Anthrax is an acute infectious zoonotic disease caused by Bacillus anthracis, a bacterium that is considered a potential biological warfare agent. Bacillus bacteriophages shape the composition and evolution of bacterial communities in nature and therefore have important roles in the ecosystem community. B. anthracis phages are not only used in etiological diagnostics but also have promising prospects in clinical therapeutics or for disinfection in anthrax outbreaks. In this study, two temperate B. anthracis phages, vB_BanS_A16R1 (A16R1) and vB_BanS_A16R4 (A16R4), were isolated and showed siphovirus-like morphological characteristics. Genome sequencing showed that the genomes of phages A16R1 and A16R4 are 36,569 bp and 40,059 bp in length, respectively. A16R1 belongs to the genus Wbetavirus, while A16R4 belongs to the genus Hubeivirus and is the first phage of that genus found to lyse B. anthracis. Because these two phages can comparatively specifically lyse B. anthracis, they could be used as alternative diagnostic tools for identification of B. anthracis infections.

Introduction: The epidemic of human anthrax is at a low level in China in recent years, but the reported incidence increased in 2021. In order to understand the current landscape of research and knowledge about anthrax in China, the epidemiological characteristics of anthrax in humans from 2018 to 2021 were analyzed and the prevention and control suggestions were proposed. Methods: Surveillance data of anthrax in humans and livestock, together with human outbreaks data during 2018-2021, were collected and analyzed by descriptive statistics methods. The number and proportion of outbreaks, cases and deaths by provincial-level administrative divisions (PLADs), clinical types, and contributing factors were calculated. Results: A total of 1,244 cases of human anthrax and 53 outbreaks were reported from 2018 to 2021 in China. While the incidence of anthrax declined from 2018 to 2020, it increased in 2021. The regions of anthrax were mainly located in the west and the northeast PLADs of China, though cases were reported in some central and eastern PLADs in 2021. Young and middle-aged men involved in animal husbandry were found to be at a higher risk of anthrax. All the reported outbreaks were associated with the exposure of infected livestock. A total of 296 livestock anthrax cases were reported. Conclusions: The increased incidence and wider geographical distribution of human anthrax in 2021 were found to be the result of inadequate supervision of diseased animals as well as updated diagnostic criteria. As such, the monitoring of risk factors and emergency preparation procedures should be strengthened at the national level. In addition, it is also critical to strengthen health education for high-risk occupational groups and strengthen professional training for local clinicians. Finally, more measures should be carried out to strengthen anthrax surveillance in livestock husbandry.

On 12 November 2019, one couple from the Sonid Left Qi (County) in the Inner Mongolia Autonomous Region was diagnosed with pneumonic plague in Beijing. The wife acquired the infection from her husband. Thereafter, two bubonic plague cases were identified in Inner Mongolia on November 16th and 24th. In this study, genome-wide single nucleotide polymorphism (SNP) analysis was used to identify the phylogenetic relationship of Yersinia pestis strains isolated in Inner Mongolia. Strains isolated from reservoirs in 2018 and 2019 in Inner Mongolia, together with the strain isolated from Patient C, were further clustered into 2.MED3m, and two novel lineages (2.MED3q, 2.MED3r) in the 2.MED3 population. According to the analysis of PCR-based molecular subtyping methods, such as the MLVA 14 scheme and seven SNP allele sequencing, Patients A/B and D were classified as 2.MED3m. In addition, strains from rodents living near the patients’ residences were clustered into the same lineage as patients. Such observations indicated that human plague cases originated from local reservoirs. Corresponding phylogenetic analysis also indicated that rodent plague strains in different areas in Inner Mongolia belong to different epizootics rather than being caused by spreading from the same epizootic in Meriones unguiculatus in 2019.

