Prevalence and diversity of Lyme borreliosis bacteria in marine birds

A potential role of seabirds in spreading Lyme disease (LB) spirochetes over large spatial scales was suggested more than 10 years ago when Borrelia garinii was observed in marine birds of both hemispheres. Since then, there have been few studies examining the diversity of Borrelia spp. circulating in seabirds, or the potential interaction between terrestrial and marine disease cycles. To explore these aspects, we tested 402 Ixodes uriae ticks collected from five colonial seabird species by amplification of the flaB gene. Both the average prevalence (26.0%+/-3.9) and diversity of LB spirochetes was high. Phylogenetic analyses grouped marine isolates in two main clades: one associated with B. garinii and another with B. lusitaniae, a genospecies typically associated with lizards. One sequence also clustered most closely with B. burgdorferi sensu stricto. Prevalence in ticks varied both among seabird species within colonies and among colonies. However, there was no clear association between different Borrelia isolates and a given seabird host species. Our findings indicate that LB spirochetes circulating in the marine system are more diverse than previously described and support the hypothesis that seabirds may be an important component in the global epidemiology and evolution of Lyme disease. Future work should help determine the extent to which isolates are shared between marine and terrestrial systems.     

Prevalence of Borrelia burgdorferi sensu lato genospecies in host-seeking Ixodes ricinus ticks in selected South Bohemian locations (Czech Republic)

In selected localities of Ceské Bud?jovice and Cesky, Krumlov districts, well known by stable high incidence of tick-borne encephalitis (TBE) human cases but with low incidence of Lyme borreliosis, monitoring of Borrelia burgdorferi sensu lato (s.l.) in Ixodes ricinus ticks was performed. Research was also aimed at the spread of I. ricinus to mountain areas of this region (National Park Sumava), as well as at investigating this tick for B. burgdorferi s.l. genospecies and TBE virus infection. Altogether 498 nymphs, 88 females and 11 males of I. ricinus from lower locations and 58 nymphs from mountain locations (760-1080 m above sea level) were tested by polymerase chain reaction. In lower locations total prevalence of Borrelia burgdorferi s.l. in Ixodes ricinus ticks was 35%. Single infection of Borrelia afzelii, B. garinii and B. burgdorferi sensu stricto (s.s.) was found in 59, 50 and 63 ticks, respectively (i.e. in 12.8, 11.2 and 14.1%). Double infection was found in 42 ticks (6.0%) and triple infection in three ticks (0.4%). The high frequency of B. burgdorferi s.s. exceeds the as yet reported occurrence in Central Europe. These circumstances are discussed. In mountain locations B. afzelii was found in five ticks, that including two co-infection with B. garinii, in elevations of 762 m and 1024 m above sea level, respectively. This fact signals a real danger of human infections in a region that was previously deemed to be without risk. Moreover, this region is more and more the target destination of tourist activities. The results also suggest that the penetration of infection can be rapid and formation and establishment of natural focus of Lyme borreliosis might be rather quick.     

Humans infected with relapsing fever spirochete Borrelia miyamotoi, Russia

Borrelia miyamotoi is distantly related to B. burgdorferi and transmitted by the same hard-body tick species. We report 46 cases of B. miyamotoi infection in humans and compare the frequency and clinical manifestations of this infection with those caused by B. garinii and B. burgdorferi infection. All 46 patients lived in Russia and had influenza-like illness with fever as high as 39.5°C; relapsing febrile illness occurred in 5 (11%) and erythema migrans in 4 (9%). In Russia, the rate of B. miyamotoi infection in Ixodes persulcatus ticks was 1%-16%, similar to rates in I. ricinus ticks in western Europe and I. scapularis ticks in the United States. B. miyamotoi infection may cause relapsing fever and Lyme disease-like symptoms throughout the Holarctic region of the world because of the widespread prevalence of this pathogen in its ixodid tick vectors.     

