ISSN 1003-8280 CN 10-1522/R 中国疾病预防控制中心 主办
When the vector-borne diseases break out, natural disaster occurs or disease vectors overflow, vector surveillance and control in emergencies is the significant strategy and approach in response to these events. This paper mainly studied and stated the purpose and purport of vector surveillance and control in emergencies, the current achievements and problems, the groundwork and the key points, the current challenges and future development mechanism vector surveillance and control in emergencies.
Objective To evaluate the inhibitory effects of tick management with avermectin on the prevalence of Xinjiang hemorrhagic fever(XHF), i.e. Crimean-Congo hemorrhagic fever(CCHFV), in livestocks. Methods Comparative experimental study on the efficacy of tick management with avermectin was implemented in goats in the epidemic foci in the Tarim Basin. Results It was found that the tick infestation rate in the experimental group was 55.0% with a tick index of 1.0 after oral the administration of Avermectin, a tick management drug, for the goats and the rate and the index in the control group were 100% and 11.2, respectively, with the 2 parameters 45% and 10.2 respectively lower in the experimental group than in the control group. After six months’ experiment, the positive rate of antibody to XHF in the experimental group was 22.4%, consistent with the the rate before experiment(23.7%) but significantly lower than that in the control group(45.9%). Conclusion Avermectin for goats in the epidemic foci of XHF contributes to the prevention of tick infestation and the prevalence of the epidemic in livestocks.
Objective To study the subspecies of Francisella tularensis in China and the genetic relationships among the various strains of them. Methods Ten strains of F. tularensis from North China were subject to PCR using two specific primers C1C4 and RD1. Their subspecies were identified based on the length of the amplification products. At the same time, PCR on three specific genes was performed using fopA, tul4 and 16S rRNA primers, followed by sequencing. Based on the three specific genes, phylogenetic analysis was conducted using MEGA 4 software to involve the 10 strains of F. tularensis and the three strains of F. tularensis type B and one strain of subsp. novicida published on the NCBI website. Results The 10 strains of F. tularensis were identified as type B based on the PCR results using two specific primers C1C4 and RD1. According to the phylogenetic tree structured by MEGA 4, the 10 strains of F. tularensis from China can be classified into two types: B1 type, including 410108, 410109 and 410111, and B2 type including the other seven strains. In contrast, the three foreign strains were of type B3. Conclusion The F. tularensis isolated in North China may be predominated by type B. As for the origin of F. tularensis type B, the F. tularensis in China has probably emerged earlier than those in Europe and America. Phylogenetic analysis based on the three specific genes can be used as a reliable genotyping tool for F. tularensis.
Objective To test the pathogenicity of 5 strains of entomopathogenic fungi to Culex pipiens pallens larvae and select the highly pathogenic strain against Cx. pipiens pallens, providing a scientific basis for the prevention and control of the insect. Methods The five fungal strains that are commonly used in biological control were used for the detection of the cumulative motality rates of Cx. pipiens pallens larvae caused by different concentrations of fungal spore suspension, with the median lethal concentration (LC50) values worked out. Results Evaluated based on the growth rate and sporulation, all of the five strains showed different degrees of pathogenicity against Cx. pipiens pallens larvae. At 10 days, the five strains GIM3.428, GIM3.45,GIM3.431, GIM3.95 and GIM3.436 resulted in a cumulative mortality rate of 100%, 82%, 79%, 73% and 57%, with the LC50 being 2.98×102、1.41×103、1.26×104、1.02×104、2.07×105 conidia/ml, respectively. Conclusion The fungal strain GIM3.428, which is of the highest pathogenicity against Cx. pipiens pallens larvae, can be used for the control of the insect.
Objective To screen highly attractive formulations to Musca domestica under simulated field conditions in order to determine the optimal bait that can be commercialized for fly density monitoring. Methods Two different bait formulations were used on fly traps in a simulated field to compare their attraction effects. Results After two rounds of screening, SA-8 baits (50 g stale fish gel, 100 g brown sugar and 100 g water) were remarkably superior over other compounds considering the capture rate and cost-effectiveness; its capture rate (36.95%) was higher than that of sugar-vinegar baits (12.64%) with significant difference (χ2＝214.35, P＜0.01). Conclusion SA-8 could be subject to the field test as a candidate bait for further verification of its attraction effect on M. domestica and other fly species.
