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Objective:To investigate the changes in adaptive phenotypes of Yersinia pestis ( Yp) during successive passages in macrophages. Methods:A Yp strain of 201-MI was induced by 50 successive passages of Yp 201 strain in Raw264.7 cells. Phenotypic characteristics of 201 and 201-MI strains were compared by analyzing their survival rates in macrophages, growth curves, biofilm formation abilities, acid and hydrogen peroxide-stress tolerance, and virulence to mammal cells (Raw264.7 and HeLa cells) and mice. Results:Comparing with 201 strain, 201-MI strain showed various phenotypic changes, including higher survival rate in Raw264.7 cells, faster growth in iron-deficient medium, higher tolerance to acid and hydrogen peroxide, decreased biofilm formation ability, and less damages to Raw264.7 and HeLa cells. More-over, 201-MI strain showed decreased virulence to mice in both subcutaneous and intraperitoneal challenges. Preliminary comparative genomics analysis revealed some indel and nonsense mutations in 201-MI strain, which might account for its phenotype changes.Conclusions:After successive passages in macrophages, Yp showed some phenotypic changes, which might reflect its adaptive evolution under the pressure of macrophages. Detailed multi-omics analysis would be of great help to understand the underlying genetic mechanisms of these changes, and the related Yp-macrophage interaction processes as well.
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Objective:To observe the efficacy of levofloxacin and moxifloxacin in the treatment of experimental plague in guinea pigs.Methods:A total of 70 SPF guinea pigs, female, weighing 250 to 300 g, were selected and randomly divided into 7 groups according to body weight by random number table. There were 10 guinea pigs in each group: levofloxacin 24, 48, 72 h groups, moxifloxacin 24, 48, 72 h groups (drug treatment was carried out after being infected with Yersinia pestis for 24, 48 and 72 h, respectively) and control group (without treatment). Experimentally infected plague model was established through guinea pigs subcutaneous injection of 141 strains of Yersinia pestis [1 × 10 7 colony forming unit (CFU)]; referring to the adult dose in the "National Pharmacopoeia of the People's Republic of China", the daily dose of guinea pigs was converted by Shi Xinyou's animal conversion coefficient method for treatment, the doses of levofloxacin and moxifloxacin in each guinea pig were 12.0 and 9.6 mg/d, respectively for 9 days. The guinea pigs were killed 9 days after drug withdrawal for bacteriological examination and pathological observation, and the cure rate was calculated. Results:The cure rates of levofloxacin 24, 48 and 72 h groups were 100.0% (10/10), 70.0% (7/10) and 6/6, respectively. The cure rates of moxifloxacin 24, 48 and 72 h groups were 100.0% (10/10), 100.0% (10/10) and 5/7, respectively, and the cure rate of animals in the control group was 0 (0/10). Compared with the control group, there were significant differences in the efficacy of moxifloxacin 24, 48 and 72 h groups and levofloxacin 24, 48 and 72 h groups ( P < 0.05). There was no significant difference between the two drugs at the same starting time ( P > 0.05). Conclusion:The effects of levofloxacin and moxifloxacin on animal plague infection are ideal and the two drugs can be used as a substitute for streptomycin in plague treatment under special circumstances.
