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Objective:To analyze the dynamics of plague epidemic in Spermophilus alaschanicus plague foci of Gansu Province from 1962 to 2018, and to provide evidence for plague control and prevention. Methods:The data of Spermophilus alaschanicus plague in Gansu Province from 1962 to 2018 were collected and organized from epidemic surveillance and epidemic summary. The method of descriptive epidemiology was used to analyze plague, including population (regional distribution, time distribution) and animal (geographic distribution, infected animals and vectors) epidemiology. Results:There was only one case of human plague in the Spermophilus alaschanicus plague foci of Gansu Province from 1962 to 2018. The total incidence of the disease was 26 cases, 11 cases died, the incidence rate was 29.89% (26/87), and the mortality was 42.31% (11/26). The cases were mainly distributed in Liuzhai Township and Xinyuan Township of Huining County. The outbreak occurred from July to August. Plague bacteria were isolated from the plague foci of Gansu Province during two peak epidemics of the plague among animals from 1962 to 2018. The bacteria detection area was located in 2 rural areas that were the northern area of Liuzhai in Huining County, and the neighboring Zhongtian and Fuxing in Pingchuan District. Five places were determined to be the animal epidemic sites. The endemic species were Spermophilus alaschanicus and Vulpescorsac, and the vector species were Citellophilus tesquorus mongolicus and Neopsylla abagaitui. The epidemic time of animal plague was from April to August. Totally 115 positive serum F1 antibodies were obtained. Among them, 92 positive serum samples were detected in Huining County and 23 in Pingchuan District. The positive blood coagulation sites were distributed in 11 villages, 5 towns of 2 counties (districts). The surveillance results showed that 30 species of animals belonging to 5 orders, 11 families, 5 subfamilies, and 21 genera were found in the foci, most of them were Spermophilus alaschanicus, which accounting for 69.1% (2 464/3 567) of the total species of rodents in the past years. A total of 12 482.9 hm 2 were investigated by sampling method, and 9 709 Spermophilus alaschanicus were captured, with an average density of 0.78/hm 2. Conclusions:The plague is intermittently prevalent in Gansu's Spermophilus alaschanicus plague foci. So the prevention and control strategies should be adjusted in time according to the changes. In residential areas, we should take the initiative to strengthen the monitoring of rat situation and the publicity and education of human plague prevention knowledge.
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Objective:To analyse the effects of meteorological factors on plague epidemic in Himalayana marmot plague natural foci in Subei and Sunan counties of Gansu Province. Methods:The surveillance data of plague from 1973 to 2016 in Himalayan marmot foci of Subei and Sunan counties (from Gansu Provincial Center for Disease Control and Prevention) and the meteorological factors (rainfall, temperature, relative humidity) of current, preceding first, second and third years (the first, second and third years before the reference year, from China Meteorological Data Sharing Service System) were collected. In order to build generalized additive model (GAM), the positive rate of plague was used as dependent variable while meteorological factors of the current, preceding first, second and third years were used as independent variables. The influence of meteorological factors on plague was quantitatively analyzed by using R2.3.2 software. Results:In 2006 - 2016, compared with 1974 - 1983, the average temperature in Subei rose by 0.99 ℃, the average relative humidity rose by 3.55%RH, and the average rainfall rose by 12.16 mm; in Sunan County, the average temperature rose by 1.00 ℃, the average relative humidity rose by 2.01%RH, and the average rainfall rose by 14.60 mm. From 1973 to 2016, 11 cases of human plague with 7 cases of dead (12 cases of attack) occurred in the investigated district. The average rainfall of the preceding third year of Subei rose every 1.00 mm within a certain range, the animal plague occurred rose by 0.40%. The average relative humidity of preceding second year of Subei rose every 1.00%RH within a certain range, animal plague occurred rose by 11.66%. The average rainfall of the preceding first year of Sunan rose every 1.00 mm within a certain range, the animal plague occurred rose by 1.32%. The average relative humidity of preceding third year of Sunan rose every 1.00%RH within a certain range, animal plague occurred rose by 11.96%. The average temperature of the preceding second year of Subei, Sunan rose every 1.00 ℃ within a certain range, animal plague rose 73.17%, 70.18%, respectively.Conclusions:The occurrence and prevalence of plague in Himalayana marmot are closely related to meteorological factors, and the temperature within a certain range (but not continuously) not only promotes the epidemic of plague, but also has a lag effect. In addition, the effects of different types of climate in the same foci on the prevalence of animal plague vary.