Synchronous phenology of juvenile Ixodes scapularis,vertebrate host relationships,and associated patterns of Borrelia burgdorferi ribotypes in the midwestern United States

To elucidate features of enzootic maintenance of the Lyme disease bacterium that affect human risk of infection, we conducted a longitudinal study of the phenology of the vector tick, Ixodes scapularis, at a newly invaded site in the north-central United States. Surveys for questing ticks and ticks parasitizing white-footed mice and eastern chipmunks revealed that I. scapularis nymphal and larval activity peaked synchronously in June and exhibited an atypical, unimodal seasonality. Adult seasonal activity was bimodal and distributed evenly in spring and fall. We discuss implications of these phenology data for the duration of the I. scapularis life cycle. Densities of Borrelia burgdorferi-infected, questing nymphs were comparable to those found in endemic areas elsewhere in the midwestern and northeastern U.S. Molecular genetic diversity of B. burgdorferi infecting these ticks and rodents was assessed by analysis of the ribosomal spacer types (RSTs). RST 1, a clade that includes strains with highly pathogenic properties, was relatively uncommon (3.4%) in contrast to the northeastern U.S., whereas less pathogenic ribotypes of the RST 2 and 3 clades were more common. These features of the ecology of this midwestern Lyme disease system likely contribute to the lower incidence of Lyme disease in humans in the Upper Midwest compared with that of the Northeast owing to reduced exposure to pathogenic strains of B. burgdorferi.     

Detection of four species of Borrelia burgdorferi sensu lato in Ixodes ricinus ticks collected from roe deer (Capreolus capreolus) in The Netherlands.

Roe deer (Capreolus capreolus) were investigated for their value as sentinel animals for Lyme borreliosis in the Netherlands. Serum was obtained from 114 roe deer, and 513 Ixodes ricinus, predominantly females (72%), were obtained from 47 animals (41%). The polymerase chain reaction was used to detect DNA of Borrelia burgdorferi sensu lato in a total of 190 ticks, comprising 106 engorged ticks and 84 non-engorged ticks. Borrelia DNA was detected in 24 engorged ticks (23%) and 26 non-engorged ticks (31%). This difference was not significant (P = 0.25). Four species of B. burgdorferi sensu lato were identified in the ticks. B. burgdorferi sensu stricto, Borrelia garinii, Borrelia afzelii and group VS116. B. afzelii was most commonly found and present in 13 mixed infections, and in 28 single infections. Fifteen sera (13%) contained antibodies to Borrelia spp. Ticks are more appropriate sentinel animals for Lyme borreliosis than roe deer, an important host for I. ricinus. Although the viability of borrelia spirochaetes in engorged ticks collected from roe deer was not assessed, a bloodmeal taken from roe deer did not eliminate borrelia spirochaetes from the tick. The relevance of this finding for transovarial transmission of borrelia spirochaetes in ticks is discussed.     

Borrelia species in Ixodes affinis and Ixodes scapularis ticks collected from the coastal plain of North Carolina

Ixodes affinis and I. scapularis are tick species that are widely distributed in the coastal plain region of North Carolina. Both tick species are considered enzootic vectors for spirochetal bacteria of the genus Borrelia and specifically for B. burgdorferi s.s., the pathogen most often attributed as the cause of Lyme disease in the USA. Laboratory testing of individual I. affinis and I. scapularis ticks for the presence of Borrelia DNA was accomplished by PCR, targeting 2 regions of the 16S-23S intergenic spacer. In I. affinis, Borrelia DNA was detected in 63.2% of 155 individual ticks. B. burgdorferi s.s. and B. bissettii were identified by DNA sequencing in 33.5% and 27.9% I. affinis, respectively. Statistical differences were found for sex distribution of Borrelia DNA between I. affinis females (76.8%) and I. affinis males (55.6%) where B. burgdorferi s.s. was more prevalent in females (44.6%) than in males (27.3%). In I. scapularis, 298 individually tested ticks yielded no Borrelia PCR-positive results. This study found a higher incidence of Borrelia spp. in I. affinis collected in coastal North Carolina as compared to previous reports for this tick species in other Southern states, highlighting the potential importance of I. affinis in the maintenance of the enzootic transmission cycle of B. burgdorferi s.l. in North Carolina. The lack of Borrelia DNA in I. scapularis highlights the need for additional studies to better define the transmission cycle for B. burgdorferi s.s. in the southeastern USA and specifically in the state of North Carolina.     