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Objective:To explore the biochemical characteristics, virulence factors and other phenotypes of the strains of Yersinia pestis isolated in Jianchuan County Yunnan Province in 2017, and to analyze the nature and source of the new plague epidemic. Methods:Three strains of Yersinia pestis (JC109 rat, JC109 fleas and JC113) isolated from Daqing Village, Jinhua Town, Jianchuan County, Dali Prefecture, Yunnan Province in 2017, and 2 associated strains of Yersinia pestis (LJ01 in Yulong County, Lijiang City and LJ04 in Gucheng District of Lijiang City), 5 control strains ( Yersinia pestis JC1332, LJ485, BN2636, EV-76 and Yersinia pseudotuberculosis PST-1), preserved by the Central Laboratory of Yunnan Institute for Endemic Disease Control and Prevention were collected. The biochemical characteristics and ecotypes of Yersinia pestis were analyzed by using arabinose, rhamnose, denbiose, maltose and glycerol fermentation experiments and nitrate reduction experiments. Combining pigmentation factor (pgm), virulence antigen (VW) detection and nutritional requirements test results to determine the virulence of Yersinia pestis. Results:The Yersinia pestis JC109 rat, JC109 fleas and JC113 all fermented arabinose, maltose and glycerol, but didn't ferment rhamnose and denbiose; and the nitrate reduction test was positive. The ecological type belonged to the Himalayan Marmot plague strain of Qinghai-Tibet plateau. The virulence factors pgm and VW tests were positive, the nutritional requirement type was phenylalanine dependent and glutamate independent. It had the same phenotype as the LJ01 strain, but different from the JC1332 strain. Conclusions:The newly isolated strains in Jianchuan County are the same as those in the Lijiang Yulong wild rodent plague foci. This outbreak may have been imported from the Lijiang Yulong wild rodent plague foci to the south.
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Objective:To analyze the pathogenic characteristics of Yersinia pestis in a plague natural foci in Qinghai-Tibet Plateau. Methods:In this study, 1 378 strains of Yersinia pestis isolated from different regions, hosts and vectors in Qinghai-Tibet Plateau from 1954 to 2016 were taken as the research objects. Phenotypic characteristics, plasmid spectrum and genotype of the strains were studied by using conventional techniques and molecular biological techniques. The etiology and geographical distribution of the plague were studied. Results:There were 6 biochemical types of Yersinia pestis in Qinghai-Tibet Plateau, namely Qinghai-Tibet Plateau, Qilian Mountain, Gangdis Mountain, Kunlun Mountain A, Kunlun Mountain B and Chuanqing Plateau. This study found that the Qinghai-Tibet Plateau type strain was not only distributed in north Tibet Plateau, but also distributed in south Tibet, and the distribution of Gangdis Mountain type strain extended to south Tibet. Four virulence factors (capsule antigen, yersinin, virulence antigen and pigmentation factor) were found in 79.97% (1 102/1 378) Yersinia pestis. The results also showed that there were 12 kinds of plasmids carried by Yersinia pestis strains in Qinghai-Tibet Plateau, which constituted 17 kinds of plasmid spectrum. There were 3 kinds of the largest plasmids with taxonomic properties, forming their respective relatively independent distribution areas. The study of different regions (DFR) type showed that 5, 8, 14, 19, 32 and 44 of 1 378 strains were the main genotypes, and the main genome types had obvious geographical distribution. Conclusions:All the tested strains have the characteristics of plague pathogen in Qinghai-Tibet Plateau. The polymorphism of the main hosts, vectors and the ecological landscape of plague geography in the plague foci in Qinghai-Tibet Plateau may lead to the diversity of biochemical characters, plasmid spectrum and geno types of Yersinia pestis.
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Objective@#To investigate reciprocal regulation between Fur and two RyhB homologs in @*Methods@#Regulatory relationships were assessed by a combination of colony morphology assay, primer extension, electrophoretic mobility shift assay and DNase I footprinting.@*Results@#Fur bound to the promoter-proximal DNA regions of @*Conclusion@#Fur and the two RyhB homologs exert negative reciprocal regulation, and RyhB homologs have a positive regulatory effect on biofilm formation in
Subject(s)
Bacterial Proteins/metabolism , Biofilms , Gene Expression Regulation, Bacterial/physiology , Yersinia pestis/physiologyABSTRACT
Objetivo: caracterizar aspectos epidemiológicos e clínicos fundamentais, discutir a metodologia do diagnóstico e tecer recomendações sobre as condutas perante a suspeição de casos de peste. Métodos: revisão bibliográfica e levantamento das internações e mortes por peste registradas no Sistema de Informações Hospitalares do Sistema Único de Saúde. Resultados e conclusões: a existência de diagnósticos equivocados de uma doença potencialmente fatal, além dos registros hipotéticos de internações e mortes, constitui um desafio a ser superado, pois espelha uma situação inaceitável, em que um possível e insólito diagnóstico não é investigado e acumula-se nos sistemas de informação.
