Detection and molecular typing of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks and in different patient samples from southwest Germany

The prevalence of different genospecies of Borrelia burgdorferi sensu lato in infected ticks could be a determinant for the risk of acquiring Lyme borreliosis (LB) and its clinical presentation. A total of 7373 ticks and 2761 samples from LB patients from the same area in southwest Germany were analyzed by PCR to assess the frequency of the occurrence of LB-associated genospecies. Fifteen percent of the tick samples and 19% of the human samples were found positive for the presence of B. burgdorferi sensu lato. Further identification of 1106 B. burgdorferi sensu lato positive tick samples by reverse line blotting and 125 positive patient samples by nested PCR using species-specific primers revealed the occurrence of B. afzelii, B. burgdorferi sensu stricto, B. garinii and B. valaisiana. Both single-species and mixed infections were noted and a similar distribution of the different genospecies was found in ticks compared with human samples. It was also the purpose of this study to obtain more information about a possible correlation between the distribution of Borrelia species and clinical syndromes of LB. Skin biopsies of 59 patients with acrodermatitis chronica atrophicans and cerebrospinal fluid samples from 78 patients with possible neuroborreliosis were analyzed. In conclusion, the distribution of the different genospecies in ticks is the decisive factor for the occurrence of the different Borrelia genospecies in samples from LB patients. Borrelia afzelii is the predominant genospecies in all kind of samples from the observed area and there seems to be no association of particular Borrelia genospecies with distinct clinical manifestations of LB.     

Genospecies of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks from the Autonomous Province of Trento, Italy

Sequences of the variable intergenic spacer region 5S (rrfA) 23S (rrlB) rRNA were used to identify Borrelia genospecies present in Ixodes ricinus nymphs collected from the Lamar Lakes area of the Province of Trento, Italy (overall prevalence=6.3%). Four genospecies were identified, one for the first time in this Province (B. valaisiana), and three which have been noted previously (B. afzelii, B. garinii, and B. burgdorferi s.s.). In order to compare the genetic variability of these genospecies in Trento with that at a European level, our 21 sequences (15 new haplotypes) and all appropriate European Borrelia sequences registered in GenBank (up to the end of 2004) were subjected to a phylogenetic analysis (for a total of 73 sequences and 43 haplotypes). Clusters of sequences representing the five main European genospecies (afzelii, garinii, burgdorferi s.s., valaisiana, lusitaniae) are well-supported. At least two other groups of haplotypes (genospecies) are suggested by our analysis; moreover, divergent evolution may be occurring in several genospecies. The maximum uncorrected pairwise differences between sequences within genospecies ranges from 1.5% (B. burgdorferi s.s.), to 2.3% (B. garinii and B. valaisiana) to 4.7% (B. afzelii), and are not correlated with geographical distribution. Within the Province of Trento, these values for the same genospecies are 1.5%, 2.3%, 0.9%, 1.9%, respectively. These high mutation rates within genospecies suggest that the sequencing of haplotypes should continue if we are to fully understand and monitor the evolution and epidemiology of Borrelia.     

我国莱姆病的流行病学和病原学研究

１９８７－１９９６年对２２个省市（市、区）的６０个县、区进行了莱姆病的调查研究。血清流行病学证实２２个省市（市、区）林区人群均存在莱姆病感染，感染率平均为５．０６％（１７２４／３４１０４）。病原学证实１７个省（市、区）存在莱姆病自然疫源地。１１个省（市、区）有典型病例存在。     

大兴安岭林区蜱和鼠中莱姆病螺旋体感染及其基因分型研究

目的 了解内蒙古大兴安岭林区蜱和鼠中伯氏疏螺旋体的感染及基因分型情况。方法 应用巢式PCR扩增蜱和鼠中伯氏疏螺旋体5S-23SrRNA间隔区片段，对阳性产物进行限制性片段长度多态性（RFLP）分析和单链构象多态性（SSCP）分析，RFLP分析显示特殊带型的样本测序分析。结果 检测全沟硬蜱1336只，293只阳性，阳性率为21．93％；森林革蜱144只，6只阳性，阳性率为4．17％；嗜群血蜱144只，未发现有伯氏疏螺旋体感染。检测鼠9种145只，感染伯氏疏螺旋体的4种5只，感染率为3．45％；其中检测8只棕背鼠平，2只阳性。RFLP分析及序列分析显示蜱中有B．garinii20047亚型、B．gariniiNT29亚型、B．afzelii基因型以及不同基因型或亚型伯氏疏螺旋体的混合感染；鼠感染的伯氏疏螺旋体包括B．garinii20047亚型和B．gariniiNT29亚型。SSCP分析结果显示带型多于36种。结论 大兴安岭林区蜱及鼠中均存在伯氏疏螺旋体的感染，其中全沟硬蜱的感染率较高；B．garinii型为主要基因型，且该地区伯氏疏螺旋体存在遗传多态性。单只蜱中存在同时感染不同基因型伯氏疏螺旋体的情况，人和宿主动物是否存在不同基因型伯氏疏螺旋体混合感染尚待进一步研究。全沟硬蜱和棕背鼾分别是该林区伯氏疏螺旋体的主要媒介和主要储存宿主。