Objective To assess the incidences of key infectious diseases in the summer of 2021 in China and provide reference and guidance for further surveillance, prevention and control of these infectious diseases in the summer of 2021. Methods The incidence data of notifiable infectious diseases from January to May 2021 in China collected from National Notifiable Infectious Disease Reporting System and the influenza surveillance system were analyzed and compared with the incidence data of the diseases during the same periods from 2017 to 2020 by experts to evaluate and predict the incidence trends of the key infectious diseases in summer 2021. Results As of May 23, 2021, a total of 2.47 million cases of notifiable diseases had been reported in China, a decrease of 5% compared with the same period in 2020 (2.60 million cases). After the exclusion of COVID-19 cases, the case number was 42% lower than that during the same period in 2019 (4.26 million cases) and 24% lower than the average of the same periods from 2017 to 2019 (3.24 million cases). A total of 7162 deaths had been reported in China, which was 39% lower than that during the same period in 2020 (11671 deaths) and 6% lower than the average of the same periods from 2017 to 2019 (7639 deaths). From January to May 2021, a total of 27 000 brucellosis cases were reported, which was 73% higher than that during the same period in 2020 and 70% higher than the average during the same periods from 2017 to 2019. The incidence of brucellosis in Inner Mongolia has increased rapidly since 2017, and the incidences of brucellosis in Ningxia and Gansu have been in increase since 2018. During this period, a total of 430 000 cases of hand foot and mouth disease (HFMD), including 433 severe cases, were reported, an increase of 985% and 1070% compared with the same period in 2020, a total of 15 dengue fever cases were reported, which was 86% lower than that during the same period in 2020 (110 cases), a total of 59 anthrax cases were reported, which was higher than that during the same period in 2020 (47 cases), a total of 107 000 influenza cases were reported, which was 90% lower than that during the same period in 2020 and a total of 11 cases of human infection with avian influenza virus were reported, which was slightly higher compared with the same period in previous years, all the human infections with avian influenza virus occurred sporadically. Conclusion The total case number of notifiable infectious diseases between January and May in 2021 was lower than those during the same periods in previous years, the incidence would continue to remain stable in this summer. It is predicted that the case numbers and the incidence intensities of brucellosis, HFMD, dengue and anthrax would continue to increase in this summer. The surveillance and early warning of these diseases should be strengthened.

目的 评估2021年全国夏季重点传染病疫情形势,为进一步做好夏季重点传染病监测与防控提供参考和指导.方法 根据我国传染病疫情报告信息管理系统、流感专病监测信息管理系统的监测数据,在对2021年1-5月全国法定传染病监测数据以及2017-2020年同期疫情形势进行分析基础上,采用专家会商法,研判我国2021年夏季重点传染病的疫情形势.结果 2021年截至5月23日,全国共报告法定传染病247万例,较2020年同期(260万例)下降5％;排除新型冠状病毒肺炎(COVID-19)后,报告发病数较2019年同期(426万例)下降42％,较2017-2019年同期平均水平(324万例)下降24％;死亡7162例,较2020年同期(11671例)下降39％,较2017-2019年同期平均(7639例)下降6％.布鲁氏菌病报告病例数(2.7万)较2020年同期上升73％,较2017-2019年同期平均上升70％,内蒙古布鲁氏菌病发病率自2017年开始迅猛上升,宁夏回族自治区、甘肃省自2018年呈上升趋势.手足口病报告病例数(43万例)和重症数(433例)较2020年同期分别上升985％和1070％.全国共报告登革热病例15例,较2020年同期(110例)下降86％.报告炭疽病例59例,较2020年同期(47例)略有增加.流行性感冒报告病例数(10.7万例)较2020年同期下降90％.2021年我国内地共报告11例人感染禽流感病例,较往年略有增加,均为散发.结论 2021年1-5月全国法定传染病疫情总体低于往年同期平均水平,夏季仍将继续维持总体平稳态势.预计夏季布鲁氏菌病、手足口病、登革热、炭疽的发病水平将呈现上升趋势,应加强对这些夏季重点传染病的监测预警.

The objective of this study was to construct a rapid, high-throughput, and biosafety-compatible screening method for Bacillus anthracis and Bacillus cereus based on matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). MALDI-TOF MS coupled to ClinProTools was used to discover MALDI-TOF MS biomarker peaks and generate a classification model based on a genetic algorithm (GA) to differentiate between different Bacillus anthracis and Bacillus cereus isolates. Thirty Bacillus anthracis and 19 Bacillus cereus strains were used to construct and analyze the model, and 40 Bacillus strains were used for validation. For the GA screening model, the cross-validation values, which reflect the ability of the model to handle variability among the test spectra, and the recognition capability values, which reflect the model's ability to correctly identify its component spectra, were all 100%. This model contained 10 biomarker peaks (m/z 3,339.9, 3,396.3, 3,682.4, 5,476.7, 6,610.6, 6,680.1, 7,365.3, 7,792.4, 9,475.8, and 10,934.1) used to correctly identify 28 Bacillus anthracis and 12 Bacillus cereus isolates from 40 Bacillus isolates, with a sensitivity and specificity of 100%. With the obvious advantages of being rapid, highly accurate, and highly sensitive and having a low cost and high throughput, MALDI-TOF MS ClinProTools is a powerful and reliable tool for screening Bacillus anthracis and Bacillus cereus strains.