Objective: to characterize ground epidemiological and clinical aspects of, discuss the methodology of diagnosis and draw recommendations about the management of suspect cases of plague. Methods: literature review and data collection of hospitalizations and deaths due to plague recorded in the Hospital Information System of the Unified Health System. Results and conclusions: the existence of mistaken diagnoses of a potentially fatal disease, as well as hypothetical records of hospitalization and deaths, is a challenge to be overcome, because it reflects an unacceptable panorama in which a possible and unusual diagnosis is not investigated and accumulates in the information systems.
Subject(s)
Yersinia pestis , EpidemiologyABSTRACT
RESUMEN La peste es una enfermedad reemergente causada por Yersinia pestis. Los humanos generalmente adquieren la enfermedad por picaduras de pulgas. La peste es una enfermedad sistémica fulminante, siendo la peste neumónica la forma más letal. El diagnóstico tardío es una de las principales causas de mortalidad y diseminación de la enfermedad, dado que limita la efectividad de las medidas de control. Presentamos el caso de un varón de 42 años, que previamente había viajado a una zona endémica de peste, y luego presentó hiperpirexia, hipotensión, y adenopatía inguinal inflamatoria. A pesar del cuadro clínico muy característico, nadie (antes del ingreso a nuestro hospital) sospechó peste. Se inició una combinación antibiótica efectiva y tratamiento intensivo recién al quinto día de enfermedad. El paciente evolucionó con shock séptico, falla respiratoria, y muerte. Se confirmó peste por reacción en cadena de polimerasa (PCR). Este caso enfatiza la importancia de tener un alto índice de sospecha para peste.
ABSTRACT Plague is a re-emerging disease caused by the bacteria Yersinia pestis. Humans usually get the disease through the bite of an infected flea. Plague is a fulminant systemic disease, with pneumonic plague being the most lethal form. Late diagnosis is one of the main causes of mortality and spread of the disease, as it limits the effectiveness of control measures. We present the case of a 42-year-old male, who had previously traveled to an endemic plague area and then presented hyperpyrexia, hypotension, and inflammatory inguinal adenopathy. Despite the very characteristic clinical picture, nobody (before admission to our hospital) suspected plague. An effective combination of antibiotics and intensive treatment was initiated only on the fifth day of illness. The patient went into septic shock, respiratory failure, and death. Plague was confirmed by polymerase chain reaction (PCR). This case emphasizes the importance of having a high suspicion rate for plague.
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Objective@#To analyze the epidemic trend of the domestic rodents plague natural foci among animals in Yunnan Province, so as to provide a basis for formulating plague prevention and control strategies.@*Methods@#Monitoring and summarizing data of plague epidemic situation in Yunnan Province from 1950 to 2018 were collected from Yunnan Institute for Endemic Disease Control and Prevention. Descriptive epidemiological method was used to analyze the prevalence of plague among animals. Simple linear regression equations were established using SPSS 21.0 software to analyze the correlation between plague epidemics and rat density, dyeing rate and human plague in 1982-2007.@*Results@#From 1950 to 2018, 51 counties (cities) in 12 regions (prefectures) were confirmed to have animal epidemics in Yunnan Province, and 1 722 epidemic spots were found. A total of 7 152 monitoring sites had been set up in 98 counties (cities). From 1950 to 1956, the plague epidemic in Yunnan Province was confined to western Yunnan; the 1957-1981 was the resting period; 1982-2007, the epidemic spread from west and southwest to south, central, southeast and east of Yunnan Province; after 2008 entered resting period again. The epidemic season of plague was mainly from June to November. Simple linear regression equation analysis showed that the regression equation Y = 9.112 + 44.848X between animal plague (Y) and rat density (X) and the regression equation Y = 2.261 + 0.139X between human plague (Y) and animal plague (X) were statistically significant (F = 9.306, 5.371, P < 0.05).@*Conclusions@#The epidemic trend of plague among animals in Yunnan Province is a "wave type". There is a correlation between animal plague and rat density and human plague. It is the key to prevent the occurrence of animal plague and human plague by monitoring the plague epidemics in animals.
