA (6.35)＞YZ (3.51)＞YW (1.30)＞RW (0.15). The perching positions were mainly the four corners of a compartment, the crew room, the storage room, the electric motor of refrigerator, ventilations beneath the kitchen and the distribution room. Cockroaches were also seen at the light boxes in the washrooms and ventilation holes at the compartment roof. Conclusion The passenger trains are heavily infested with cockroaches. Cockroaches have been found at the light boxes in washrooms, ventilation holes at the roof, middle bunks and other higher positions, varying on different types of trains. Those positions and other hiding places such as the distribution room should be specifically investigated during cockroach control. Pesticide spray and gel baits are effective control measures.
Objective To analyze the serological Results derived from suspected Lyme Disease patients for efficient diagnosis and treatment. Methods Using the indirect immunofluorescence assay(IFA), enzyme-linked immune sorbent assay (ELISA) and western blot(WB), suspected Lyme Disease patients were tested for Borrelia burgdorferi IgM and IgG antibodies. A comprehensive analysis was conducted in combination with clinical cases. Results IgG antibodies were positive as shown by IFA, ELISA and WB methods. The titer of IgG antibodies was up to 1∶128 as shown in IFA and two protein bands, P83 and P39, were present in WB. IgM antibodies were negative as shown in the three test approaches. Conclusion Based on the typical clinical course and positive laboratory Results of the patients, the diagnosis of Lyme disease can be confirmed.
Objective To determine the epidemiological characteristics of hemorrhagic fever with renal syndrome (HFRS) in Longyou county based on analysis of surveillance Results for the deployment of specific control measures. Methods HFRS surveillance data from 2004 to 2010 were analyzed in combination with field investigation and laboratory tests to reveal the virus distribution in human and host animals. Results The average annual incidence rate was 0.78/105 from 2004 to 2010 in Longyou county. Most patients were at the age from 40 to 50 years, accounting for 63.64%. Farmers accounted for 77.27% of all patients. The ratio of male to female was 2.14∶1. Summer and winter were two incidence peak periods in a year. The onset cases were observed in most of towns and villages. The highest incidence was found in Longnan mountain area. The diagnosis accuracy was 82.35%. The virus-carrying rate was 2.95% in rodents with Rattus tanezumi being the predominant host animal indoor (80.28%) and Apodemus agrarians being the predominant host outdoor (89.29%). The seroprevalence of HFRS antibodies in rats was 4.81%. Conclusion A declining trend of the HFRS incidence is shown in Longyou county, though the epidemiological characteristics of this disease remain unchanged. The surveillance Results have shown that Longyou county is a mixed HFRS epidemic area dominated by the Apodemus type.
Objective To investigate the status quo of the pest control operations (PCO) and service quality in Ningbo for promoting the quality and efficacy of vector control. Methods The annual accounting statements of PCO companies were examined, the expenditures on vector control on field and in township (county or street) randomly checked and the management of service quality evaluated. Results There were 40 enterprise members and 704 managers and operators in Ningbo PCO Association. The total business turnover was 33.33 million and 41.19 million Yuan in 2008 and 2009, respectively. Increase of business turnover in pharmaceutical and medical apparatus, specialized industries and general entities was observed in varying degrees. The number of townships (counties) adopting market-oriented operations increased by 20 with a turnover spike of 4.92 million Yuan. 98.40% of the annual statements were consistent with the actual flow and questionnaires showed a degree of satisfaction of 96.75%. The financial contribution of townships averaged 219 300 Yuan, slightly lower than the average funds as shown by the annual statements. In view of the service management system established and implemented in PCO companies, the inspection Results of organizations at all levels and the degree of satisfaction in the public, the vector control effect in this area was satisfying. Conclusion Thanks to the government’s advocate and support of marketized operation and effective service quality management, Ningbo PCO maintains a good momentum of growth.
Mosquitoes, due to their special behavior, physiology and close relationship with human beings, act as important vectors of some human diseases. The resistance of mosquitoes to insecticides is considered to be a recent evolutionary adaptation to environmental changes in response to the use of chemical insecticides. In this review we summarize the resistance monitor data on organophosphate and pyrethroid resistance in seven mosquito species in China (Culex pipiens complex, Anopheles sinensis, Cx. tritaeniorhynchus, An. minimus, An. lesteri, Aedes albopictus and Ae. aegypti) since 1990s. The documents showed that these mosquitoes in most regions of China have evolved to be resistant at various levels to organophosphate and pyrethroid insecticides, even though some of them still keep sensitive to the two kinds of insecticides.
Single nucleotide polymorphisms (SNPs) mainly refer to the polymorphism of DNA sequence caused by a single nucleotide mutation, including the synonymous SNPs and non-synonymous SNPs. With the rapid development of sequencing technology, a large number of bacterial genome sequences are available. So, it’s possible to identify potential SNPs sites by sequencing technology and bioinformatics methods. Also, SNPs, because of their own characteristics, have been widely used as a new molecular marker in bacterial genotyping, evolution and epidemiology research. In this paper, advances in the research on the genome-wide search of SNPs sites and analysis of the Yersinia pestis microevolution based on SNPs data are reviewed.
Dengue fever (DF), widely prevalent in the tropic and subtropic regions, is an important infectious disease transmitted by mosquito biting. With the global climatic warming and rapid development of the tourism and transport industry, the geographic distribution of Aedes aegypti as the major vector of DF virus has changed in China, with the variation of its ecological behaviors occurring in response to the measures long taken for mosquito control. Researches on the relationship between Aedes aegypti and the spreading of dengue virus have showed that both the horizontal and the vertical transmissions are the important patterns for Aedes aegypti to save dengue virus. Aedes aegypti is highly susceptible to dengue virus with a high rate of virus infection. This paper reviews the geographic distribution, ecological behaviors and relationship of Aedes aegypti with DF spreading in China.
Malaria (Plasmodium spp.) causes nearly one million deaths annually and with the increase in mosquito resistance to drugs the existing anti-malaria strategies are inadequate in terms of the control efficiency. The introduction of genes that impair Plasmodium development into mosquito population is a new strategy for malaria control. The article reviews some recent advances in the research of transgenic mosquitoes, gene regulation mechanisms and the way by which the transgenic mosquitoes play their role in the control of malaria.
