Objective To investigate the population distribution and density changes of mouse-like rodents in the Chongqing section of the Three Gorges Reservoir Area, China, and analyze the ecological influence of the Three Gorges Project on rodents, for an understanding of the potential spreading risk of rodent-borne diseases. Methods The surveillance data of mouse-like rodents in the Chongqing section of the Three Gorges Reservoir Area from 2005 to 2018 were collected for descriptive and linear regression analyses by Excel 2010 and SPSS 25.0 softwares, respectively. Results Thirteen species of mouse-like rodents were found in the Chongqing section of the Three Gorges Reservoir Area, with a total density of 1.68%. In residential areas, the density was 2.01%, and the dominant species were Rattus tanezumi,R. norvegicus, and Mus musculus. In cropland, the density was 1.37%, and the dominant species were Insectivora, R. tanezumi, and R. norvegicus. The density of mouse-like rodents in cropland showed a decreasing trend along the flow of the Yangtze river. The total density tended to increase with years, and reached its peak in March throughout the year. The density of R. tanezumi increased significantly with years, especially in residential areas. Conclusion The population distribution and density of mouse-like rodents have changed significantly after the completion of the Three Gorges Reservoir, and there is a risk of occurrence and spread of rodent-borne diseases. Surveillance and control of mouse-like rodents should be strengthened.

Objective To understand the distribution of rodents, dynamics of rodent density and composition in hydro-fluctuation area of Three Gorges Reservoir after experimental storage, and provide evidence for the risk prediction and control of rodent-borne diseases. Methods Four surveillance sites were set in upper, middle and down reaches of the Three Gorges Reservoir and surveillance were carried out twice after water drainage and before water storage every year. The small mammal density and the species composition in different regions, altitude and periods were analyzed. Results During 2010-2014, a total of 116 small mammals were captured and the average capture rate was 1.10% and on the decline overall. The captured small mammals were classified into six species. Apodemus agrarius was the predominant species accounting for 46.55% and Anourosorex squamipes was next with 25.86%. The average capture rate after water drainage (1.23%) was higher than that before water storage (0.90%). All captured small mammals distributed in all three altitude and the composition decreased from high to low latitude. The predominant species was different in three altitude. The predominant species in 166-175 m altitude was A. squamipes accounting for 44.45%, followed by Rattus tanezumi (18.52% ); In 145-155 m and 156-165 m altitude, Ap. agrarius was predominant species accounting for 84.00% and 72.97%, respectively. Conclusion The average capture rate was low and there was various species of rodent in hydro-fluctuation area. The density and species composition of small mammals varies with different regions, altitude and monitoring time. The host animals of hemorrhagic fever of renal syndrome, Leptospinosis and commensal rodent plague may be of risks in hydro-fluctuation area of Three Gorges Reservoir. It should be strengthened to monitor the host animals and take the corresponding control measures in the area based on the risk assessment.

Objective To investigate the change of the characteristics of rodents before and after the water storage in the Three Gorges Reservoir. Methods Mouse traps and cages were used to detect the density of rodents in different periods of the Water Storage. Results The indoor density of rodents before water storage was 4.14%. While it was 1.67% after water storage; the outdoor density of rodents before water storage was 4.29%, and it was 1.44% after water storage. The former was higher. The indoors densities of Rattus tanezumi in recent two years were much higher than before, it was 0.84% in 2011 and was 0.77% in 2012. Conclusion The densities of rodents significantly decreased after the second water storage in the Three Gorges Reservoir. But the indoors densities of R. tanezumi in recent two years were much higher than before. Continuous monitoring of rodent populations is warranted.