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Objective@#To investigate the correlation of meteorological factors with the numbers of marmots and parasitic fleas in the plague foci of Himalayan marmot in Subei County and Sunan County of Gansu Province.@*Methods@#The surveillance data(from Gansu Provincial Center for Disease Control and Prevention) of natural plague foci of Subei, Sunan of Himalayan marmot from 1982 to 2016 and the meteorological factors data (from China Meteorological Data Sharing Service Network) such as annual average temperature, rainfall and relative humidity during the same period were collected. The correlation between marmot density, body flea index and meteorological factors were analyzed by SAS 9.3 software. Based on the meteorological data as an independent variable in current year and previous 1, 2, and 3 years (relative to previous 1, 2, and 3 years as the reference), the marmot density as the dependent variable, the time series semiparametric generalized additive model (GAM) was established to quantitatively study the nonlinear effect of meteorological factors on the marmot density by R2.3.2 software.@*Results@#From 1982 to 2016, the marmot density in Subei County of Gansu Province was 0.29-6.63 per hectare, and the body flea index range was 0.04-4.56; the marmot density in Sunan County of Gansu Province was 1.22-7.92 per hectare, and the body flea index range was 0.06-0.42. In Subei County, the marmot density was correlated with the previous 1 year rainfall and relative humidity, respectively (r= 0.43, 0.36, P < 0.05), and negatively correlated with the average temperature of the year and the previous 1, 3 years (r=-0.58,-0.55,-0.41, P < 0.05). In Sunan County, the marmot density was correlated with the relative humidity of the year and the previous 1 year rainfall and relative humidity, respectively (r= 0.36, 0.57, 0.43, P < 0.05). In Subei County, the body flea index was negatively correlated with the average temperature of the year and the previous 1, 2, 3 years, respectively(r=-0.57,-0.43,-0.31,-0.37, P < 0.05). In Sunan County, there was a negative correlation between the body flea index and the average temperature of the year and the previous 1, 2, 3 years (r=-0.71,-0.46,-0.38,-0.40, P < 0.05). After controlling other influencing factors, the results of the GAM showed that for every 1 mm increase in rainfall of the year in Subei County, the marmot density increased 0.93%; for every 1% increase in relative humidity of the previous 3 year in Subei County, the marmot density increased 25.34%; for every 1 mm increase in rainfall of the previous 3 year in Sunan County, the marmot density increased 1.69%.@*Conclusions@#The numbers of marmots in the plague foci of Himalayan marmot in Subei County and Sunan County of Gansu Province are closely related to rainfall and relative humidity, and the influence has different hysteresis effects. Surface temperature is a important factor affecting the population of parasitic fleas.
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Objective@#To investigate whether plague phages were present in the indicator animals of plague foci in Yunnan Province, and to explore their epidemiological significance.@*Methods@#Anus swabs were collected from indicator animals (dogs or cats) of the 41 plague affected villages in 26 towns of 10 cities (counties, districts) of Yunnan plague foci from November of 2015 to March of 2018. The Yersinia pestis phages were isolated by plague vaccine strain EV76. The isolation of plague phages from different plague foci, the isolation of plague phages from different canine species (cats), the polymorphism of plaque and the host spectrum of phages were analyzed.@*Results@#A total of 1 014 indicator animals (1 003 dogs and 11 cats) were studied, and 102 of plague phages were isolated. In the 10 cities (counties, districts), plague phages were only not isolated from Lancang County, and the plague phages were isolated from the other 9 cities (counties, districts). The separation rates from high to low were as follows: Yiliang County (21.00%, 21/100), Menghai County (19.23%, 25/130), Yuanjiang County (11.63%, 10/86), Midu County (11.50%, 13/113), Wenshan County (10.10%, 10/99), Mile Country (7.07%, 7/99), Lianghe County (6.67%, 7/105), Baoshan Longyang District (4.90%, 5/102) and Gengma County (3.81%, 4/105). Of the 102 plague phages, 75 were isolated from the native dogs (Chinese pastoral dogs, 9.32%, 75/805), 20 from the pug dogs (13.70%, 20/146), 5 from the wolf dogs (17.24%, 5/29), 1 from Samoye (1/4) and 1 from Alaska dog (1/2). The plaque of the phage was divided by five appearance of complete lysis (the plate was clear), large (2.5-4.0 mm), big (1.5-< 2.5 mm), middle (0.5-< 1.5 mm) and small (< 0.5 mm). The representative phages were all of the Myoviridae family. Most of the phages could lysis the strains of Yersinia pestis, and some phages could lysis Shigella and type 5 Yersinia pseudotuberculosis (PST5).@*Conclusion@#The plague phages are present in the plague foci of Yunnan, and the phages are polymorphic.