中国六省蜱中莱姆病螺旋体分离与鉴定

目的 了解中国6省蜱中莱姆病螺旋体携带情况.方法 在6省各选取2个采样点捕蜱,采用病原分离培养和巢式PCR方法对蜱进行莱姆病螺旋体检测,通过基因测序确定分型.结果 6省共采集到2200余只蜱,约1000只蜱用于病原分离培养,从吉林省长白县全沟硬蜱标本中分离到13株螺旋体,从贵州省道真粒形硬蜱标本中分离到9株螺旋体.1255只蜱用于PCR检测,从6省的蜱标本中检测到莱姆病螺旋体特异片段,其中吉林省(长白县27.08%、通化县20.41%)、青海省(互助县25.06%、黄南县21.11%)和贵州省(道真县25.63%)蜱中莱姆病螺旋体阳性率较高,山西省(垣曲县4.72%、交城县3.64%)蜱中莱姆病螺旋体阳性率较低.通过序列同源性分析确定吉林、青海、甘肃和山西省蜱中莱姆病螺旋体基因型均为Borrelia garinii.贵州、湖南省的基因型均为Borrelia valaisiana.结论 6省蜱中均带有莱姆病螺旋体,且带菌率有差异;山西省蜱中存在Borrelia ganmi型莱姆病螺旋体,湖南省蜱中存在Borrelia valaisiana型莱姆病螺旋体.     

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。     

Enzootic origins for clinical manifestations of Lyme borreliosis

Both early localized and late disseminated forms of Lyme borreliosis are caused by Borrelia burgdorferi senso lato. Differentiating between the spirochetes that only cause localized skin infection from those that cause disseminated infection, and tracing the group of medically-important spirochetes to a specific vertebrate host species, are two critical issues in disease risk assessment and management. Borrelia burgdorferi senso lato isolates from Lyme borreliosis cases with distinct clinical manifestations (erythema migrans, neuroborreliosis, acrodermatitis chronica atrophicans, and Lyme arthritis) and isolates from Ixodes ricinus ticks feeding on rodents, birds and hedgehogs were typed to the genospecies level by sequencing part of the intergenic spacer region. In-depth molecular typing was performed by sequencing eight additional loci with different characteristics (plasmid-bound, regulatory, and housekeeping genes). The most abundant genospecies and genotypes in the clinical isolates were identified by using odds ratio as a measure of dominance. Borrelia afzelii was the most common genospecies in acrodermatitis patients and engorged ticks from rodents. Borrelia burgdorferi senso stricto was widespread in erythema migrans patients. Borrelia bavariensis was widespread in neuroborreliosis patients and in ticks from hedgehogs, but rare in erythema migrans patients. Borrelia garinii was the dominant genospecies in ticks feeding on birds. Spirochetes in ticks feeding on hedgehogs were overrepresented in genotypes of the plasmid gene ospC from spirochetes in erythema migrans patients. Spirochetes in ticks feeding on hedgehogs were overrepresented in genotypes of ospA from spirochetes in acrodermatitis patients. Spirochetes from ticks feeding on birds were overrepresented in genotypes of the plasmid and regulatory genes dbpA, rpoN and rpoS from spirochetes in neuroborreliosis patients. Overall, the analyses of our datasets support the existence of at least three transmission pathways from an enzootic cycle to a clinical manifestation of Lyme borreliosis. Based on the observations with these nine loci, it seems to be justified to consider the population structure of B. burgdorferi senso lato as being predominantly clonal.     

