| Anthrax is an acute zoonosis caused by the spore-forming bacterium Bacillus anthracis.Humans contact with infected animals or peel off,feed on infected animals leads to cutaneous or intestinal anthrax,which can then be converted to pulmonary anthrax,leading to serious public health problems.Inner Mongolia is an area with high incidence of anthrax,especially in the eastern regions where animal husbandry is more developed and Anthrax is a common,which has become an important public health problem for the local population.In order to further understand the epidemiological profiles of anthrax and the genetic evolution characteristics of Bacillus anthracis in Inner Mongolia.Based on the case data of anthrax reported of Inner Mongolia from 1956 to 2018,epidemiological characteristics of human anthrax in Inner Mongolia was conducted,including in human anthrax distribution,gender,age characteristics of patients and the change regular of epidemic situation.In addition,the strains isolated from patients were genotyped and comparative genomics analyzed to reveale the genetic polymorphism,epidemiological related and origin and evolution.It not only provides a scientific basis for a comprehensive understanding of the epidemiological characteristics of anthrax in Inner Mongolia,but also provides scientific guidance for the formulation strategies of prevention,control and detection of anthrax to against disease.1.The epidemiological investigation of anthrax in Inner Mongolia showed that human anthrax in Inner Mongolia has experienced three epidemic stages and eight epidemic peaks,and the short-term concentrated outbreak is the main characteristics of anthrax epidemic in our region.During the three epidemic periods of anthrax,the proportion of farmers and herdsmen gradually increased,while the proportion of other occupations showed a gradual decrease.The characteristic of occupational distribution showed that from multiple occupations in the early stage to the current occupations dominated by farmers and herdsmen.The age range of onset showed a trend of gradually narrowing from wide to narrow,and the multiple age group tended to stabilize in the 30?60 age group.In addition,the number of outbreaks has gradually decreased,and the number of cases involved in the outbreak has also decreased significantly.The epidemiological trend of anthrax in Inner Mongolia has obviously changes,the incidence rate has continued to stabilize at a low level,with farmers and herdsmen predominant,and the epidemic time is relatively concentrated.This study has important epidemiological significance for a comprehensive understanding of anthrax prevention and control in this region,to provides an available clue for formulating targeted anthrax strategies of monitoring and prevention.2.Bacteriological and serological tests and analysis of case characteristics on clinical samples are of great clinical significance in identifying the source of infection and the diagnosis of the patient's condition.A total of 248 various types of samples of suspected patients were collected from 2010 to 2018,and 27 strains of Bacillus anthracis were isolated,with a positive rate of 10.89%.Microscopic examination of the focus directly by pressing film staining and smear staining after collection can be used for the preliminary microscopic examination of anthrax samples.The mature colonies showed curly hair(lion head)pattern with the observation of low-power microscope,which is a typical biological characteristic of Bacillus anthracis,can make a preliminary judgment on the suspected strain,but it needs to be confirmed by phage lysis test and penicillin bacteriostatic test.In addition,qPCR was good sensitivity and detection timeliness.The results show that,timely and accurate laboratory tests and case characteristic analysis can provide scientific reference for the determination of anthrax epidemic situation.3.The SNP genotype of Bacillus anthracis that isolated from the epidemic scene in Inner Mongolia is of great significance to reveal the genetic and evolutionary characteristics of the strains.In this study,eight SNP loci out of 13,A.Br.006,A.Br.007,A.Br.009,B.Br.001,B.Br.002,B.Br.003,B.Br.004 and A/B.Br.001,of Bacillus anthracis isolated in Inner Mongolia showed that no genetic diversity,while the other five SNP loci,A.Br.001,A.Br002,A.Br.003,A.Br.004 and A.Br.008,showed SNP polymorphism among different strains.Based on SNP cluster analysis of Bacillus anthracis,36 tested strains could be clustered into four groups,including in A.Br.Ames,A.Br.001/002,A.Br.Aust94 and A.Br.008/009 subgroups,of which 18 strains were A.Br.Ames subgroup and 16 strains belonged to A.Br.001/002 subgroup.Moreover,Remainder two strains belongs to A.Br.Aust94 subgroup and A.Br.008/009 subgroup.In this study,the SNP polymorphism and the dominant SNP genotype of anthrax in our region were preliminarily elucidated.4.MLVA-15 genotyping is often used to investigate the outbreak and trace-back of anthrax.In present study,MLVA-15 approach used to analyze 36 strains of Bacillus anthracis isolated in Inner Mongolia,thereby revealing the epidemiological related among the strains.Among the 15 VNTR loci of Bacillus anthracis in Inner Mongolia,the same amplification results were observed in three loci vrrBl,CG3 and VR12,while 1 to 2 strains at the other loci vrrA,vrrB2,vrrC2,VR16,VR17,VR19,VR32 and VR35 were different,and the higher variabilities was detected in three loci pXO1-aat,pXO2-at,vrrC2 and VR23.Based on MLVA-15,36 strains in this study were clustered into 12 MLVA genotypes,of which five were shared genotypes,suggesting that there may be epidemiological correlation among strains;seven were unique genotypes and each genotype represent only one strain.Except for pXO1-aat and pXO2-at loci with higher variability,all strains could be divided into five genotypes,and the addition of these two loci increased the number of genotypes from 5 to 12,which is helpful for the differentiate of strains in Inner Mongolia from other regions,and provides a basis for the trace-back investigation of anthrax.5.The whole genome sequencing and comparative genome analysis of Bacillus anthracis is the best approach to understand the correlation and evolutionary characteristics of Bacillus anthracis.In this study,the whole genome of seven strains of Bacillus anthracis isolated from Inner Mongolia was sequenced.The results show that,the core genome of Bacillus anthracis in Inner Mongolia is relatively stable,but the genome is open,and new genes can be obtained by a variety of means.It is predicted that BA130 and BA132 have a potential for obtained more new genes.Based on the phylogenetic analysis of core genes,seven strains of Bacillus anthracis were divided into two groups(A,B).The strains in groups A and B were from Chifeng and Hinggan League,respectively,suggesting that the core genomes of Bacillus anthracis in Inner Mongolia showed obvious regional aggregation.Group B included five strains,of which four strains were isolated from patients(BA125,BA130,BA132 and BA 168)and one strain is isolated from sick cattle(BA77).BA77,BA125 and BA130 showed the same A.Br.001/002 genotype,suggesting an epidemiological relationship between strains.Moreover,strains from this study had high genetic simmillay with strains from Korea south,and Japan,this data providing available information for understanding genetic and evolution characteristics of strains from these nations. |
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