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Objective To investigate the geographic landscape features in Yulong plague natural focus.Methods Four altitudinal gradients (2 400-,2 600-,2 800-,≥3 000 m) were selected as study objects in Yulong plague natural focus from December 2015 to November 2016 to collect and analyze geographic landscape factors (topography and terrain,climate,water areas,vegetation and soil) based on the literatures about this plague focus.Results Yulong plague natural focus was an area with mid-mountain and subalpine topography in northwestern Yunnan Province,and its terrain had the character of lower in the southeast and higher in the northwest.This area belonged to plateau warm temperate monsoon climate of low latitude with an average month temperature 13.6 ℃ from 2005-2016,month air relative humidity averaged 59.4％,and rainfall averaged 884.5 mm a year,which concentrated mostly from June to September.About 98.1％ of the water area in Yulong County was controlled by Chin-sha River.The vegetation and soil were characterized by vertical distribution along with altitude gradients obviously.Conclusion The unique geographical landscape of the plague natural focus in Yulong County is one of important factors affecting the occurrence and epidemic of the plague.
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Objective To analyze and evaluate the application of indirect hemagglutination test (IHA) method in the epidemic area of Meriones unguiculatus in Inner Mongolia.Methods The plague monitoring summary and epidemic analysis reports of each year in Inner Mongolia from 1996 to 2016 were collected.The serum results of the IHA method were analyzed,including the time,region and the distribution of host animals.Results From 1996 to 2016,a total of 38 096 serum samples were detected from various host animals,and 172 positive samples were detected,with a positive rate of 0.45％.In the 21 years,except 2001 and 2015,the occurrence and prevalence of plague were judged by the IHA method for the remaining 19 years.There were 10 counties detected positive sera by IHA method;the positive results were detected by IHA method in 6 kinds of host animals,including 5 rodents and 1 carnivorous,and the positive rate of Rhombomys opimus was up to 6.17％ (91/1 475),the highest titer of the seropositive host animals was as high as 1:10 240.Conclusions The IHA method is easy to operate and economical.It plays a huge role in the timely detection of the epidemic in systematic monitoring of the Meriones unguiculatus in Inner Mongolia.
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Yellow fever(YF) is a natural focal disease transmitted by infected mosquitoes,which had caused epidemic in some areas of Europe and America port city in the history,bringing great disaster to human society.Since 40s of last century,a series of derivative strain of 17D vaccines,providing lifelong protection,had been vaccinated a large population who are trave ling to or living in areas at risk for YF,which avoid the outbreak of the disease,appearing quiet state.Since the beginning of 1990s,the disease had outbreak successively in Africa,tropical American areas and its nations.The mortality was even more higher than Ebola happened in 3 countries in West Africa between 2014 and 2015.In 2016-2017the large outbreak in Angola,Congo and Brazil,has claimed thousands of lives.Yellow fever has never occurred in Asia until the introduction of 11 cases by jet travel from Angola to China,which attracted the attention of Chinese government.Yellow fever elimination initiative strategic plan for 2017 2026 was launched by WHO,mainly based on that 17D vaccine which is safe and effective to control the spread of this disease.The measures of controlling mosquitoes and vaccination programs,in particular putting great expectations for the latter,are the main measures for prevention the disease and achievement the goal of WHO elimination strategic plan.But strong guarantees of related countries and abiding by the provisions of the global quarantine regulations are also important.Therefore,this article reviews the historical and the recent epidemic outbreaks of yellow fever,vaccination and other prevention measures,hoping that the WHO elimination of the yellow fever epidemic strategy will achieve successfully in 2026.