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Objective To analyze the epidemic trend of the domestic rodents plague natural foci among animals in Yunnan Province,so as to provide a basis for formulating plague prevention and control strategies.Methods Monitoring and summarizing data of plague epidemic situation in Yunnan Province from 1950 to 2018 were collected from Yunnan Institute for Endemic Disease Control and Prevention.Descriptive epidemiological method was used to analyze the prevalence of plague among animals.Simple linear regression equations were established using SPSS 21.0 software to analyze the correlation between plague epidemics and rat density,dyeing rate and human plague in 1982-2007.Results From 1950 to 2018,51 counties (cities) in 12 regions (prefectures) were confirmed to have animal epidemics in Yunnan Province,and 1 722 epidemic spots were found.A total of 7 152 monitoring sites had been set up in 98 counties (cities).From 1950 to 1956,the plague epidemic in Yunnan Province was confined to western Yunnan;the 1957-1981 was the resting period;1982-2007,the epidemic spread from west and southwest to south,central,southeast and east of Yunnan Province;after 2008 entered resting period again.The epidemic season of plague was mainly from June to November.Simple linear regression equation analysis showed that the regression equation Y =9.112 + 44.848X between animal plague (Y)and rat density (X) and the regression equation Y =2.261 + 0.139X between human plague (Y) and animal plague (X) were statistically significant (F =9.306,5.371,P ＜ 0.05).Conclusions The epidemic trend of plague among animals in Yunnan Province is a "wave type".There is a correlation between animal plague and rat density and human plague.It is the key to prevent the occurrence of animal plague and human plague by monitoring the plague epidemics in animals.
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Objective To investigate the correlation of meteorological factors with the numbers of marmots and parasitic fleas in the plague foci of Himalayan marmot in Subei County and Sunan County of Gansu Province.Methods The surveillance data (from Gansu Provincial Center for Disease Control and Prevention) of natural plague foci of Subei,Sunan of Himalayan marmot from 1982 to 2016 and the meteorological factors data (from China Meteorological Data Sharing Service Network) such as annual average temperature,rainfall and relative humidity during the same period were collected.The correlation between marmot density,body flea index and meteorological factors were analyzed by SAS 9.3 software.Based on the meteorological data as an independent variable in current year and previous 1,2,and 3 years (relative to previous 1,2,and 3 years as the reference),the marmot density as the dependent variable,the time series semiparametric generalized additive model (GAM) was established to quantitatively study the nonlinear effect of meteorological factors on the marmot density by R2.3.2 software.Results From 1982 to 2016,the marmot density in Subei County of Gansu Province was 0.29-6.63 per hectare,and the body flea index range was 0.04-4.56;the marmot density in Sunan County of Gansu Province was 1.22-7.92 per hectare,and the body flea index range was 0.06-0.42.In Subei County,the marmot density was correlated with the previous 1 year rainfall and relative humidity,respectively (r =0.43,0.36,P＜ 0.05),and negatively correlated with the average temperature of the year and the previous 1,3 years (r =-0.58,-0.55,-0.41,P ＜ 0.05).In Sunan County,the marmot density was correlated with the relative humidity of the year and the previous 1 year rainfall and relative humidity,respectively (r =0.36,0.57,0.43,P ＜ 0.05).In Subei County,the body flea index was negatively correlated with the average temperature of the year and the previous 1,2,3 years,respectively (r =-0.57,-0.43,-0.31,-0.37,P ＜ 0.05).In Sunan County,there was a negative correlation between the body flea index and the average temperature of the year and the previous 1,2,3 years (r =-0.71,-0.46,-0.38,-0.40,P ＜ 0.05).After controlling other influencing factors,the results of the GAM showed that for every 1 mm increase in rainfall of the year in Subei County,the marmot density increased 0.93％;for every 1％ increase in relative humidity of the previous 3 year in Subei County,the marmot density increased 25.34％;for every 1 mm increase in rainfall of the previous 3 year in Sunan County,the marmot density increased 1.69％.Conclusions The numbers of marmots in the plague foci of Himalayan marmot in Subei County and Sunan County of Gansu Province are closely related to rainfall and relative humidity,and the influence has different hysteresis effects.Surface temperature is a important factor affecting the population of parasitic fleas.