Anthrax is a natural foci disease in Inner Mongolia, which poses a severe threat to public health. In this study, the incidence number, rate and constituent ratio were used to describe the epidemiological characteristics of anthrax in the region from 1956-2018. The molecular correlation and genetic characteristics of the strains were investigated using canonical single nucleotide polymorphisms (CanSNP), multiple-locus variable-number tandem repeat analysis (MLVA-15) and whole genome sequencing (WGS). The epidemiological characteristics of anthrax in Inner Mongolia have altered significantly. The incidence of anthrax has decreased annually without vaccination, and the regional distribution of anthrax gradually transferred from central and western regions to the eastern. Moreover, the occupation distribution evolved from multiple early occupations to predominated by farmers and herdsmen. This change is closely related to policy factors and to changes in the means of production and the living habits of the local population. This indicates that reformulating the control and prevention strategies is essential. Both A. Br. Ames and A. Br. 001/002 subgroups were the predominant CanSNP genotypes of Bacillus anthracis in Inner Mongolia. A total of 36 strains constituted six shared MLVA-15 genotypes, suggesting an epidemiological link between the strains of each shared genotype. The six shared genotypes ([GT1, 9, 11 and 15] and [GT8 and 12]) consisting of 2-7 strains confirmed the occurrence of multiple point outbreaks and cross-regional transmission caused by multiple common sources of infection. Phylogenetic analysis based on the WGS core genome showed that strains from this study formed an independent clade (C.V.), and they were positioned close to each other, suggesting a common origin. Further comparison analysis should be performed to ascertain the geographic origin of these strains.

目的 研究蜡样芽胞杆菌毒力基因在不同标本中的分布特征.方法 分离自环境监测标本(米粉、奶粉、土壤)和疾病相关标本(米饭、凉皮、眼内炎和肿瘤患者)的蜡样杆菌333株,PCR扩增蜡样杆菌11个毒力基因,包括溶血性BL基因(hblC、hblD、hblA、hblB)、非溶血性基因(nheA、nheB、nheC)、肠毒素FM基因和T基因(entFM、bceT)、细胞毒素K基因(cytK)和呕吐毒素相关基因(ces),统计不同标本菌株中毒力基因的携带数目和各毒力基因的携带率,方差分析和卡方检验比较毒力基因在不同标本中,尤其是在疾病相关标本与环境监测标本中的携带差异.结果 研究菌株携带毒力基因平均数目为5.97个,88.29％的菌株携带至少3个毒力基因,12.31％的菌株携带除ces外的所有基因.标本携带毒力基因数目从高到低依次为患者(8.75)、凉皮(8.20)、米饭(7.13)、土壤(6.22)、米粉(5.78)和奶粉(5.71).患者、凉皮分别与奶粉的基因数目两两比较有统计学差异显著性.菌株各毒力基因的携带率从高到低依次为非溶血性基因(89.19％)、entFM基因(79.88％)、bceT基因(49.85％)、溶血性BL基因(48.35％)、ctyK基因(47.75％)和ces基因(1.50％).溶血性基因在疾病相关标本中的携带率比环境监测标本高(x2 =8.230,P＜0.01),其余基因携带率则在两类标本中无统计学差异.环境监测标本中,土壤的溶血性基因携带率高于米粉和奶粉(x2=15.071,P＜0.01),非溶血性基因和entFM基因的携带率则低于后两者,检验值分别为(x2=9.603,P＜0.05)和(x2=21.634,P＜0.01).结论 蜡样杆菌毒力基因在不同标本中的分布,尤其是毒力基因数目和溶血性基因在疾病相关标本中较高的携带特点,为研究蜡样杆菌的致病性提供了一定的参考依据,具有一定的临床意义.

