河北省首次实验室确诊恙虫病东方体Kawasaki感染病例

目的对2017年7月13日恙虫病疑似病例进行实验室检测和分析，了解河北省恙虫病基因型的流行情况。 方法对疑似病例进行流行病学调查，详细询问其病史情况；采集入院时的急性期血清以及2周后的恢复期血清，使用间接免疫荧光法检测血清中的IgG抗体滴度，进行血清抗体滴度分析；提取血液总DNA，采用PCR方法进行基因型鉴定，运用最大似然法构建系统进化树，确定该恙虫病东方体基因型。 结果 病例血清中汉坦病毒、新型布尼亚病毒、登革热病毒、伤寒和副伤寒杆菌、无形体、埃立克体以及立克次体抗体均为阴性；急性期血清中抗恙虫病东方体IgG滴度为1∶64，恢复期血清中的滴度为1∶256； PCR扩增获得目的片段测序比对结果显示与恙虫病东方体Kawasaki型序列相似度最高，达到99%；该毒株与已知恙虫病东方体Kawasaki具有最近亲缘关系。 结论 河北省首次实验室确诊存在恙虫病东方体Kawasaki基因型。

Laboratory confirmation of Orientia tsutsugamushi (Kawasaki strain) first identified in Hebei province

ObjectiveTo investigate the circulation of Orientia tsutsugamushi in Hebei province through the laboratory examination of a suspected scrub typhus case detected in Baoding of Hebei province on July 13, 2017. MethodsThe acute phase serum and convalescent phase serum of the case were collected at day 0 and day 14, respectively. The IgG titers of anti-O. tsutsugamushi in serum were analyzed by using indirect immunofluorescence assay (IFA). The genomic DNA was extracted using DNA extraction kit, and Rickettsiales was identified in this sample by amplifying the Rickettsiales 16S rRNA (rrs) and tsa56 genes. Phylogenetic trees were reconstructed using the maximum likelihood (ML) method implemented in PhyML to determine the genotype of the strain. ResultsThe highest body temperature of the case with fever of unknown origin was 39℃. The detections for serum antibodies of 9 pathogens, including hantavirus, severe fever with thrombocytopenia syndrome virus, dengue virus, Anaplasma sp., Ehrlichiasp., Rickettsia sp., Salmonella typhi and Salmonella paratyphi and O. tsutsugamushi, were conducted, but only the result of O. tsutsugamushi detection was positive. The titers of IgG against O. tsutsugamushi was 1∶64 in the acute phase serum and 1∶256 in the convalescent phase serum. PCR amplification indicated that the rrs sequence from the strain from the case showed high similarity with O. tsutsugamushi(Kawasaki strain) (99.0%). Meanwhile, phylogenetic analysis of the rrs and tsa56 gene sequences revealed that the sequences from the case had a close relationship with Orientia tsutsugamushi(Kawasaki strain). ConclusionOrientia tsutsugamushi(Kawasaki strain) was identified for the first time in the laboratory in Heibei province.