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Objective To investigate whether plague phages were present in the indicator animals of plague foci in Yunnan Province,and to explore their epidemiological significance.Methods Anus swabs were collected from indicator animals (dogs or cats) of the 41 plague affected villages in 26 towns of 10 cities (counties,districts) of Yunnan plague foci from November of 2015 to March of 2018.The Yersinia pestis phages were isolated by plague vaccine strain EV76.The isolation of plague phages from different plague foci,the isolation of plague phages from different canine species (cats),the polymorphism of plaque and the host spectrum of phages were analyzed.Results A total of 1 014 indicator animals (1 003 dogs and 11 cats) were studied,and 102 of plague phages were isolated.In the 10 cities (counties,districts),plague phages were only not isolated from Lancang County,and the plague phages were isolated from the other 9 cities (counties,districts).The separation rates from high to low were as follows:Yiliang County (21.00％,21/100),Menghai County (19.23％,25/130),Yuanjiang County (11.63％,10/86),Midu County (11.50％,13/113),Wenshan County (10.10％,10/99),Mile Country (7.07％,7/99),Lianghe County (6.67％,7/105),Baoshan Longyang District (4.90％,5/102) and Gengma County (3.81％,4/105).Of the 102 plague phages,75 were isolated from the native dogs (Chinese pastoral dogs,9.32％,75/805),20 from the pug dogs (13.70％,20/146),5 from the wolf dogs (17.24％,5/29),1 from Samoye (1/4) and 1 from Alaska dog (1/2).The plaque of the phage was divided by five appearance of complete lysis (the plate was clear),large (2.5-4.0 mm),big (1.5-＜ 2.5 mm),middle (0.5-＜ 1.5 mm) and small (＜ 0.5 mm).The representative phages were all of the Myoviridae family.Most of the phages could lysis the strains of Yersinia pestis,and some phages could lysis Shigella and type 5 Yersinia pseudotuberculosis (PST5).Conclusion The plague phages are present in the plague foci of Yunnan,and the phages are polymorphic.
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Objective To analyze the biological characteristics of Yersinia pestis strains in Haixi Prefecture,Qinghai Province,in order to provide a scientific basis for plague prevention and control in future.Methods Totally 181 strains were separated from variety kinds of host in Haixi Prefecture,Qinghai Province from 1957 to 2011,and these strains were conducted biochemical test,virulence factor evaluation,plasmid analysis,different region (DFR) genotyping,drug and disinfectant resistant genes detection;79 of the 181 strains were examined by toxicity test and classified according to the criteria (minimum lethal dose:MLD≤ 10 000 was velogenic strain,10 000 ＜ MLD ＜ 100 000 was moderate virulence strain,MLD ≥ 100 000 was hypovirulent strain).Results According to six biochemical typing about gelatin candy,rhamnose,maltose,melibiose,glycerin and denitrification,the 181 strains of Yersinia pestis were antique biovar and Qing-Tibet Plateau ecotype.Aproportion of 81.22％ (147/181) of Yersiniapestis strains contained all the four virulence factors (F1,Pst Ⅰ,VW,Pgm).Totally 63.54％ (115/181) of the strains contained 3 kinds of plasmid-6 × 106,45 × 106,and 52 × 106;31.49％ (57/181) of the strains contained 3 kinds of plasmid-6 × 106,45 × 106,and 65 × 106.The strains had 8 genomovars,and were given priority to genomovar 8 (109 strains),secondly,genomovar 32 (33 strains),genomovar 5 (20 strains),genomovar 1b(i4 strains),genomovar 44 (2 strains),genomovar 7 (1 strain),genomovar 37 (1 strain),and genomovar 49 (1 strain).Among the 181 Yersinia pestis strains,strains with genes related to streptomycin resistance,sulfanilamide resistance,beta lactam resistance and disinfectant resistance were not found;and 75 of 79 strains were velogenic strains by toxicity test (MLD ≤ 10 000),accounted for 94.94％ (75/79).Conclusion The strains separated in Haixi Prefecture,Qinghai Province have the characteristics of Qinghai-Tibet Plateau plague's pathogen and have strong toxicity;all strains don't have the characteristics of drug and disinfectant resistance genes.