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Objective To analyze the incidence trends and epidemiological characteristics of natural focus and vector borne infectious diseases in Zibo City between 2004 and 2015,and to provide evidence for control and prevention of the diseases.Method Surveillance data of natural focus and vector borne infectious diseases in Zibo City between 2004 and 2015 from the National Disease Reporting Information System were analyzed via descriptive epidemiological methods.Results A total of 10 natural foci and vector borne infectious diseases and 3 287 cases including 55 death cases were reported in Zibo City from 2004 to 2015.The average annual incidence was 6.24/100 000 and the case fatality rate was 1.67％ (55/3 287).The incidence rate increased in recent years after the lowest rate in 2009 (2.83/100 000),and the rate in 2015 was 8.83/100 000.The top three diseases with higher incidence were hemorrhagic fever with renal syndrome (3.44/100 000),brucellosis (1.48/100 000) and tsutsugamushi fever (0.53/100 000).The top three high-prevalence areas with higher incidence were Yiyuan County (13.22/100 000),Zichuan District (9.73/100 000) and Boshan District (6.13/100 000).The cases mainly occurred from March to May and September,October,which accounting for 27.47％ (903/3 287) and 24.64％ (810/3 287),respectively of the total.The 40-59 year-oldage group was the highest,accounting for 48.13％ (1 582/3 287)of the total.And 75.48％ (2 481/3 287) of reported cases were farmers.Conclusions The overall incidence of the natural focus and vector borne infectious diseases in Zibo City has a annual increasing trend in recent years,while the incidence of brucellosis and tsutsugamushi fever have continued to rise since 2004.These diseases have showed a significant seasonal distribution and population distribution.It is necessary to conduct targeted prevention and control strategies.
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Objective To investigate the species composition and quantitative dynamic state of rodent and parasitic flea in Huairou District of Beijing City,and to carry out serologic monitoring of animal plague.Methods Rodent density was investigated at different habitats in eight villages and towns between 2009 and 2011.Serum samples from captured rodents were detected by indirect hemagglutination test,and genotypes of collected parasitic fleas were identified.Results A total of 709 rodents which belong to eight different kinds were captured with a rodent density of 2.52％ (83/3 300),and Rattus niviventer and Apodemus peninsulae were dominant species,acounted for 46.4％ (329/709) and 18.1％(128/709),respctively.Five hundred and sixty-three serum samples of rodents were tested by plague indirect hemagglutination,and all of them were plague antibody negative.Two hundred fleas were checked with a flea infected rate of 29.63％ (48/162),and a flea index of 1.23; Paraceras crispus and Leptopsylla pavlovskii were dominant flea species,a total of 30 and 27,respectively.Conclusion Some environment conditions are suitable for rodents survival,even though there is no sign of animal plague epidemic.
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Objective Throush identify biochemical characteristics and virulence factors of 2 strains suspected Yersinia pestis(Y.pestis)isolated from the dead Marmota himalayana(M.himalayana)to confirm the nature epidemic focus in Dege County,Sichuan Province.Methods Y.pestis was analyzed by specific staining and shape,culturing characteristics,splitting-test by bacteriophage,test of biochemical characteristics and glycolysis ability,virulence factors,virulence,nutritional requirement,plasmid,genetic test and genetic type. Results The tested strains were Gram staining bacilus.The main biochemical characteristics were Arabinose(+)、 Rhamnose(-),Maltose(+),Melibiose(-),Glycerol(+),Denitrification(+).The virulence factors with FI+.VW+, Pgm+,Pst I+;and with the common 6.0×106,45.0×106,65.0×106 plasmids,also with the virulence-relative plasmid gene.Both their absolutely lethal dose(LD100)in mice were 50 bacteria.The nutritional requirement appeared which were depended on Phenylalanine and Methionine.With the Genomovar 5 genotype characteristics of M.himalayana plague foci of Qinghai-Tibet plateau.The difference between tested strains and Yersinia pseudotubercuosis on the 3 different culture medium was obvious.The tested strains had a Y.pestis' specific 3a fragment,Pst I and FI-Ag,at 22 ℃,the strains could be split by bacteriophage completely.Conclusions According to the diagnostic criteria of plague in China,the 2 suspected strains isolated from Dege County,Sichuan Province ale confirmed as Y.pestis.both with powerful virulenceand with the characteristics of the Y.pestis of M.himahtyana in Qinghai-Tibet plateau plague natural focus.