Objective:Severe fever with thrombocytopenia syndrome (SFTS), an emerging infectious disease with substantial mortality, was first reported in China in 2009 and subsequently became endemic to South Korea, Japan, Vietnam, and the United Arab Emirates. Despite growing concerns about its transmission dynamics, the potential for human-to-human transmission through close physical contact remains inadequately explored in the literature. Methods:We conducted comprehensive epidemiological investigations of the initial cases of SFTS. In these investigations, real-time fluorescent reverse transcription polymerase chain reaction (RT-PCR) was used to analyze blood samples, followed by whole-genome sequencing (WGS) for phylogenetic tree construction. Results:Our analyses identified one potential index case (Case A) and one confirmed case (Case B), both of which tested positive for SFTS virus (SFTSV) nucleic acid. Notably, we observed an 8.65 % positive rate for SFTSV nucleic acid in Haemaphysalis longicornis ticks near Case A's residence. Additionally, the only potential exposure route for Case B appeared to be close physical contact with Case A. Genetic sequencing indicated high nucleotide homology (ranging from 99.63 % to 99.91 %) between the SFTSV strains isolated from both cases. Conclusions:Collectively, our study further demonstrated that close intimate contact may serve as a significant mode of SFTSV transmission among humans. This finding underscores the importance of enhancing awareness and implementing preventive measures among patients, healthcare providers, and relevant public health personnel regarding the human-to-human transmission of SFTS, contributing to more targeted public health strategies in SFTS-endemic regions, particularly in areas with low endemicity levels.

Background Severe Fever with Thrombocytopenia Syndrome (SFTS) is an emerging infectious disease that poses a significant threat to public health, given its high fatality rate and potential for person-to-person transmission. Caused by the SFTS virus (SFTSV), a novel bunyavirus first identified in central and eastern China, SFTS has drawn increasing attention in recent years. Methods To gain an updated and in-depth insight into the epidemiological features of SFTS in eastern China, this study collected all confirmed SFTS cases in the year of 2024 from Yangzhou, Jiangsu Province. A total of 33 laboratory-confirmed SFTS cases were included in the analysis; after obtaining their complete viral genome sequences through sequencing, an epidemiological investigation was conducted. Additionally, a phylogenetic tree was constructed using MEGA-X software. Results Our findings revealed that the number of SFTS cases in Yangzhou showed an overall upward trend over the study period, with only a slight decline in the past three years. The laboratory confirmation rate stood at approximately 64.4%. Most SFTS cases were sporadic rather than clustered. Notably, the mortality rate exhibited a positive correlation with age-rising as patients’ age increased. Conclusions In summary, this study systematically analyzed laboratory-confirmed SFTS cases in Yangzhou. The results suggest that the diagnostic and reporting criteria for SFTS need further optimization and standardization. Such improvements would facilitate a more accurate understanding of the disease’s epidemiological characteristics and provide scientific evidence to support SFTS prevention and control efforts.

Introduction: China implemented a dynamic zero-COVID strategy to curb viral transmission in response to the coronavirus disease 2019 (COVID-19) pandemic. This strategy was designed to inhibit mutation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for COVID-19. This study explores the dynamics of viral evolution under stringent non-pharmaceutical interventions (NPIs) through real-world observations. Methodology: Our analysis encompassed all polymerase chain reaction (PCR)-confirmed COVID-19 cases (n = 780) from two consecutive outbreaks occurring in July to August 2021. Epidemiological investigations and in-depth viral genome analyses were conducted to determine the sources of infection and the inter-outbreak linkages. Results: The outbreaks likely originated via contaminated objects from an imported COVID-19 case to local airport cleaners. Most patients presented clinically mild symptoms. All viral genomes clustered into a single clade, with genomes from the subsequent Yangzhou outbreak forming a distinct branch, diverging from those of the initial Nanjing outbreak. Compared to the Wuhan-Hu-1 strain, the Delta variants isolated from the imported case and early local cases in Nanjing had 35 nucleotide mutations and three deletions. Various single nucleotide variant (SNV) combinations were observed in subsequent transmissions, with NPIs accounting for the termination of 67.2% (92/137) of SNV combinations. Stringent implementation of NPIs resulted in a greater number of terminated SNV combinations than emerging ones. Additionally, vaccination of cases was associated with SNV combination termination. Conclusions: This study underscores the significant role of NPIs in preventing the accumulation of SARS-CoV-2 mutations.