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Objective To analyze the relationship between meteorological variables and the prevalence of marmot plague in the Himalayan marmot foci of Subei County,Gansu Province.Methods The surveillance data (from Gansu Provincial Center for Disease Control and Prevention) on human plague,the meteorological factors (average rainfall,temperature,relative humidity) data (from China Meteorological Data Sharing Service Network) of the current and preceding (relative to current year as a reference) first,second and third years and meteorological factors data of the current and preceding first,second and third months in Subei of Himalayan marmot foci from 1973 to 2014 were collected.The association of positive rate of plague bacteriological detection and meteorological factors was evaluated by using SAS 9.3 software.The influence of meteorological factors on the epidemic of marmot plague was analyzed by the logistic regression analysis.Results From 1973 to 2014,6 human plague cases with 5 dead cases occurred in Subei County.The positive rate of plague bacteriological detection was positively correlated with the average relative humidity of current year and the average temperature of preceding first year (r =0.366,0.385,P ＜ 0.05),and it was negatively correlated with the average relative humidity of preceding third year (r =-0.304,P ＜ 0.05);the positive rate of plague bacteriological detection was positively correlated with the average rainfall of preceding first month (r =0.212,P ＜ 0.05),and it was negatively correlated with the average relative humidity of preceding second and third months (r =-0.196,-0.201,P ＜ 0.05).The risk factor of animal plague epidemic in marmot foci in Subei County was average temperature of current month [odds ratio (OR) =1.304,95％ confidence intervals (CI):1.195-1.422],and the protective factor was average relative humidity of preceding third month (OR =0.960,95％CI:0.932-0.988).Conclusions The prevalence of marmot plague is closely associated with meteorological factors in the natural plague foci of Subei County of Gansu Province.The temperature not only plays a role in promoting the prevalence of plague,but also has a lagging effect.Therefore,the meteorological factors can be considered as a reference of the plague prevalence in Himalayan marmot plague foci.
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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 compare the coding sequences (CDS) of Yersinia pestis D106004 strain from Yulong County in Yunnan Province and Z176003 strain from Qing-Tibet Plateau in order to find the differences between their genomes and the genetic characteristics. Methods The CDS of Yersinia pestis D106004 strain and Z176003 strain were searched and compared by BLAST. Twenty-two differential CDS were selected to design 22 pairs of primers. PCR amplification was carried out in 119 representative plague strains from different isolation sources (natural foci of Himalayan marmot plague in the Qinghai-Tibet Plateau, natural foci of Apodemus chevrieri and Eothenomys miletus plague in Yunnan), time span of about 50 years, and distribution in six ecological types including Tibet, Qinghai, Sichuan, Gansu and Yunnan, and PCR products were sequenced and verified. The strains were all from the State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Infectious Disease Control and Prevention, Chinese Center for Disease Control and Prevention. Results In 119 representative plague strains of 6 ecological types, the cumulative sequence length of 22 differential CDS PCR amplification products was 2.13 × 106 bp. Among the 119 representative plague strains in the foci of Yulong D106004 strain and Qinghai-Tibet Plateau Z176003 strain, 22 differential CDS had high homology, there was no difference in 78.2％ (2047/2618) sequences of differential CDS, and 21.8％ (571/2618) sequences had three types of gene mutations ( deletion , missense and frameshift mutations). The characteristics of the differences were stable in the 6 ecological plague strains of the foci, and they were divided into 6 geographical distributions. Conclusion Yulong D106004 strain and Qinghai-Tibet Plateau Z176003 strain have high homology, close genetic relationship, and little difference in genome, but the genetic characteristics of different ecotype strains are stable.