Epidemiological and aetiological evidence for transmission of Lyme disease by adult Ixodes persulcatus in an endemic area in China

Involvement of adult Ixodes persulcatus ticks in the transmission of Lyme disease in Hailin County, Heilongjiang Province, China, is reported. In 1986 from April through August adult I. persulcatus was the dominant tick in this endemic area with an infection rate of 43% for the Lyme disease spirochaete, Borrelia burgdorferi. The incidence of Lyme disease cases presenting the symptom of erythema chronicum migrans (ECM) within this area was correlated with the seasonal abundance of adult I. persulcatus and the number of people bitten by ticks. The frequency of ECM formation in all age groups varied and was associated with the frequency of tick bites. In addition, a strain of B. burgdorferi was isolated from a pool of six female I. persulcatus collected from this area. We demonstrate that the seasonal abundance of adult I. persulcatus and its frequent attachment to humans result in the spring and summer transmission of Lyme disease in this endemic area. The role of immature I. persulcatus in Lyme disease transmission is apparently minimal.     

用聚合酶链方法对北京林区莱姆病疫源地及莱姆病病原体基因型的探索性研究

目的：进一步明确北京林区是否存在莱姆病的自然疫源地及其分布，方法基于莱姆病螺旋体外膜蛋白A基因建立半巢式聚合酶链式反应(polymerase chain reactio,PCR)方法，对从北京6个林区采集的蜱和鼠进行检测和基因分型，选择阳性标准本进行克隆和序列测定，与已知序进行同源性比较，间接免疫荧光法检测抗莱姆病螺旋体IgG抗体，从长角血蜱中分离莱姆病螺旋体。结果：从门头沟区东灵山采集的标本中检测到莱姆病螺旋体DNA片段，3只游离全沟硬蜱1只检测阳性，57只寄全沟硬蜱若蜱中1只检测阳性；119只野鼠中9只检测阳性，其中8只，B.garinii阳性，1只B.afzelii阳性。50份野鼠血清有5份莱姆病螺旋体IgG抗体阳性，采集采的160只长角血蜱（20只／组）。未分离到莱姆病螺旋体菌株。结论：北京门头沟区东灵山可能存在莱姆病的自然疫源地，包括两个基因型，全沟硬蜱可能是莱姆病的传播媒体，野鼠可能是贮存宿主。     

陕西省莱姆病自然疫源地调查研究

目的调查了解陕西省莱姆病自然疫源地。方法人群莱姆病螺旋体血清抗体检查,采用间接免疫荧光法(IFA);莱姆病患者,采用个案调查;蜱样,采用拖旗法采集;莱姆病螺旋体检测,采用巢式PCR法;莱姆病螺旋体基因分型,采用RFLP法。结果通过血清流行病学调查,陕西省富县张家湾镇、南郑县碑坝、陇县八渡镇3个农林地区人群莱姆病螺旋体自然感染率分别为8.33%(6/113)、8.88%(3/36)和7.51%(4/45)(P0.05),发现莱姆病患者14例,蜱类以嗜群血蜱和达吉克斯坦革蜱为优势种,检测蜱样1 116只。检测出阳性138只,总阳性率为12.35%。物种的阳性率分别为嗜群血蜱30.06%(107/356),达吉克斯坦革蜱3.88%(29/747),日本血蜱15.38%(2/13);检测出阳性蜱样138只,其中嗜群血蜱107只,84只为伽氏疏螺旋体基因型,23只为阿弗西尼疏螺旋体基因型;达吉克斯坦革蜱29只,24只为伽氏疏螺旋体基因型,5只为阿弗西尼疏螺旋体基因型;日本血蜱2只,均为伽氏疏螺旋体基因型。结论研究提示陕西省富县张家湾镇、南郑县碑坝、陇县八渡镇3个农林地区存在莱姆病自然疫源地。     

Use of mammalian museum specimens to test hypotheses about the geographic expansion of Lyme disease in the southeastern United States