Objective To observe the effect of adult cold storage on the longevity and reproductive capacity of female Nasonia vitripennis. Methods The female N. vitripennis emerged on different days were cold stored at 15 ℃ for different period. Their longevity, parasitic capacity and reproductive capacity were then measured. Results The longevity of female N. vitripennis was extended after cold storage at adult stage. However, as the cold storage time prolonged, the parasitic and reproductive capacities were compromised. At a cold storage time for less than 12 d, the impact on these capacities of female N. vitripennis was not remarkable. In contrast, after cold storage of over 12 d, the egg production and parasitic capacities declined linearly. After cold stored for 24 d, the parasitic ratio of Boettcherisca peregrina by N. vitripennis reduced to 35% from 85% before cold storage and the average emerging parasitoid progeny to 6 from 33 per fly pupa. However, the female adult rate and the body length of the progeny were not affected. Conclusion Adult cold storage extends the longevity of female N. vitripennis at the cost of reproductive capability.
Objective To determine the number of species, diversity of endemic species and faunal characteristics of the Calyptratae fauna in Luyashan Nature Reserve of Shanxi province. Methods The biological diversity in the region was studied based on entomological classification principles and related approaches. Results A total of 243 species, 96 genus and 10 families of Calyptratae were found in the nature reserve, among which Muscidae share the highest diversity, accounting for 42.86% and 39.51% of the known Calyptratae genera and species in the region, respectively. In Luyashan Nature Reserve, there were 102 species of Palearctic out of 243 known Muscidae, accounting for 41.98% of the overall species in this region, followed by 58 Palearctic and Oriental species, accounting for 23.87%. These species, together with the Palaearctic and the other commonly distributed, accounted for 96.30% of the overall species. In addition, nine endemic species were found, making up 3.70% of the known species in the area. Conclusion In Luyashan Nature Reserve of Shanxi province, the Calyptratae fauna has high species diversity and is characterized by Palearctic elements and significant regional features.
Objective To determine the anti-fertility effect of curcumol baits on Lasiopodomys brandti. Methods The experimental group was fed with baits of 3 doses, 0.1%, 0.2% and 0.4%, respectively, while the control group received nontoxic blanks. The voles freely consumed the baits for 3 consecutive weeks before gross examination, in which the morphology of genital organs was observed, and the organ coefficient calculated. The sperm quality was measured for male animals. Results Curcumol baits were effective anti-fertility agents against both male and female L. brandti. As for female voles, abnormal ovarian development was observed with impaired follicular maturation in the 0.2% and 0.4% dose groups; increased organ coefficient for the uterus was present in each dose group along with uterine edema, the extent of which was positively correlated with the dose administration. As for male animals, intoxicated individuals had lowered sperm motility, concentration and viability in addition to increased risk of sperm malformation, where the most common abnormality was acrosomal loss; their epididymal organ coefficient also declined to a degree positively correlated with the dose. Curcumol did not affect the individual development of either gender. Conclusion While curcumol baits had anti-fertility effects on L. brandti, the duration and recoverability of drug effect should be further studied.
Objective To measure the impact of avermectin on the cellular immunity, humoral immunity and nonspecific immunity of Kunming mice. Methods The subject mice were assigned to the experimental groups to receive avermectin at doses of 20, 10, 5 mg/kg for 28 days and a blank control group. The cellular immunity was evaluated in terms of T lymphocyte proliferation and delayed type hypersensitivity (DTH), the humoral immunity estimated with plaque forming cell assay (PFC) and half hemolysis value method (HC50), and the nonspecific immunity measured based on peritoneal macrophages phagocytosis for chicken red blood cells, carbon clearance test and NK cell activity. Results At a dose of 20 mg/kg, the T lymphocyte proliferation was 0.76 (in contrast to 0.86 in the negative control), the half hemolysis value 128.45 (versus 140.96 in the negative control), and the PFC 89.21×106 (versus 113.33×106). In the 20 mg/kg and 10 mg/kg medication groups, the carbon clearance indices were 5.59 and 5.61 (versus 7.96), and the peritoneal macrophage phagocytosis levels for chicken red blood cells were 0.86 and 0.90 (versus 1.05). Reduction was observed in all of the above function indicators compared to the control group, with significant difference (P＜0.01). Conclusion Avermectin inhibits the celluar immunity, humoral immunity and nonspecific immunity of Kunming mice.