目的 筛选蜡样芽胞杆菌鉴定基因和快速检测毒力基因.方法 选择分离自食品和土壤的代表性蜡样芽胞杆菌共329株,聚合酶链式反应(PCR)方法检测gyrB和groEL基因的种特异性,检测毒力基因在菌株中的分布特征.基于检测结果,用多重PCR检测方案快速检测蜡样芽胞杆菌鉴定基因及其毒力因子.结果 在蜡样芽胞杆菌及其近缘芽胞杆菌中,除1株苏云金芽胞杆菌扩增阳性外,gyrB基因具有蜡样芽胞杆菌种特异性;而groEL基因在4种芽胞杆菌中均有扩增.6种毒力基因nheA、entFM、bceT、hblC、cytK和ces的携带率分别为84.19％、79.64％、49.24％、47.72％、47.11％和1.52％.选择nheA、hblC、entFM、ces、cytK和gyrB用于快速鉴定蜡样芽胞杆菌及其毒力基因,获得了双重PCR扩增体系(gryB和cytK)与4重PCR扩增体系(nheA、hblC、entFM和ces)的最佳检测方案.结论 筛选的蜡样芽胞杆菌鉴定基因和毒力基因能够全面、特异、简便、高效地检测蜡样芽胞杆菌,可为食品安全检测及快速诊断提供依据,在实际检验工作中具有良好的应用前景.

目的 对某校疑似炭疽疫苗菌株毒力恢复事件(事件)中,教学实验使用的炭疽芽孢杆菌毒力及其环境污染情况进行鉴定和调查,为合理处理该事件提供参考依据.方法 调查事件发生的情况、采集实验用培养物、冻存菌株和实验室环境样本.对实验用培养物进行噬菌体裂解和青霉素敏感试验鉴定;选取炭疽芽孢杆菌的rpoB基因和毒力相关的pagA和capC基因,应用TaqMan荧光探针法对采集样本进行检测.结果 实验用培养物的噬菌体裂解试验显示有明显的噬菌斑,青霉素敏感试验显示在青霉素纸片周围有明显的抑菌环,并且培养物和冻存菌株rpoB和pagA基因检测为阳性,capC基因检测为阴性;教学场所的环境样本rpoB、pagA和capC基因检测均为阴性.结论 该事件中实验用培养物和冻存菌株均为缺少capC基因的减毒炭疽芽孢杆菌,未发现毒力恢复情况;教学场所中无炭疽芽孢杆菌的污染.

目的 总结分析内蒙古自治区(内蒙古)炭疽暴发疫情中炭疽病例诊断方法的应用经验和问题,为炭疽预防控制工作提供参考.方法 用载玻片直接蘸取和无菌棉签擦取疑似炭疽病例皮损渗出液,同时采集疑似病例静脉血标本.涂片镜检、直接分离培养、肉汤增菌后分离培养炭疽菌、炭疽芽胞杆菌实时荧光定量PCR扩增(毒素质粒的pagA、染色体rpoB、荚膜质粒的cap)以及ELISA法检测双份血清炭疽抗体.结果 2018年8月,内蒙古通辽市疾病预防控制中心实验室共采集17例炭疽病例标本,采集时间距发病时间最短1d,最长16d,中位数为6d.15例可疑病例用过抗生素后采集标本(15/17,88.24％).从1份标本中分离到炭疽芽胞杆菌,分离阳性率为5.88％(1/17);实时荧光PCR检测17份标本,阳性率为41.18％ (7/17);ELISA检测保护性抗原抗体阳性率为83.33％ (10/12).结论 在最佳时间采集标本是疫情早期定性的关键.推荐炭疽疫情中应用快速灵敏的实时荧光PCR检测诊断方法,应采集所有可疑病例双份血清提高病例诊断率.

目的 评估2019年9月在我国大陆地区发生或者可能由境外输入的突发公共卫生事件风险.方法 根据国内外突发公共卫生事件报告及重点传染病监测等各种资料和部门通报信息,采用专家会商法,并通过视频会议形式邀请省(自治区、直辖市)疾病预防控制中心专家参与评估.结果 总体上,预计9月突发公共卫生事件的报告数将较8月略有上升.我国媒介伊蚊分布地区处于登革热高发期,本地病例将继续增多,Ⅰ类省份部分本地暴发疫情仍将持续,存在发生较大规模本地暴发疫情的风险,输入病例多且媒介密度较高的Ⅱ、Ⅲ类省份存在输入病例引发本地传播甚至出现暴发疫情的可能.手足口病将进入秋季流行期.霍乱仍会出现散发病例.炭疽处于高峰期,既往存在炭疽疫源地的西部和东北等地发生炭疽病例的可能性大.空肠弯曲菌感染所致格林-巴利综合征暴发事件可能会发生.食物中毒仍处于高发期.刚果民主共和国埃博拉病毒病疫情仍将持续发生,但输入我国的风险低.结论 需要对登革热、手足口病予以重点关注,对霍乱、炭疽、空肠弯曲菌感染与格林-巴利综合征、食物中毒、刚果民主共和国埃博拉病毒病予以一般关注.