Objective To investigate the drug resistance phenotype, drug resistance genes and molecular characteristics of clinical isolates of Staphylococcus aureus in Yangzhou from 2016 to 2020. Methods A total of 71 strains of clindamycin resistant Staphylococcus aureus were collected.Molecular typing of the strains was performed using multilocus sequence typing（MLST） and SNP.Antimicrobial minimal inhibitory concentrations were detected by the method of microdilution broth.Different resistance genes were detected. Results A total of 71 strains of clindamycin resistant Staphylococcus aureus were collected in this study, of which 42 strains（59.15%） were inherently resistant and 29 strains（40.85%） were induced resistant; 44 strains（61.97%） were found to be methicillin resistant Staphylococcus aureus（MRSA）.Among the 71 strains, 18 ST types were found, and the detection rates of mecA and ermB in ST59 strain were higher than those in other ST types.Among the clustered strains, CC59 was inherently resistant. Conclusion The clinically isolated Staphylococcus aureus in Yangzhou has severe drug resistance, especially the resistance to clindamycin.CC59 clone group carries many drug resistance genes, and all of them are MRSA.This study provides reliable data for clinical selection of appropriate drugs and further investigation of the prevalence of clindamycin-resistant strains.

Objective To investigate the distribution of avian influenza virus in the poultry related environment and the infection of avian influenza virus in population with occupational exposure to avian influenza virus,and provide evidence for the prevention and control of human avian influenza in this area.Methods The poultry related environment samples,the respiratory tract samples of pigs and the serum of population with occupational exposure to poultry and pigs were collected. Real time fluorescence quantitative PCR was used to detect the nucleic acid of influenza A virus in the poultry related environment samples and the respiratory tract samples of pigs. The positive samples were tested for nucleic of subtype H5,H7,H9,N1,N2,N6 and N9. The antibodies to influenza A（H5N6）,（H7N9）and（H9N2）viruses in the serum of population with occupational exposure were detected by erythrocyte agglutination inhibition test（HI）. Results Avian influenza surveillance in poultry-related external environment,a total of 1 196 samples were collected from2019 to 2021,and the positive rates of Flu A,H5,H9,N1,N2 and N6 were 12.29%（147/1 196）,2.17%（18/1 196）,11.62%（139/1 196）,0.33%（4/1 196）,11.79%（141/1 196）and 3.26%（39/1 196）,H7 and N9 subtypes were not detected. Two or more HA or NA subtypes of AIV were detected simultaneously in 35cases,with a positive rate of 2.93%（35/1 196）. There were significant differences in the positive rate of AIV in different years,monitoring sites and sample types（χ~2=118.28,163.74,285.74,P＜0.05）. AIV has the highest positive detection rate in 2021,reaching 30.63%（83/271）;among the four types of surveillance sites,AIV is highly prevalent in urban and rural live poultry markets,with a detection rate of 24.95%（126/505）.Among the six types of samples,the AIV positive rate of other types of environmental samples,wiped specimens on the cutting board surface of slaughtered or placed poultry meat,and sewage from washing poultry exceeded 50%. No AIV positive was detected in 180 samples of porcine respiratory tract. 553 samples of serum samples from occupationally exposed groups such as poultry and pigs were monitored,and no H5,H7,H9 avian influenza antibodies were detected. Conclusion The positive rate of avian influenza virus in poultry related environment in Yangzhou is high,the AIV types are diverse,the genetic recombination is prone to occur,and the risk of infecting people is high. Therefore,comprehensive prevention and control measures should be actively taken to reduce the positive detection rate of avian influenza in the external environment of the region and reduce human infection risk.