Objective To investigate the faunal characteristics of rodent community in Haidong area of Qinghai province. Methods The night trap method was used to determine the quantity of rodent populations at different habitats in this area as the basis for ecological analysis. Results A total of 427 rodents were captured in Haidong area, which belonged to 15 species, 6 families and 2 orders, including 82 rodents of 7 species in mixed conifer forests with a capture rate of 3.90%; 112 rodents of 6 species in forest edge scrubs with a capture rate of 4.53%; 77 rodents of 7 species in alpine shrubs with a capture rate of 3.35%; 95 rodents of 7 species in alpine grasslands with a capture rate of 2.94%; and 61 rodents of 9 species in residential farmlands with a capture rate of 2.60%. The highest biomass (35.95) of rodent community was observed in alpine grasslands, followed by that in forest edge scrubs (34.70) and lowest in alpine shrubs (21.59). The fatness of Mus musculus and Rattus norvegicus peaked in residential farmlands at 5.18 and 4.05, respectively; the fatness of Cricetulus longicaudatus peaked in alpine grasslands at 3.80; and the fatness of Apodemus peninsulae peaked in forest edge scrubs at 2.97. The biomass and fatness of one species varied and diversified in characteristics at different habitats. Conclusion The faunal composition of rodent populations is complicated in Haidong area of Qinghai province. Upcoming anti-rodent work should be focused on reducing the density of predominant species and preventing the occurrence of rodent infestation.
Objective To determine the current resistance of Culex tritaeniorhynchus, vector of Japanese encephalitis (JE), to commonly used pesticides in Suzhou city, Jiangsu province. Methods Using the dipping method, the median lethal concentration (LC50) values of deltamethrin, betacypermethrin, permethrin, biothrin, dichlorovos and propoxur were measured for the field population of Cx. tritaeniorhynchus in Suzhou city. Results The LC50 values of deltamethrin, betacypermethrin, permethrin, biothrin, dichlorovos and propoxur for Cx. tritaeniorhynchus were 0.0424, 0.1137, 0.2659, 0.6698, 2.4691 and 7.7017 mg/L, respectively. Intermediately resistant to biothrin, the strain was highly resistant to the other five agents with resistance ratios of more than 50, even 100, to the three pyrethroids. Conclusion In view of the low or higher resistance of Cx. tritaeniorhynchus to multiple pesticides, environmental and biological strategies in conjunction with auxiliary chemical approaches should be deployed for better control of this vector. Administration of pesticides and rational agricultural planning should be carried out based on the big picture. In the event of skyrocketing mosquito density or occurrence of JE epidemic, pesticides should be scientifically distributed and chemical control approaches intensified.
Objective To measure the resistance of Rattus tanezumi to the 1st generation agent after their exposure to the 2nd generation anticoagulant rodenticides for several years in Leizhou city, Guangdong province. Methods Rats captured in Leizhou suburb were raised indoor for days. Eligible rodents were subject to non-selective feeding test using 0.005% warfarin baits. The relationship between the mortality and intakes was recorded and analyzed. Results Among 36 eligible rodents, 32 died from the consumption of agents. The development of warfarin resistance in the subjects, 11.11%, was close to the critical level of development of population resistance. There was no significant difference in the lethal dose and lethal time between male and female rats (df＝30, Pd＝0.987, Pt＝0.971). The average volume of toxicant intake was (115.71±53.84) mg/kg for dead rats, with the average lethal time of (7.2±2.4) d. Conclusion The changing trends of rodent sensitivity to anticoagulant rodenticides should be regularly monitored during the application of these agents for economically optimizing the use of drugs.