On December 14, 2017, a faculty member of a university in Hunan Province reported that an anthrax vaccine strain might have recovered virulence during an undergraduate experiment and potential exposure could not be ruled out for the students involved. Upon receiving the case report, the CDC, health bureaus, and local governments at the county, prefectural, and provincial levels promptly organized experts in different fields (including epidemiologists, biosafety experts, and laboratory testing experts) for case investigation, evaluation, and response. As the investigation results showed, no virulence recovery was identified in the involved anthrax vaccine strain; and no contamination of Bacillus anthracis was detected at the involved areas. Thus, the university returned to normal functioning.

Background Anthrax is an acute zoonotic infectious disease caused by the bacterium known as Bacillus anthracis. From 26 July to 8 August 2015, an outbreak with 20 suspected cutaneous anthrax cases was reported in Ganquan County, Shaanxi province in China. The genetic source tracking analysis of the anthrax outbreak was performed by molecular epidemiological methods in this study. Methods Three molecular typing methods, namely canonical single nucleotide polymorphisms (canSNP), multiple-locus variable-number tandem repeat analysis (MLVA), and single nucleotide repeat (SNR) analysis, were used to investigate the possible source of transmission and identify the genetic relationship among the strains isolated from human cases and diseased animals during the outbreak. Results Five strains isolated from diseased mules were clustered together with patients’ isolates using canSNP typing and MLVA. The causative B. anthracis lineages in this outbreak belonged to the A.Br.001/002 canSNP subgroup and the MLVA15-31 genotype (the 31 genotype in MLVA15 scheme). Because nine isolates from another four provinces in China were clustered together with outbreak-related strains by the canSNP (A.Br.001/002 subgroup) and MLVA15 method (MLVA15-31 genotype), still another SNR analysis (CL10, CL12, CL33, and CL35) was used to source track the outbreak, and the results suggesting that these patients in the anthrax outbreak were probably infected by the same pathogen clone. Conclusions It was deduced that the anthrax outbreak occurred in Shaanxi province, China in 2015 was a local occurrence.

Using national surveillance data for 120,111 human anthrax cases recorded during 1955-2014, we analyzed the temporal, seasonal, geographic, and demographic distribution of this disease in China. After 1978, incidence decreased until 2013, when it reached a low of 0.014 cases/100,000 population. The case-fatality rate, cumulatively 3.6% during the study period, has also decreased since 1990. Cases occurred throughout the year, peaking in August. Geographic distribution decreased overall from west to east, but the cumulative number of affected counties increased during 2005-2014. The disease has shifted from industrial to agricultural workers; 86.7% of cases occurred in farmers and herdsmen. Most (97.7%) reported cases were the cutaneous form. Although progress has been made in reducing incidence, this study highlights areas that need improvement. Adequate laboratory diagnosis is lacking; only 7.6% of cases received laboratory confirmation. Geographic expansion of the disease indicates that livestock control programs will be essential in eradicating anthrax.

Anthrax toxins and capsules, which are encoded by genes located on pXO1 and pXO2, respectively, are major virulence factors of Bacillus anthracis. Our previous studies demonstrated that exposure to high-temperatures is unable to abolish the pXO1 plasmid of the Pasteur II strain, but the growth of the strain was obviously slower than that of the Sterne strain and wild-type virulent strain. To elucidate a potential regulatory mechanism of slowing growth, we employed comparative genome and bioinformatic analysis and revealed a unique SNP (G to T) at the 143135 bp position in pXO1 that is possibly involved in the mediation of growth of Pasteur II. However, the T to G mutation in groR did not result in any change of the amino acid sequence. A predominant nucleotide G existed at the 143135 bp in pXO1 of 100 wild-type B. anthracis isolates and 9 isolates documented in GenBank, whereas T replaced G in pXO1 of the Pasteur II strain. Further analysis indicate that the SNP is located in a gene between 143042 and 143173 bp, and that it encodes a small protein of 43 amino acids and is termed as a growth regulator (GroR). Site-directed mutagenesis and gene deletion demonstrates that groR regulates the growth and spore formation of B. anthracis. Our results indicate that the pXO1 plasmid is involved in the regulation of growth and spore formation in B. anthracis.