Lyme disease, caused primarily in North America by the bacterium Borrelia burgdorferi sensu stricto, is the most frequently reported vector-borne disease in North America and its geographic extent is increasing in all directions from foci in the northeastern and north central United States. Several southeastern states, including Virginia and North Carolina, have experienced large increases in Lyme disease incidence in the past two decades, with the biggest changes in incidence occurring in the western portion of each state. We tested the hypothesis that B. burgdorferi s.s. was present in western Virginia and North Carolina Peromyscus leucopus populations prior to the recent emergence of Lyme disease. Specifically, we examined archived P. leucopus museum specimens, sampled between 1900 and 2000, for B. burgdorferi s.s. DNA. After confirming viability of DNA extracted from ear punch biopsies from P. leucopus study skins collected between 1945 and 2000 in 19 Virginia counties and 17 North Carolina counties, we used qPCR of two species-specific loci to test for the presence of B. burgdorferi s.s. DNA. Ten mice, all collected from the Eastern Shore of Virginia in 1989, tested positive for presence of B. burgdorferi; all of the remaining 344 specimens were B. burgdorferi-negative. Our results suggest that B. burgdorferi s.s was not common in western Virginia or North Carolina prior to the emergence of Lyme disease cases in the past two decades. Rather, the emergence of Lyme disease in this region has likely been driven by the relatively recent expansion of B. burgdorferi s.s. in southward-moving ticks and reservoir hosts in the mountainous counties of these two states.     

Risk of Lyme disease: perceptions of residents of a Lone Star tick-infested community.

BACKGROUND: Lone Star ticks (Amblyomma americanum) have been suggested as a vector of the agent of Lyme disease (Borrelia burgdorferi sensu lato) in the USA, based on associations with an infection manifesting mainly as erythema migrans. In laboratory experiments, however, they failed to transmit B. burgdorferi sensu stricto. METHODS: In this study, carried out from 1994 to 1996, we determined the seroprevalences of B. burgdorferi (1.2%), Ehrlichia chaffeensis (7%), E. phagocytophila (0%), Rickettsia rickettsii (0%), R. typhi (0%), Coxiella burneti (0%), Francisella tularensis (0%), and Babesia microti (0%) by standard serological methods for 325 residents (97% of the total population) of Gibson Island, coastal Maryland, USA, where 15% of the residents reported having had Lyme disease within a recent 5-year span. FINDINGS: Of the 167 seronegative individuals who were followed up prospectively for 235 person-years of observation, only 2 (0.85%) seroconverted for B. burgdorferi. Of 1556 ticks submitted from residents, 95% were identified as Lone Star ticks; only 3% were deer ticks (Ixodes dammini), the main American vector of Lyme disease. B. burgdorferi s.s. infected 20% of host-seeking immature deer ticks, and borreliae ("B. lonestari") were detected in 1-2% of Lone Star ticks. Erythema migrans was noted in 65% of self-reports of Lyme disease, but many such reports indicated that the rash was present while the tick was still attached, suggesting a reaction to the bite itself rather than true Lyme disease. Sera from individuals reporting Lyme disease generally failed to react to B. burgdorferi or any other pathogen antigens. CONCLUSION: The residents of Gibson Island had an exaggerated perception of the risk of Lyme disease because they were intensely infested with an aggressively human-biting and irritating nonvector tick. In addition, a Lyme disease mimic of undescribed etiology (named Masters' disease) seems to be associated with Lone Star ticks, and may confound Lyme disease surveillance. The epidemiological and entomological approach used in this study might fruitfully be applied wherever newly emergent tickborne zoonoses have been discovered.     

Borrelia in ticks biting humans and prevention of Lyme borreliosis

We examined by dark field microscopy 195 of 209 Ixodes ricinus ticks that were removed from humans in the Czech Republic (mainly in southern Moravia) during 1997-2001. The majority of the ticks were nymphs (62%), 31% were females and 7% larvae; 10.7% of the nymphs, 20.3% of the females but no larvae were found to be infected with B. burgdorferi s.l., the agent of Lyme borreliosis (LB). This observation supports for Central Europe the conclusions drawn from North America about nymphal ixodid ticks as the most important vector stage in transmission of LB. In the course of the year, we found the highest proportion of infected nymphal and female ticks taken off humans in June. The detection of borreliae in a human-biting tick is an important step that enables the general practitioner to prescribe prophylactic antimicrobial treatment and to reduce significantly the risk of Lyme disease in the patient.     