Objective To investigate the species composition and population density of mosquitoes before impoundment and after recession in the fluctuating zones of the Three Gorges Reservoir region and to provide a basis for surveillance of mosquito vector and mosquito-borne diseases. Methods Four surveillance sites were established in the typical fluctuating zones at upper, middle, and lower streams of the Three Gorges Reservoir region. For each surveillance site, 3 lamp trapping cages were placed at each of the three different altitudes (10 m altitude difference). The surveillance was carried out before impoundment and after recession in 2010. Results In 2010, a total of 101 mosquitoes were captured with 90 lamp-times, which belonged to 4 species: Culex tritaeniorhynchus, which accounted for 21.78% (n＝22); Anopheles sinensis, which accounted for 16.83% (n＝17); Cx. pipiens, which accounted for 16.83% (n＝17); Armigeres subalbatus, which accounted for 6.93% (n＝7); other species, which accounted for 37.63% (n＝38). Conclusion The fluctuating zones of the Three Gorges Reservoir region provide breeding sites for mosquitoes. Mosquito density is low in these areas, and shows a decreasing trend with increasing altitude. Vector of Japanese encephalitis, Cx. tritaeniorhynchus, and malaria vector, An. sinensis, exist in these areas.

Objective To investigate the species composition and density of the murine-like animals and their parasitical fleas in Chongqing Reservoir Area of the Three Gorges and provide a scientific basis for preventing and controlling the diseases transmitted by the murine - like animals and fleas. Methods The night trap method was used to investigate the species composition and density of the murine-like animals. Live murine-like animals were captured by cage-trap and anaesthetized for collecting the parasitic fleas to investigate the flea species and the infection rate and index. Results The average density of the murine-like animals was 1.58% with a density of 1.56% in the rooms from 2009 to 2010, which was a little lower than that in outdoors(1.60%). A total of 11 species, 2315 murine-like animals belonging to 2 orders and 2 families were captured, of which Anourosorex squamipes, Mus musculus and Rattus norvegicus were the dominant species with the constituent ratio being 38.75%, 25.14% and 19.27%, respectively. The average rate of the murine-like animals infected with fleas and the total flea index were 6.74% and 0.29, respectively. Five species of parasitic fleas were collected including Leptopsylla segnis(79.16%), Xenopsylla cheopis(1.08%), Monopsyllus anisus(2.54%), Palaeopsylla remota(8.90%)and Ctenocephalides felis(8.32%). Conclusion There exist important reservoir host of plague, Leptospinosis and hemorrhagic fever with renal syndrome and X. cheopis which is an important vector of plague in the Three Gorges Reservoir. There are abundant species of the murine - like animals with relatively low density, low flea infection rate and low total flea index.

Objective To understand the species composition and quantitative distribution of the dominant host animals and plague vector fleas, and the infections of host animals with Yersinia pestis in Wanzhou and Fuling sections of the Three Gorges Reservoir Area to determine whether there existed plague foci or not. Methods Rodents captured by cages and fleas collected with sticky papers, were identified with the flea-carrying rate and flea index calculated. The plague F1 antibody from host animals was detected with IHA. Results (1)Host animals: one hundred and seventy rodents were captured in Wanzhou with a rodent density of 3.20% and 303 rodents in Fuling with a density of 5.95%.(2)Flea index: one hundred fifty-one fleas were caught in Wanzhou with a flea-carrying rate of 22.94% on rodents, the total flea index being 0.888. Sixty-four fleas were caught in Fuling with a flea- carrying rate of 7.59%, the total flea index being 0.211.(3)The free flea index: three thousand sticky papers were placed and 6 fleas were captured in Wanzhou with a total flea index of 0.002. No fleas were captured in Fuling with the same method.(4)The plague serological examination: in Wanzhou and Fuling sections, no plague F1 antibody was detected. Conclusion Wanzhou and Fuling sections are not plague foci where no plague has occurred, but based on the information of geographical landscape, host animals, vector insects and epidemiological investigation, it is likely that the plague epidemic may occur in the sections.