Objective To explore the frontier quarantine strategies for prevention and control of exotic vectors. Methods Exotic vectors first intercepted at Ningbo port from 2004 to 2009 were analyzed along with the case study of hazards brought by exotic vectors. Results With many years of strict frontier quarantine on international sailing ships, containers and cargos, 39 exotic vectors of 3 species, Supella supellectilium, Cochliomyia macellaria and Panchlora nivea were captured for the first time from 10 batches, as well as 9 species from 12 batches, which were sparsely distributed in a handful of provinces other than Zhejiang province. Hence, hazardous exotic vectors were effectively prevented from invading or spreading in China. Conclusion Frontier quarantine is irreplaceably essential to preventing the import of exotic hazardous vectors.
Objective To develop an indicator-based early warning system for Lyme disease outbreaks. Methods The preliminary framework and indicators were formulated based on literature review and expert consensus. The early warning indicators and respective weights were determined using Delphi expert consultation, and the impacts of different indicators were measured by weighting coefficients. Results An indicator-based early warning system for Lyme disease was formed using six primary warning indicators, including the host and vector, high-risk population, meteorological factors, social environment, previous prevalence and index cases, as well as 14 secondary indicators. Conclusion The indicator-based early warning system for Lyme disease in China has been basically established. Local early-warning proposals should be based on the indicator system and tailored to the actual situations.
Objective To establish subtracted cDNA libraries using the suppression subtractive hybridization (SSH) technique based on the livers of New Zealand white rabbits infected with Schistosoma japonicum before and after praziquantel treatment, providing the basis for screening the drug-response molecular target during the therapy. Methods New Zealand white rabbits infected with S. japonicum were assigned to two groups to receive praziquantel medication or blank, respectively. The SSH technique was conducted to build the forward and reverse subtracted cDNA libraries using the PCR-Select cDNA Subtraction kit. The differentially expressed ESTs were screened and positive clones were isolated from the libraries for bioinformatic analysis．Results Thirty-nine positive clones were isolated from two subtracted cDNA libraries, including 22 from the forward library and 17 from the reverse library. The analysis revealed that the ESTs were mainly responsible for coding enzymes and proteins associated with protein synthesis and degradation. Conclusion The subtracted cDNA libraries before and after praziquantel treatment for S. japonicum were successfully constructed, laying a solid foundation for further research into the molecular mechanisms of this medication therapy.
Objective To get an insight into the composition, distribution and HV-carrying condition of host animals in the national monitoring sites of hemorrhagic fever with renal syndrome (HFRS) in Hebei province, providing scientific evidence for the prevention and control of the epidemic. Methods Investigations of host animals were carried out in spring and autumn, respectively, in the four national monitoring sites, with the trap-night method used for the detection of the density of rats and immunofluorescence technique for that of the pulmonary virus antigen of the pests. Results It was found that from 2005 to 2009 the density of rats in the populated area in the monitoring sites fluctuated between 0.63% and 2.50%, and the density of rats in the open country between 0.37% to 0.71%, with a higher density of the pests in the populated area than in the open country (χ2＝177.05, P＜0.01). The virus-carrying rate of rats in the populated area was 1.76% with the rate being 0.84% in the field. In terms of the composition of the host animals, Rattus norvegicus was the dominant host (77.39%), followed by Tscherskia triton (12.42%) and Mus musculus (8.70%). In the 12 positive rodents, 10 were R. norvegicus (83.33%), 1 was M. musculus (8.33%)， 1 was T. triton(8.33%). Conclusion
Objective To provide the basis for the prediction, early warning and development of control strategies of dengue epidemic by analyzing the dengue surveillance data in three national surveillance spots in Guangxi from 2005 to 2008. Methods Descriptive epidemiological analysis was conduced based on the dengue fever data reported through the China Information System for Disease Control and Prevention and the surveillance results of designated spots from 2005 to 2008. Results From 2005 to 2008, two imported cases of dengue fever were reported in Guangxi while no case observed in the three national surveillance spots. The predominant species of vector was Aedes albopictus, though no Ae. aegypti were detected. The breteau index(BI) was above 5, the security level, in all surveillance spots most of the year, particularly in Fangchenggang and Qinzhou city, where the indices stayed above 20 most of the time. The Aedes larval density peaked from June to August, with temporary containers being the major positive culprits. Neither dengue virus nucleic acids, nor viral isolates, were detected from 1208 Ae. albopictus. Conclusion With the presence of dengue-carrying vectors, Guangxi has faced potential risks of dengue epidemic. Therefore, the surveillance system and public health education should be strengthened to curb the BI under 20.