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Objective To explore the effects of meteorological factors on population densities of the host and the prevalence of animal plague in the natural plague foci of Spermophilus alaschanicus.Methods The surveillance data of seroprevalence rate in natural plague foci of Spermophilus alaschanicus of Gansu Province in current year,one previous year (relative to current year as a reference),as well as two and three previous years’ meteorological data such as average annual rainfall,temperature,relative humidity were collected from 1962 to 2014.SAS 9.3 software was used for correlation and regression analysis of the influencing meteorological factors on the density of Spermophilus alaschanicus and prevalence of animal plague;generalized additive model (GAM) was used for quantitative study of meteorological factors on density of Spermophilus alaschanicus;logistic regression analysis was used to study the effect of meteorological factors on prevalence of Spermophilus alaschanicus plague.Results Serum positive rate of Spermophilus alaschanicus was positively correlated with average annual rainfall of current and previous one year,and with relative humidity of current year (r =0.279,0.341,0.654,P ＜ 0.05);serum positive rate was negatively correlated with average annual temperature of current and preceding first,second and third years (r =-0.360,-0.339,-0.273,-0.323,P ＜ 0.05).The average annual rainfall of preceding second and third years was significantly associated with the densities of Spermophilus alaschanicus by GAM parameter estimation (t =2.88,2.42,P ＜ 0.05).The average annual rainfall of preceding second and third years was significantly associated with the densities of Spermophilus alaschanicus by GAM nonparameter estimation (x2=31.580,13.428,P ＜ 0.05),but the effect was nonlinear.Multivariate logistic regression analysis showed that average annual rainfall of preceding first year [odds ratio (OR) =2.475,95％ confidence interval (C/):1.175-5.213] was risk factor for the prevalence of the animal plague in the natural plague foci of Spermophilus alaschanicus.Conclusions Rainfall is risk factor for the prevalence of the animal plague in the natural plague foci of Spermophilus alaschanicus.There is a lag effect of rainfall on the numbers of hosts and the prevalence of Spermophilus alaschanicue plague.When the rainfall in the region (not continuously) reaches a certain amount,it will provide favorable conditions for the spread of Yersinia pestis.
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Objective To investigate the relationship between fleas density of Spermophilus alaschanicue and host density as well as meteorological factors.Methods The densities of fleas of Spermophilus alaschanicue and meteorological temperature,precipitation,relative humidity data in the same period from 1977 to 2014 in plague natural foci of Spermophilus alaschanicue of Gansu Province were collected.In order to further establish the multiple linear regression and the stepwise regression analysis model,SAS 9.3 software was used to explore the linear correlation analysis between fleas index number,density of Spermophilus alaschanicue and meteorological factors.Results The average body flea index positively correlated with the density of Spermophilus alaschanicue (r =0.34,P ＜ 0.05),in addition,hole fleas index was in negative correlation with the average temperature of the current and preceding first,second and third years (r =-0.44,-0.39,-0.45,-0.54,P ＜ 0.01).However,hole fleas index positively correlated with the average rainfall of preceding first year (r =0.38,P ＜ 0.05).More specifically,the monthly body flea index was negatively correlated with the average rainfall and the average temperature of current,preceding first,second,and third months,and the average relative humidity of current month (r =-0.23,-0.34,-0.43,-0.29,-0.25,-0.33,-0.36,-0.38,-0.26,P ＜ 0.01).After multiple linear regression analysis,the following equations were obtained:body fleas index =3.983 1 + 0.695 1 × Sperrnophilus density-0.004 9 × average annual rainfall;hole fleas index =10.780 4 + 0.009 1 × average annual rainfall-0.216 2 × annual average relative humidity.Conclusions The relationship between fleas density of Spermophilus alaschanicue and the environment is complex,they have mutual connection as well as mutual restriction.Except Spermophilus density affects the number of fleas,the two most important meteorological factors which affect the flea body index are temperature and rainfall.In addition,the relationship between meteorological factors and flea body index shows somewhat lagging behind for two to three months.
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Objective To apply the DNA barcoding technology for identification of rodent animals and to establish a rodent animal DNA barcode database in Gansu Province.Methods A total of 54 rodent animals were detected.DNA barcoding technology was used to analyze the DNA mitochondrial cytochrome C oxidase subunit Ⅰ (CO Ⅰ) gene sequence in Gansu Province.Results The intra-specific genetic distance was 0-2％ while the interspecific distance ranged from 18％ to 30％.Eight major clusters were apparently showed on a Neighbor joining tree.Conclusion DNA barcoding technology could overcome the shortcomings of the morphological identification,so it could be used to identify the rodent animals and has important implications for disease control and prevention in the natural focus of Gansu Province.
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We studied Yersinia infection and carriage in shepherd dog on the natural foci of Marmota himalayana plague and investigated the substitution or antagonism relationship among three pathogenic Yersinia in nature,providing a novel approach for prevention and control of plague.Blood sample and rectal swab specimens from shepherd dogs were collected.Rectal swab specimens were detected and isolated for Y.enterocolitican and Y.pseudotuberculosis.IHA was used to measure the positive rate of F1 antibody.Results showed that among 88,94,70 and 64 serum specimens respectively from Akesai,Subei,Sunan,and Tianzhu,IHA positive rates were 31.82％,32.98％,2.86％ and 1.56％ separately.A total of 236 anal swab specimens of shepherd dog were collected,among which one Y.kristensenii strain and 2 non-pathogenic Y.enterocolitica strain were recovered from Akesai and Subei respectively,where plague was violently prevalent in animals.All the results indicate that shepherd dogs in natural foci of M.himalayana plague where plague in animals are prevalent with non-pathogenic Y.enterocolitica,is an evidence of antagonism relationship in three pathogenic Yersinia.