目的 了解扬州市近年来流感病原学流行趋势,为制定科学防控措施提供依据.方法 采用描述性流行病学方法,对2011-2021年扬州市流感样病例(ILI)病原学监测结果进行统计分析.结果 2011-2021年,全市3家哨点医院门诊和急诊累计就诊6 874 200人次,其中ILI为446 186人次,ILI％为6.49％,各年ILI％差异无统计学意义(x2=110.00,P=0.23).＜15岁儿童为ILI主要发病人群(占80.50％),≥60岁组占比最低(4.86％),各年龄组ILI分布差异有统计学意义(x2=15 021.26,P＜0.01).采集检测ILI咽拭子样本35 372份,核酸阳性率为10.50％,各年阳性率为0.31％～24.82％,差异有统计学意义(x2=35 764.91,P＜0.01).不同病毒型别中,甲型H3型最多(占31.66％),其次是乙型Victoria系(占28.89％),各年优势毒株轮流更替.ILI每周报告数、ILI％与病毒阳性率变化趋势基本吻合(rs=0.40、0.36,P值均＜0.05).结论 扬州市流行毒株主要是甲型H3、甲型HIN1pdm和乙型轮流交替.流感流行高峰到来前需加强流感监测并适当扩大采样.

Objective To analyze the epidemic characteristics of varicella and the genetic characteristics of varicella zoster virus（VZV） in Yangzhou in 2021,and to provide a theoretical basis for the scientific prevention and control of varicella in Yangzhou. Methods Descriptive epidemiological analysis was carried out on the varicella outbreaks reported in Yangzhou in 2021.Throat swabs or herpes fluid samples from varicella cases in 2021 were collected, and the viral nucleic acid was detected by real-time fluorescent quantitative PCR.The genotype and evolutionary relationship of the virus strain were determined according to the 6 SNPs in the ORF22 gene fragment sequence. Results In 2021,there were 20 varicella outbreaks in Yangzhou, involving 147 cases, all of which occurred in kindergartens and primary and secondary schools, and the peak incidence was in the age group of 4-7 years old.The high incidence time of the outbreaks was from May to July, and from November to January of the next year.The varicella vaccination rate of the cases was low, and all were 1-dose vaccination.The gene sequencing results of 8 samples were J/clade 2,and 3 of them had A-C synonymous mutation at position 37 997 in ORF22 sequence. Conclusion In 2021,varicella outbreaks in Yangzhou occurred mainly in kindergartens and schools.Preschool children are susceptible, all of which are caused by J/clade 2 varicella-zoster virus.It is suggested to strengthen the monitoring and management of the varicella epidemic situation in schools in the city, and at the same time incorporate the varicella vaccine into the routine immunization program of the city and strengthen 2 doses of varicella vaccination.

Kidney injury is common in patients with Coronavirus Disease-19 (COVID-19). In this study, 49 patients with Omicron associated kidney injury were included, 38 of whomperformed renal biopsy. Patients were divided into 2 groups: Group A for patients developing kidney injury afterSARS-CoV-2 infection and Group B for patients with aggravated renal insufficiency after SARS-CoV-2 infection. The clinical, pathological and prognostic characteristicsof the patients and theirC3 levels were observed.In our center, the clinical diagnoses of patients with COVID-19 associated kidney injury were mainly acute kidney injury(AKI), chronic kidney disease(CKD) and nephrotic syndrome(NS); while the pathological diagnoses were mainly IgA nephropathy(IgAN)、focal segmental glomerulosclerosis(FSGS) and membranous nephritis(MN).80% of COVID-19 associated nephropathy (COVAN) patients had normal serum C3 complement level, and a few patients had increased or decreased C3 level. In renal tissue, C3 deposits were observed in 68.4% of patients.29% of patients experienced deterioration of renal function after treatment, but no patients developed to end-stage renal disease (ESRD). Among all of them, one case presenting with thrombotic microangiopathy (TMA) had a more severe renal pathological lesion and poorer prognosis. We observed differences of clinical and pathological features of patients with COVID-19associated kidney injury between races, regions and virus variants. Asian patients with Omicron associated kidney injury have milder kidney injury and a better renal prognosis.