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ABSTRACT We developed a loop-mediated isothermal amplification (LAMP) assay for the detection of Y. pestis by targeting the 3a sequence on chromosome. All 11 species of the genus Yersinia were used to evaluate the specificity of LAMP and PCR, demonstrating that the primers had a high level of specificity. The sensitivity of LAMP or PCR was 2.3 or 23 CFU for pure culture, whereas 2.3 × 104 or 2.3 × 106 CFU for simulated spleen and lung samples. For simulated liver samples, the sensitivity of LAMP was 2.3 × 106 CFU, but PCR was negative at the level of 2.3 × 107 CFU. After simulated spleen and lung samples were treated with magnetic beads, the sensitivity of LAMP or PCR was 2.3 × 103 or 2.3 × 106 CFU, whereas 2.3 × 105 or 2.3 × 107 CFU for magnetic bead-treated liver samples. These results indicated that some components in the tissues could inhibit LAMP and PCR, and liver tissue samples had a stronger inhibition to LAMP and PCR than spleen and lung tissue samples. LAMP has a higher sensitivity than PCR, and magnetic bead capture of DNAs could remarkably increase the sensitivity of LAMP. LAMP is a simple, rapid and sensitive assay suitable for application in the field or poverty areas.
Subject(s)
Humans , Plague/microbiology , DNA, Bacterial/genetics , Nucleic Acid Amplification Techniques/methods , Magnetics/methods , Yersinia pestis/isolation & purification , Yersinia pestis/classification , Yersinia pestis/genetics , DNA, Bacterial/isolation & purification , DNA, Bacterial/chemistry , Polymerase Chain Reaction , Sensitivity and Specificity , Immunomagnetic Separation , DNA Primers/genetics , Nucleic Acid Amplification Techniques/instrumentation , Magnetics/instrumentationABSTRACT
Frontopsylla spadix is one of important transmission vectors of plague in the wild rat foci in Yunnan Province.In the classification,it belongs to Leptopsyllidae and Frontopsylla,with agile activities and a wide range of hosts.Based on domestic and international literatures,this paper reviews the taxonomic position and identifies features of Frontopsylla spadix,together with its distribution,life cycle,disease transmission,artificial rearing,isozyme and some other aspects.The paper is an attempt to provide more data for the surveillance and control of Frontopsylla spadix and its related flea-borne diseases.
ABSTRACT
Objective To investigate whether the host animals of Yulong plague foci carry Yersiniapestis phage,and to identify isolated plague phage.Methods Rodent specimens were collected in 5 villages of Yulong plague foci in spring and autumn of 2016,respectively.Vaccine strain EV76 was used as breeding bacteria.Phage was isolated from the specimens by double-layer plate method and plaque morphology was identified.Results ① Totally 409 samples collected in spring failed in phage isolation.A total of 40 of Yersinia pestis phages were isolated from 444 samples in autumn,and the total isolation rate was 9.01％ (40/444).② The Yersinia pestis phages were isolated in all of 5 villages,and the isolation rate was of no significant difference (x2 =5.055,P ＞ 0.05).③ Of the 40 strains of phage,37 strains were isolated from Apodemus chevrieri,2 strains from Eothenomys Miletus and 1 strain from Crocidura Dracula.④Based on the appearance,the plaque of the phage was divided into three:large (diameter 1.5-2.5 mm),middle (0.5-＜ 1.5 mm) and small (＜ 0.5 mm).Conclusion There is a higher number of plague phage in the host animals of the plague foci in Yulong County of Yunnan Province,the plaques are diverse in morphology,and their biological characteristics may be polymorphic.