Objective To provide the basis for early detection and control of plague in the Three Gorges Reservoir through monitoring of the host animals, insects and plagues in this region. Methods Night traps were used to measure the rat density. Live rodents were captured using cage traps to collect serum samples for detection of plague F1 antibody and determination of parasitic fleas on the rodent body. Animals which died of unknown causes were recorded, and plague monitoring was carried out. Results The average rodent density was 1.49% in Chongqing area of the Three Gorges Reservoir from 2007 to 2008. The indoor density was 1.50%, the outdoor 1.48%. Rattus norvegicus, Mus musculus, R. tanezumi and Anourosorex squamipes were the dominant species. The average flea-carrying rate was 4.03%, and the total flea index was 0.13. The parasitic fleas found on those rats included Monopsyllus anisus (0.12%), Leptopsylla segnis (77.88%), Palaeopsylla remota (14.39%) and Xenopsylla cheopis (7.61%). For the 6549 surveyed live rats, the serological test was all negative for plague. There was neither a large number of dead animals of unexplained causes nor plague cases. Conclusion Plague was not found in Chongqing area of the Three Gorges Reservoir, though the vectors and host animals exist.

【Abstract】 Objective Know the dynamic change of mosquito population constitution and its density and its seasonal fluctuation in Three Gorges Reservoir area. Methods The mosquitoes were captured by direct current electric mosquito-catching trap at the fixed time and places, and then identified and counted. Results The dominant species of mosquitoes were Armigeres subalbatus, Culex pipiens quinqusfasciatus, Anopheles sinensis, Cx.tritaeniorhynchus and Cx.pipiens pallens in the Three Gorges Reservoir area. The density of mosquito in room was higher than outside. Conclusion The density of mosquito tended to decline from 1997 to 2007, and mosquito monitoring should be strengthened.

Objective To explore main plague hosts, vectors and plague foci in the second phase water line of the Three Gorges project in Chongqing, and provide scientific basis for plague early warning and control. Methods Investigate the density of rat-shape animals inside and outside of home. The rat-shape animals were anaesthetized to investigate the varieties of parasitical fleas and the infected rate after captured by cage-trap. Identify the captured rat-shape animals and know their population and distribution. Plague F1 antibody was tested in serum samples separated from the blood of anaesthetized rat-shape animals. Search for the dead animals without specific death causes and monitor the plague epidemic situation, and acquire the information about the natural foci and epidemic situation. Results 3 order, 8 families and 27 species of rat-shape animals were found in this area. Among them, Rattus norvegicus, Mus musculus, Rattus flavipectus and Anourosorex squamipes were the dominant species. The average density of rat-shape animals was 1.57%, and the density of them was 1.64% in the room that was a little higher than that of outside(1.51%). 10 340 serum samples of rat-shape animals were tested and no positive results were obtained. 6 species of parasitical fleas such as Xenopsylla cheopis, Monopsyllus anisus, Leptopsylla segnis, Ctenocephalides felis, Palaeopsylla remota and Neopsylla specialis were found. The average rate of rat-shape animals infected with fleas and the total flea index were 6.51% and 0.15, respectively. The results of epidemiology survey and epidemic situation monitoring indicated that there were no plague in mice or human population in the region. Conclusion No plague was found so far in the Three Gorges Reservoir region in Chongqing, but R.flavipectus and X.cheopis were widely distributed in this region. Once the infection sources were introduced, the outbreak of plague would be possible. So there was potential risk for plague in this region, we should pay more attention to it.

Objective To monitor rodents and vector fleas in Three Gorges,to find plague earlier and take prevention and control measures immediately. Methods Use clamp-trap method to monitor rodent density in residential areas and out of side. Use cage-trap method to capture live rodents to extract serum for detecting F1 antibody. Hocus the living rodents and collect their parasitical fleas. Results 87 327 clamps were placed in 2005,of which 84 146 clamps were valid,1278 rodents were obtained,the total rodents density was 1.52%,and the density in room was 1.67%,which was higher than that of outside (1.41%). The dection of all serum for F1 antibody was negative. 326 of 4114 rodents were found infecting with flea. Total 853 fleas were collected,which needed further identification. The rate of rodents with fleas was 7.92%,total index of flea was 0.207. Conclusion There has been no plague in Three Gorges in Chongqing area.