Background:With the continuous progress of the epidemic of coronavirus disease 2019 (COVID-19) infection and the constant mutation of the virus strain, reinfection occurred in previously infected individuals and caused waves of the epidemic in many countries. Therefore, we aimed to explore the characteristics of COVID-19 reinfection during the epidemic period in Yangzhou and provide a scientific basis for assessing the COVID-19 situation and optimizing the allocation of medical resources.Methods:We chose previously infected individuals of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reported locally in Yangzhou city from January 2020 to November 30, 2022. A telephone follow-up of cases was conducted from February to March 2023 to collect the COVID-19 reinfection information. We conducted a face-to-face survey on that who met the definition of reinfection to collect information on clinical symptoms, vaccination status of COVID-19, and so on. Data were analyzed using SPSS 19.0.Results:Among the 999 eligible respondents (92.24% of all the participants), consisting of 42.28% males and 57.72% females, the reinfection incidence of females was significantly higher than that of male cases (χ2 = 5.197, P < 0.05); the ages of the respondents ranged from 1 to 91 years, with the mean age of 42.28 (standard deviation 22.73) years; the most of the sufferers were infected initially with Delta variant (56.88%), followed by the Omicron subvariants BA.1/BA.2 (39.52%). Among all the eligible respondents, 126 (12.61%) reported COVID-19 reinfection appearing during the epidemic period, and the intervals between infections were from 73 to 1,082 days. The earlier the initial infection occurred, the higher the reinfection incidence and the reinfection incidence was significantly increased when the interval was beyond 1 year (P < 0.01) .119 reinfection cases (94.4%) were symptomatic when the most common symptoms included fever (65.54%) and cough (61.34%); compared with the initial infection cases, the proportion of clinical symptoms in the reinfected cases was significantly higher (P < 0.01). The reinfection incidence of COVID-19 vaccination groups with different doses was statistically significant (P < 0.01). Fewer reinfections were observed among the respondents with three doses of COVID-19 vaccination compared to the respondents with two doses (χ2 = 14.595, P < 0.001) or without COVID-19 vaccination (χ2 =4.263, P = 0.039).Conclusion:After the epidemic period of COVID-19, the reinfection incidence varied with different types of SARS-CoV-2 strains. The reinfection incidence was influenced by various factors such as virus characteristics, vaccination, epidemic prevention policies, and individual variations. As the SARS-CoV-2 continues to mutate, vaccination and appropriate personal protection have practical significance in reducing the risk of reinfection.

Objective To understand the transmission and evolution characteristics of methicillin-resistant Staphylococcus aureus (MRSA) isolated from the blood of ICU patients. Method We collected three strains of Staphylococcus aureus from different periods in the ICU of a certain hospital, and conducted drug sensitivity experiments using a fully automated bacterial drug sensitivity identification instrument. Molecular typing and analysis of resistance and virulence genes were performed on the entire genome sequences of three MRSA strains. Results Three strains of Staphylococcus aureus were identified as MRSA, and were resistant to erythromycin, oxacillin, levofloxacin, tetracycline, gentamicin, penicillin, and cefoxitin. The typing results showed that all strains were SCCmec Ⅱ-ST5 type. The annotation results show that S01 carries 6 drug resistance genes, namely blaZ, mecA, aac(6'')-Ieaph( 2'''')-Ia, lnuA, tetK, ermA. S02 and S03 carry 7 drug resistance genes, namely blaZ, mecA, aac(6'')-Ie-aph (2'''')-Ia, lnuA, tetK, ermA, ermC. Conclusion S03, S02, and S01 are highly homologous and carry more resistance genes. It is recommended that hospitals strengthen the concept of sterility among medical staff and disinfect the environment to control transmission.

Aim: This study aimed to establish a simple whole-genome sequencing method for respiratory virus type A (RSVA) used in genomic epidemiological studies. Methods: Multiple primers were designed to amplify overlapping amplicons specific to RSVA. The amplicons were sequenced using Illumina and Nanopore sequencing platforms and the sequencing performances of the two platforms were also compared. Results: The study shows that the developed method could recover almost full genomes of RSVA when Ct values were less than 33 for clinical samples. Conclusion: In this study, a whole-genome sequencing method was developed for RSVA based on multiplex PCR.

Objective:To understand the pollution status of avian influenza virus in environment in Yangzhou city during 2012-2020, so as to provide the basis for the prevention and control of avian influenza in Yangzhou city.Methods:The environmental samples in Yangzhou from 2012 to 2020 were collected to detect nucleic acid of avian influenza virus by real-time fluorescent PCR. Excel 2016 and SPSS 22.0 software were used for data summary and statistical analysis.Results:A total of 270 FluA positive specimens were detected from 3 537 environmental samples, with an overall positive rate of 7.63%. The number of positive samples of H5, H7, H9, and mixed infection were 14, 3, 158 and 95, respectively. There were statistically significant differences in the positive rates in different years ( x2=37.06, P<0.01), different months ( x2=97.80, P<0.01), different regions ( x2=52.36, P<0.01), different monitoring sites ( x2=330.67, P<0.01) and in different specimen types ( x2=371.16, P<0.01 ). Conclusions:There existed avian influenza virus contamination in environment in Yangzhou and H9 subtype and mixed contamination were predominant. The risks were mainly winter and spring, and live poultry markets in urban and rural areas.

