| Background By biting and sucking blood,mosquitoes can induce immune responses and cause allergic reactions in the bite site,which will affect the normal production and life of human beings.More seriously,in this process,they will spread a variety of diseases that threaten human health and life.Due to the influences of globalization,climate change,urbanization and other factors,mosquitoes' distribution and density have changed,which indirectly affect the epidemic risk of mosquito-borne diseases.The global incidence of mosquito-borne diseases is high,and the number of imported mosquito-borne diseases from endemic areas is also increasing year by year.In recent years,through investigating the occurrence and prevalence of mosquito-borne diseases,it is found that such occurrence and prevalence will be directly affected by the mosquito population density which is closely related to environmental changes.Wanzhou District of Chongqing is located in the core area of the three Gorges Reservoir Region,where all types of water bodies are important places for breeding mosquitoes.Since the construction of the Three Gorges Project,water storage has led to changes of the original large and medium-sized water bodies in Wanzhou,which has a series of impacts on the mosquitoes' ecology.Therefore,it will be very important to know the changing law of mosquito population density and explore the influencing factors of mosquito population density for the prevention and control of mosquito-borne diseases in Wanzhou section of the Three Gorges Reservoir Region.Objective 1.To preliminarily analyze and evaluate the impact of TGP construction on mosquito ecology and identify influencing factors or potential risks based on the investigation of mosquito population distribution and density change from the construction period to the initial storage period of the TGP in the affected Regions.2.To explore the relationship between the mosquitos,mosquito-borne infectious diseases and meteorological influence factors,put forward the measures to improve the population health and the rationalization of the follow-up studies,thus to provide the basis for completion acceptance of environmental protection of TGP.Methods 1.Wanzhou section of the Three Gorges Reservoir Region was selected as the survey point of mosquito population and density.During 1999-2014(from the construction period to the initial storage period of TGP),the mosquito population and density were investigated by adopting mosquito catch method from May to September.The numbers and species of the mosquitos were recorded and descriptive analyses were performed.2.Meteorological data of Wanzhou District,including monthly precipitation,monthly average air pressure,monthly average air temperature,monthly average relative humidity and monthly cumulative sunshine hours and so on,were obtained from Chongqing meteorological bureau,followed by descriptive analyses.3.The incidence data of mosquito-borne diseases(including dengue fever,malaria,and epidemic encephalitis B)in Wanzhou District from 2005 to 2014 were collected from the Report Management System of Disease Monitoring Information managed by China CDC,followed by descriptive analyses.4.As the mosquito density and some meteorological data were not normally distributed by Shapiro-Wilk test,Spearman correlation analysis was carried out by SPSS version 19.0.Results 1.The main mosquito species,from high to low densities,were Armigeres subbalbeatus,Anopheles sinensis,Cx.pipiens pallens/ Culex quinquefasciatus and Culex tritaeniorhynchus in Wanzhou section from 1999 to 2014.The total mosquito density was 142.38 per room per hour,244.47 in livestock boxes,and 60.30 in human houses.The adult mosquito density began to rise rapidly from June,peaked in July,and decreased in August or September.The mosquito density variation curves were almost the same between livestock boxes and human houses.2.From 1999 to 2014 in Wanzhou section of the Three Gorges Reservoir Region,the average annual rainfall was 1276.48 mm,the annual mean air pressure was 992.06 hPa,the annual average temperature was 18.67 ?,the annual average relative humidity was 77.42%,and the annual average sunshine hours was 1197.31 hours.3.From 2005 to 2014 in Wanzhou section,the main mosquito-borne diseases were epidemic encephalitis B,malaria and dengue fever,among which malaria and dengue were imported cases.The incidence of epidemic encephalitis B in males was significantly higher than that in females,with a sex ratio of 1.93:1.In terms of age,the incidence was mainly in the group of 1 ? 4 years old,especially the 4 year old,accounting for 58.54% of the total incidence.The onset time was mainly from July to August,accounting for 96.34% of the total incidence.4.The mosquito density was negatively correlated with the monthly mean air pressure of the same month and the month before,and was positively correlated with average monthly temperature and monthly cumulative sunshine hours in same month,and monthly mean relative humidity in the month before.Conclusion The incidence peak of mosquito-borne diseases was consistent with the mosquito density peak.Atmospheric pressure,air temperature,sunshine hours,relative humidity and other meteorological factors were closely related to mosquito density.Geographical changes affected mosquito densities indirectly by changing climate.It's necessary to continue related monitoring to further understand mosquitos carrying pathogens,so as to accurately determine the risk of outbreak of mosquito-borne diseases. |
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