Abstract:

Objective To investigate the natural progression of Borrelia burgdorferi infection among the human population in some natural foci in Xinjiang, China and the genotypes of B. burgdorferi. Methods In 2006, 119 human subjects, who were randomly selected from 1390 negative cases of 1406 individuals receiving a seroepidemiological survey of B. burgdorferi infection in the summer of 2002, as well as the 16 positive cases in the 2002 survey, were included in the study. Serum samples of each individual were collected in 2002 and 2006 and examined for the IgM and IgG to B. burgdorferi by Western blot, and a questionnaire survey was performed to investigate the frequency of manifestation of Lyme disease. In addition, urine samples were collected from the 135 subjects and examined by nest PCR to amplify 5S-23S rRNA intergenic spacer of B. burgdorferi;some of the PCR positive products were sequenced to determine the genotypes of B. burgdorferi. The PCR detection results were compared with the serological test results. Results Of the 1406 serum samples in 2002, 16 (1.14%) were positive for B. burgdorferi antibodies. In the 16 positive cases, 12 were positive for IgM, 2 were positive for IgG, and 2 were positive for both IgM and IgG. In 2006, 7 (43.75%) of the 16 positive cases in 2002 became seronegative, 4 IgM-positive cases became IgG-positive, and 5 cases remained IgM-positive. Of the 119 negative cases in 2002, 58 (48.74%) became seropositive, including 14 IgM-positive cases, 25 IgG-positive cases, and 19 IgM-and IgG-positive cases, and 2 cases had a confirmed diagnosis of Lyme disease. In 2006, 67 (49.63%) of the 135 subjects were positive for B. burgdorferi antibodies, including 58 newly found cases and 9 cases that remained positive since 2002. Asymptomatic IgG positive seroconversion rate was 34.07% (46/135) (in 2002, 4 IgM-positive cases became IgG-positive; in 2006, 25 negative cases became IgG-positive and 19 negative cases became IgM-and IgG-positive, and 2 cases had a confirmed diagnosis of Lyme disease). Only 3 (2.22%) of the 135 subjects developed Lyme disease. Of the 135 urine samples, 22 (16.30%) had positive results in PCR detection. The sequence analysis of 8 PCR positive products revealed that 7 of them were B. garinii and the other was B. afzelii. Conclusion Most cases of B. burgdorferi infection are asymptomatic among the human population in the natural foci of Xinjiang, and this infection rarely results in Lyme disease. The most and second most frequent genotypes of B. burgdorferi among Xinjiang population are B. garinii and B. afzelii.

Key words: Borrelia burgdorferi, Antibody, Sequence analysis, Genotype

摘要：

目的 探讨新疆部分自然疫源地自然人群感染莱姆病螺旋体的自然进程及感染莱姆病螺旋体的基因型情况。方法 在2002年夏季完成的1406人莱姆病螺旋体感染血清流行病学调查的基础上,2006年在上述1406人中的1390人阴性人群中,随机抽取119人,与2002年16例阳性(共计135人)为研究对象,在这两个时点收集的血清标本均应用蛋白印迹(Western blot,WB)方法检测抗Borrelia burgdorferi抗体IgM和IgG,并完成莱姆病表现频率调查问卷。同时留取135份尿液标本,应用巢式PCR扩增尿液标本中莱姆病螺旋体5S～23S rRNA间隔区片段,对部分阳性产物测序分析,确定莱姆病螺旋体的基因型,并将PCR检测结果与血清学的检测结果相比较。结果 2002年1406份血清标本中,抗体阳性16份,阴性1390份,阳性率为1.14%(16/1406)(16例中IgM阳性12例,IgG阳性2例,IgM、IgG均阳性者2例)。2006年上述16例抗体阳性的感染者中,有7例抗体转为阴性,阴转率为43.75%(7/16),4例由IgM阳性转为IgG阳性,IgM持续阳性5例,2002年抗体阴性的119人中,2006年有58例抗体转为阳性(IgM阳性14例,IgG阳性25例,IgM和IgG均阳性的19例),阳转率为48.74%(58/119),确诊为莱姆病2例。2006年抗B. burgdorferi 抗体总阳性率为49.63%(67/135)(2006年阳性58例＋2002年阳性9例)。无症状IgG血清转换率为34.07%(46/135)(2002年IgM阳性转换为IgG 阳性的4例＋2006年IgG阳性的25例、IgM和IgG均阳性的19例,其中确诊莱姆病2例);3例发展为莱姆病(2.22%)。135份尿液PCR检测,阳性22份,阳性率为16.30%(22/135)。8份PCR阳性结果测序分析显示7份为B. garinii,1份为B. afzelii 基因型。结论 新疆自然疫源地人群莱姆病螺旋体感染大多为隐性感染,自然进程较为良性,临床莱姆病少有发生。新疆人群莱姆病螺旋体感染基因型主要为B. garinii,其次是B. afzelii。

关键词: 莱姆病螺旋体, 抗体, 序列分析, 基因型