目的 分析扬州地区住院肺炎患者呼吸道病原监测结果,了解呼吸道病毒流行情况.方法 收集2017—2020年扬州市住院肺炎患者咽拭子样本1479例,采用荧光聚合酶链反应(PCR)检测5种呼吸道病毒,并对结果进行分析.结果 1479例咽拭子样本中,阳性195例(13.18％),其中2种病毒混合感染7例(0.47％);检出率居前3位的分别为流感病毒(5.54％)、呼吸道合胞病毒(2.63％)、人肠道病毒(1.89％).2017年呼吸道病毒感染高峰集中在3～5月和11～12月,2018年集中在7月和9月,2019年集中在1～3月和12月,2020年集中在9月.女性患者阳性检出率高于男性(χ2=6.26,P<0.05);0～6岁儿童阳性检出率最高(χ2=15.87,P<0.05).呼吸道病原谱构成与性别无关(χ2=7.68,P>0.05);不同年份和不同年龄组病原谱构成差异有统计学意义(χ2值分别为6.26、27.33,P<0.01).结论 2017—2020年,扬州地区住院肺炎患者呼吸道病毒流行季节及病原谱构成每年均有所不同,主要病原为流感病毒、呼吸道合胞病毒,0～6岁儿童为易感人群,女性感染呼吸道病毒可能更易进展为肺炎.应加强呼吸道病原监测,流感病毒和呼吸道合胞病毒是呼吸道疫情防控的重点.

近年来,我国社会与经济快速发展,食品安全问题成了人民群众关注的焦点.因此,在发展过程中,有关部门为了提高食品安全质量,应用食品微生物检测技术,避免流入市场的食品出现安全问题.那么,食品微生物检测技术及其质量控制的要点有哪些呢?本文就这一问题进行综述.

Abstract Within the local outbreak period of SARS-CoV-2 Delta variant in Nanjing and Yangzhou, China, we analyzed the mutation process of the Delta variants in 520 cases, as well as the production, spread and elimination of new mutant strains under the non-pharmaceutical interventions (NPI) strategy. The investigation on distribution of COVID-19 cases and phylogenetic analysis of SARS-CoV-2 genome sequences attributed to tracking the transmission chains, transmission chains were terminated by the isolation of the COVID-19 patients and quarantine of close-contracts, suggesting the importance of NPI in prompting some mutations to disappear and stopping the transmission of new variants. Dynamic zero-Covid strategy has been implemented successfully to against the second-largest local epidemic caused by an imported COVID-19 case in China.

目的 分析扬州市新型冠状病毒肺炎(COVID-19)无症状感染者的流行病学特征.方法 以扬州市2020年1月21日-2月29日发现的COVID-19无症状感染者为研究对象,收集流行病学、实验室检测、暴露情况等资料.结果 扬州市14例COVID-19无症状感染者平均年龄为38.7岁,末次暴露到新型冠状病毒核酸检测阳性的平均时间为13.8 d,92.9％为COVID-19确诊病例的暴露后感染,85.7％为COVID-19确诊病例的家庭成员、亲戚等密切接触者.结论 COVID-19无症状感染者以青壮年为主,主要来源于COVID-19确诊病例的密切接触者排查和聚集性疫情调查.及时开展密切接触者的排查和采样,规范密切接触者的管理,能减少COVID-19无症状感染者可能造成的疫情扩散,减少重症、危重症病例.COVID-19无症状感染者解除医学观察后,需开展2～4周的健康监测.