Objective To produce a list of rodents at bilateral ports along the China-Russia border in Heilongjiang province. Methods A China-Russia cooperative team conducted a background survey on rodents at six ports in China and three ports in Russia along the Amur River border from 2006 to 2009. Results Rodents of 1 order, 3 families, 11 genera and 13 species were found at the 6 ports in China, while 1 order, 3 families, 8 genera and 10 species were found at the Russian ports. Conclusion In view of the increasing global threat of epidemic diseases, the list of rodents may provide the basic information for public health and the prevention and control of related rodent-borne diseases.
Objective To explore the new, environment-friendly and pollution-free technology for rural rodent monitoring and control. Methods The trap barrier system (TBS) technology was applied to capture rural rodents from October 2007 to April 2008. The crop growth period and the species, age, sex, pregnancy, litter size and other characteristics of rodents were recorded. The wheat yield was measured and rodent control effect evaluated during the harvest season. Results Eighty rodents were captured using the TBS technology, including 23 Anourosorex squamipes and 57 rodents such as Apodemus agrarius and Micromys minutus. The resulting rodent control effect was up to 61.3%, and the wheat yield increased by 11.7% as compared to the control farmland. Conclusion The TBS technology, an effective tool for farmland rodent monitoring and control, has overcome the flaws in the Methods of bamboo tube bait stations and rodent traps, and may achieve green and hazard-free management of farmland rodents. This technology can be promoted and applied at larger scale.
Objective To determine the susceptibility of Lasiopodomys brandti to bromadiolone for providing the base data on its resistance to bromadiolone. Methods The males and females were separated and divided into groups at random. No-choice feeding tests were carried out with 0.0005％ bromadiolone bait at five different feeding days. The relationship between feeding days and their corrresponding mortality rates was analyzed by Bliss software. Results There was no significant difference (Pb＞0.05, PLFP50＞0.05) between male and female L. brandti in terms of their susceptibility to bromadiolone, with the LFP50 and LFP99 of bromadiolone to L. brandti being 2.20(1.88-2.58) days and 6.71(4.48-10.05) days respectively. Conclusion Based on the criterion recommended by WHO, LFP99 value of bromadiolone to susceptible rodents is used as the resistance diagnose criterion. L. brandti is considered to be resistant when it is still alive after being fed on the bait containing 0.0005％ bromadiolone for 10 days.
Objective To investigate the distribution, seasonal prevalence, diurnal rhythm, bitting and breeding of Culex pipiens quinquefasciatus and Cx. pipiens pallens in Pudong International Airport. Methods Sample collection was done by means of bednet trap, lamp baited trap, human baited trap, larvae dipping and labor hour method. Results It was found that Cx. pipiens quinquefasciatus and Cx. pipiens pallens were the dominant species of mosquitoes in Pudong International Airport, which were harmful to human health from April to November. The findings from the lamp baited trap showed a slope-shaped curve for the seasonal fluctuation of the insects, beginning in April, peaking from May to June and declining gradually from October and disappearing at the end of November. The bednet trap revealed that the insects were active predominantly in the evening and at night, with peak activity seen 1-4 h after the sunset and little movement during the day. The human baited trap indicated that the peak time of bitting was at 21:00 o’clock, with a maximum frequency of 42 times/15 min). The number of mosquitos that entered each room was highest from 19:00 to 21:00 with the highest burglary rate being 9 mosquitos per 15 min. The larvae were mainly breeding in still sewage or clean water in ponds, pools, bottomlands, ditches and containers, etc. Conclusion Cx. pipiens quinquefasciatus and Cx. pipiens pallens are common human-biting species in Pudong International Airport. The data on the seasonal prevalence, diurnal rhythm, bitting and breeding of Cx. pipiens quinquefasciatus and Cx. pipiens pallens contribute to the prevention and control of the insects and related vector-borne diseases.
