安徽省六安市立克次体病血清学诊断和分子流行病学分析

Serological diagnosis and molecular epidemiological analysis of rickettsiosis in Lu’an,Anhui Province,China

目的 2017年5月-2021年11月安徽省六安市霍山县医院收治的发热伴皮疹病例数量增加,通过流行病学和临床特征分析,查明其病因,为发热伴皮疹预防控制提供科学依据。方法 对发热伴皮疹患者进行流行病学调查,详细询问其病史情况,调取其临床病历。采集患者入院时的急性期和恢复期血清,使用间接免疫荧光法检测血清中无形体、伯氏疏螺旋体、东方体、埃立克体、立氏立克次体和斑疹伤寒立克次体的IgG抗体滴度,通过恢复期血清IgG抗体滴度4倍增长,判定为感染该病原体;急性期血清经立克次体序列测定,所得序列与GenBank公布序列比对分析,根据同源性确定引起该起疫情的病原体。结果 病例急性期血清无形体、伯氏疏螺旋体和斑疹伤寒立克次体IgG抗体均为阴性;急性期血清中立氏立克次体IgG阳性率为51.52%(68/132),恢复期阳性率为89.19%(33/37),患者恢复期血清中IgG抗体滴度与急性期相比,增长均>4倍。立克次体ompA序列进化树分析表明该立克次体与我国云南省发现的Candidatus Rickettsia jingxinensis最为接近。结论 六安市发热伴皮疹病例经血清学诊断为斑点热立克次体感染。

Objective From May 2017 to November 2021,there was an increased number of cases of fever with rashes admitted to Huoshan County Hospital in Lu’an City,Anhui Province,China.The aim of the study is to find out the etiology of the patients through epidemiological and clinical characteristic analysis,so as to provide a scientific basis for the prevention and control of the febrile illness with rashes.Methods An epidemiological investigation was carried out on the cases of fever with rashes through inquiring their medical histories and reviewing their medical records.The acute sera at admission and convalescent sera were collected from the patients to examine IgG antibody titers to Anaplasma,Borrelia burgdorferi,Orientia,Ehrlichia,Rickettsia rickettsii,and R.typhi using indirect immunofluorescence assay.An infection of a pathogen was determined by a 4-fold increase of the serum IgG antibody titer to the pathogen between the acute serum and the convalescent serum.The etiologic agent causing the outbreak was further identified by PCR amplification and DNA sequences of the rickettsial genes from acute serum.Results The IgG antibodies to Anaplasma,B.burgdorferi,and R.typhi were all negative in the acute sera of the patients.The positive rate of serum IgG antibodies to R.rickettsii was 51.52%(68/132)in the acute sera and 89.19%(33/37)in the convalescent sera.In the paired sera,the IgG titer had more than four time increase in the acute sera than in the convalescent sera.Phylogenetic analysis with the Rickettsia ompA sequence indicated that the etiologic agent formed a monoclade with newly identified Candidatus R.jingxinensis in Yunnan,China.Conclusion The febrile cases with rashes in Lu’an were serologically diagnosed as spotted fever rickettsial infection.