目的 对扬州市报告的22例新型冠状病毒肺炎(COVID-19)确诊病例的呼吸道样本核酸检测结果及其相关因素进行分析,为COVID-19的防控提供依据.方法 对确诊病例进行随访,连续5周采集咽拭子并进行核酸检测,收集基本资料,用生存分析法对数据进行统计分析.结果 病例发病后1～2d、3～4d、5～7d的病毒阳性率为100％、100％、66.67％.所有病例平均核酸检测阳性时间为16.32 d,其中普通型为18.50 d,轻型为13.70 d,对二者的阳性率进行Log-rank检验,差异有统计学意义(χ2=4.36,P=0.037).多因素COX回归分析显示:病例类型(OR=0.19,95％CI:0.06～0.61)、发病-就诊时间(OR=0.70,95％CI:0.55～0.88)对病例的核酸检测阳性时间有影响.结论 确诊病例发病后1周内呼吸道标本阳性检出率高,轻型的核酸检测较普通型病例阳性时间短,及时就诊使用药物后可能会缩短病例的核酸检测阳性时间.

目的 探索扬州市小学生札如病毒感染所致急性胃肠炎暴发疫情的特点.方法 对札如病毒感染所致的急性胃肠炎聚集性疫情进行现场流行病学调查,分析札如病毒感染的临床症状、疫情传播危险因素;采集病例标本进行札如病毒核酸检测,对检测阳性的病例开展随访观察,探索札如病毒感染的排毒期;采集未发病的密切接触者标本分析隐性感染情况.结果 两起札如病毒感染的聚集性疫情共报告病例30例,临床表现以呕吐症状为主,发生率为93.33％,病例排毒期3～19 d,平均为11.12 d,隐性感染率为26.32％,札如病毒感染的危险因素为暴露于呕吐物或粪便一米以内(OR=12.94,95％CI:1.19～140.37);保护因素是就餐前洗手(OR=0.064,95％CI:0.007～0.56).结论 札如病毒感染的主要症状为呕吐,隐性感染率高,排毒期长,容易在小学校园等儿童聚集的场所引起聚集性疫情,暴露于呕吐物或粪便一米以内是札如病毒感染的危险因素,就餐前洗手可以减小札如病毒感染的风险.

目的 了解扬州市性病门诊男性就诊者高危行为模式及性病感染状况,制定有效的艾滋病性病防治策略.方法 2010年-2015年每年4月-6月哨点监测期间对前来性病门诊就诊的男性就诊者进行问卷调查,并采集静脉血进行HIV、梅毒和丙型肝炎血清学检测.结果 共调查性病门诊男性就诊者2 436人,HCV抗体阳性率为0.37％;TP抗体阳性率为12.60％;HIV抗体阳性率为0.82％.近1年性病患病率达24.96％,其中沙眼衣原体、尖锐湿疣和淋病患病数较多.近3个月高危行为发生率为61.90％.结论 本市性病门诊就诊者HIV、HCV感染率仍维持在较低水平,梅毒感染率较高.近1年内性病感染率较高,高危行为普遍存在,需积极采取有效的干预措施来控制艾滋病在性病患者中的蔓延扩散.

目的 探讨扬州市广陵区食品和公共场所从业人员沙门菌感染情况与血清型和分子分型特征.方法 2017年采集食品和公共卫生服务行业从业人员肛拭子标本,进行肠道致病菌的分离培养,对分离株进行血清学分型,再以脉冲场凝胶电泳(PFGE)进行分子分型和聚类分析.结果 2017年共采集肛拭子标本22 522份,检出沙门菌34株,检出率0.15％;男性0.10％,女性0.18％,差异无统计学意义(x2=2.15,P=0.14);夏秋季检出率(0.24％)高于冬春季(0.021％),差异有统计学意义(x2=16.9,P＜0.01).分离株以C1群最多(占35.29％),其次为B群(占32.35％);以里森沙门菌(占17.64％)和鼠伤寒沙门菌(占11.76％)为优势株.将血清凝集能分型的33株沙门菌进行PFGE分型分析,检出30个型别(P1～P30),其中3株为P29型、2株为P30型,上述5株相似度为85.42％,具有高度同源性;分离出的6株里森沙门菌中5株相似度相似度为60.56％,B群中的2株和E4群中的1株相似度为64.85％、C1群中的2株相似度为69.70％,均为相似菌株;其余型别相似度＜50％,为流行病学不相关.结论 2017年扬州市广陵区食品从业人员沙门氏血清型以C1群和B群为主.优势株为里森沙门菌、鼠伤寒沙门菌.菌株PFGE带型较分散.