Objective To determine the insecticidal resistance of Musca domestica in urban areas of Liaoning in order to provide the basis for scientific administration of insecticides in fly control．Methods Topical application of insecticides solved in acetone was made to the mesonotum of M. domestica. Results Different degrees of resistance of M. domestica to four commonly used insecticides were observed in Fushun, Benxi, Liaoyang, Anshan city of Liaoning. The resistance to deltamethrin was the highest, with the average resistance coefficient of 61.60, followed by the resistance to propoxur with an average resistance coefficient of 22.65. The average resistance coefficients to alpha-cypermethrin and dichlorvos were 8.71 and 4.72, respectively. Conclusion Insecticides should be applied scientifically to effectively curb the increase in insecticidal resistance of M. domestica.
Objective To get insight into the species composition of midges in the Meiling scenic area, providing a scientific base for the control and prevention of blood-sucking midges in the area. Methods The light trap and insect net capture Methods were employed to collect midges in different habitats in the scenic area, and slide specimen were used for the identification of the species in the laboratory. Results A total of 29 species of midges belonging to 5 genera were collected, of which 13 species (11 species belonging to genus Culicoides, 2 species to genus Lasiohel) belonging to two genera, were identified as the blood-sucking midges, with 16 species of 3 genera including 5 species of Dasyhelea, 8 species of Forcipomyia and 3 species of Atrichopogon identified as non-blood-sucking midges. 23 species of midges were found to be new in Nanchang. Conclusion Researches on midges, especially on the blood-sucking midges are not well develpoed and efforts remain to be made to deepen the area in well-rounded manners.
Objective To analyze and sort the fleas in the plague foci of Spermophilus alaschanicus in the Ganning loess plateau for providing the epidemiological data on fleas for the control and prevention of plague. Methods The Methods of descriptive epidemiology was used for the integrated analysis of the composition of fleas based on the data sorted according to the Siphonaptera, Class Insecta, the Chinese Fauna. Results A total of 62 species of fleas (subspecies), which belonged to 26 genera and 7 families, were found in the plague foci of S. alaschanicus. There were 6 species (subspecies) of fleas that were widely distributed in the foci of all the administrative divisions (countries) of the region; There were some specific flea species in some each administrative divisions, there being 4 species specific to Haiyuan county, 1 species to Xiji, 15 to Huining county and 3 to Pingchuan district. Conclusion Citellophilus tesquorum mongolicus was the most common and stable species with a high detection rate, being dorminant in the bodies of mice, burrows and nests. So it is the major vector of the host S. alaschanicus in the foci with other rodents and birds also serving as its hosts. In particular, the exchange of fleas parasitic on birds is of great importance in the transmission of plague, which is worth exploring in terms of the epidemiology of animal plague.
Objective To study the epidemiological charactristics of hemorrhagic fever with renal syndrome(HFRS) in Tiantai county for the development of the strategies specific to the prevention and control of the epidemic. Methods Epidemiological investigation into the epidemic situation among human population was conducted by means of the indirect immunofluorescence assay (IFA) for the detection of serum antibody in patients and healthy population. The virus-carrying state of the host animals was determined by Hantaan virus antigen detection with the direct immunofluorescence assay. Results A total of 181 HFRS cases was reported with an average annual incidence rate of 6.39/105 in Tiantai county from 2005-2009. There was an incidence ratio of 2.42∶1 for male and female patients, with peasants affected predominantly accounting for 86.74%. The total density of rodents was 4.87% with an average indoor rodent density of 2.10% and an outdoor one of 5.76%. The average virus-carrying rate of rodents was 7.48% and the serum positive rate of patients was 77.70%. Conclusion Tiantai is a mixed HFRS epidemic area, with the Apodemus-type dominant. Greater efforts need to be made in the surveillance and prevention of the epidemic.
Objective To get an insight into the current epidemiological characteristics of malaria in Cixi from 2001 to 2009 for the development of malaria control strategies. Methods Malaria surveillance data in Cixi from 2001 to 2009 were analyzed by retrospective epidemiological approaches. Results A total of 135 malaria cases were reported from 2001 to 2009 in the city. One of them was a local resident returning home with imported infection, while all of the others were imported cases. The annual average incidence of the floating population was 2.17/105. Most of them were the migrant workers at age 20-39 years and 99.26% cases were attributable to vivax malaria. Conclusion In the past 9 years, Cixi has made significant achievements in malaria control. However, in view of the occasional imported cases in the floating population, great importance should still be attached to malaria prevention and control in the city.
Objective To understand the epidemiological characteristics of Japanese encephalitis (JE) and to provide the basis for early detection and control. Methods Confirmed cases, suspicious cases, host animals, mosquito vectors and healthy population were monitored according to the National Japanese Encephalitis Monitoring Program. Results From 2005 to 2008, 137 suspected JE cases and 10 laboratory-confirmed cases were reported in the county with an incidence of 0.52/105. No death case was found. All cases were children under 7 years of age and clustered in July. One patent had complete JE vaccination history. The mosquito density began to surge from June, with Culex tritaeniorhynchus being the predominant species accounting for 43.5% of all captured vectors in this area. Two strains of JE virus were isolated from mosquitoes captured in 2007. The time of onset in human was consistent with the spike in mosquito density. The overall infection rate in the host animal swine was 67.4%, and the peak of infection in these animals appeared one month earlier than in human. Conclusion Natural factors in favor of JE epidemics and prevalence of this disease were found in Xianju county. Filling the immunization gap is the most effective way to prevent and reduce the occurrence of this disease. JE monitoring is helpful for early detection and epidemic control.
Mosquitoes, due to their special behaviors, physiological characteristics and close relationship with human life, have been important vectors of some human diseases. The resistance of mosquitoes to insecticides is considered to be an evolutionary adaptation to environmental changes in response to applications of chemical insecticides. In this review we summarize the findings from the investigations implimented since 1990s on the resistance of the seven mosquito species in China (Culex pipiens complex, Anopheles sinensis, Cx. tritaeniorhynchus, An. minimus, An. lesteri, Aedes albopictus and Aedes aegypti) to organochlorines and carbamates. It is found that there are 7 species of vector mosquitoes that have a high level of resistance to DDT. So far only the resistance of Cx. pipiens to BHC and acetophenate has been documented and a low resistance of the vector to the insectisides reported. Investigations on the resistance of the insects to carbamates have been conducted mainly through evaluating the resistance of Cx. pipiens complex to suncide and bassa, with a low resistance found.
In this review the effects of habitat on the flea community and life history are analyzed to throw light upon the relationship between habitat and flea community and life history, providing information for the prevention of flea from spreading pathogenic microorganisms. The habitat of flea consists of the host and its environment. The composition and abundance of a flea community in a certain habitat is influenced not only by the species and relative abundance of the host, but also by the characteristics of its habitat itself. The abundance and reproductive modes of flea community show a significant variation with seasons where there are distinct seasonal characteristics. Different ecological systems with different landscapes have an influence on the diversity of host animals, resulting in a difference in the composition and density of fleas. It is of important implications to learn the relationship between the environment and the dynamics of the flea community and its life history for the control of flea population, interruption of transmission and prevention of the speading of pathogenic microorganisms.
Small mammals are known to have a wide range of diversity and distribution as well as a smaller transference. The composition of different types and the characteristics of spatial distribution are closely related to the geographical environment, climatic conditions, ecological adaptive capacity and diseases. Therefore, the fauna and diversity of small mammals have great significance in the investigation and study. The geographical distribution trends of Yunnan take on a gradual decrease in the altitude from the north to the south，where the complex exotic nature and the geographical conditions have given birth to the unique fauna and flora. There are abundant species of mammals in Yunnan with about 300 species of mammals, including many rare species, which take up 47% of the number of known species in China (about 642 species). At present, there are 201 species, 82 genera, 19 families, 6 orders of small mammals in Yunnan. In this paper, the current classification, fauna and biodiversity of small mammals in Yunnan as well as the relationship between environmental factors and diseases are presented，and perspective on the future developmental trends and challenges in terms of study on small mammals are discussed.
Fertility control technology plays an important role in rodent population management. It can reduce the rodent population directly and indirectly without intensifying ecosystem fluctuations. At present, domestic and international fertility control technologies are focused mainly on chemical sterilization, endocrine perturbation and immunocontraception. This study reviews the evolution of rodent fertility control technology at home and abroad, analyzes the underlying physiological and the ecological mechanisms and gives an overview of the practical prospects.