Small risk of developing Lyme borreliosis following a tick bite on Ameland: research in a general practice

OBJECTIVE: To investigate the percentage of ticks infected with Borrelia burgdorferi on the Dutch North Sea island of Ameland, and the risk of developing Lyme disease following tick bite on the island. DESIGN: Prospective, observational. METHOD: Ticks were collected from patients who visited a general practitioner and were tested for the DNA of B. burgdorferi. After 6 months the patients were interviewed by phone using a standardised questionnaire. RESULTS: From 2004-2006, 216 ticks were collected from 167 persons. Most ticks were removed within 24 hours. In 44 ticks (20.4%) B. burgdorferi DNA was detected. Follow up information was available on 146 persons, 41 (28.1%) of whom had been bitten by a Borrelia-positive tick. None of the persons developed a typical erythema migrans. From the 13 persons (9%) reporting a non-specific redness of the skin (diameter less than 5 cm) at the site of the tick bite, 5 had been bitten by a positive tick and 8 by a negative tick. One patient bitten by a positive tick reported systemic symptoms related to Lyme borreliosis, namely fatigue, perspiration and joint ache, without local redness. CONCLUSION: The probability of developing Lyme borreliosis was low even though a relatively large percentage of the ticks collected were positive for B. burgdorferi. This is probably connected to the fact that in the majority of cases the tick had been removed within 24 hours.     

Vector interactions and molecular adaptations of lyme disease and relapsing fever spirochetes associated with transmission by ticks

Pathogenic spirochetes in the genus Borrelia are transmitted primarily by two families of ticks. The Lyme disease spirochete, Borrelia burgdorferi, is transmitted by the slow-feeding ixodid tick Ixodes scapularis, whereas the relapsing fever spirochete, B. hermsii, is transmitted by Ornithodoros hermsi, a fast-feeding argasid tick. Lyme disease spirochetes are generally restricted to the midgut in unfed I. scapularis. When nymphal ticks feed, the bacteria pass through the hemocoel to the salivary glands and are transmitted to a new host in the saliva after 2 days. Relapsing fever spirochetes infect the midgut in unfed O. hermsi but persist in other sites including the salivary glands. Thus, relapsing fever spirochetes are efficiently transmitted in saliva by these fast-feeding ticks within minutes of their attachment to a mammalian host. We describe how B. burgdorferi and B. hermsii change their outer surface during their alternating infections in ticks and mammals, which in turn suggests biological functions for a few surface-exposed lipoproteins.     

Borrelia lusitaniae and green lizards (Lacerta viridis), Karst Region, Slovakia

In Europe, spirochetes within the Borrelia burgdorferi sensu lato complex are transmitted by Ixodes ricinus ticks. Specific associations are described between reservoir hosts and individual genospecies. We focused on green lizard (Lacerta viridis) as a host for ticks and potential host for borreliae. In 2004 and 2005, a total of 146 green lizards infested by ticks were captured, and 469 I. ricinus ticks were removed. Borrelial infection was detected in 16.6% of ticks from lizards. Of 102 skin biopsy specimens collected from lizards, 18.6% tested positive. The most frequently detected genospecies was B. lusitaniae (77.9%-94.7%). More than 19% of questing I. ricinus collected in areas where lizards were sampled tested positive for borreliae. B. garinii was the dominant species, and B. lusitaniae represented 11.1%. The presence of B. lusitaniae in skin biopsy specimens and in ticks that had fed on green lizards implicates this species in the transmission cycle of B. lusitaniae.     

从桂黔交界地区中华硬蜱中分离到莱姆病螺旋体

目的从桂黔交界地区捕获的蜱中分离莱姆病螺旋体,以探查广西壮族自治区（广西区）和贵州省莱姆病的传播媒介。方法用BSK-Ⅱ培养基从蜱中分离莱姆病螺旋体。用PCR扩增分离菌株的5S～23SrRNA基因间隔区,将PCR扩增产物克隆后测序,通过将测序结果与基因库中莱姆病螺旋体菌株的5S～23SrRNA基因间隔区进行同源性比较和分析,从而鉴定分离株的基因型。结果从捕获的中华硬蜱中分离出1株莱姆病螺旋体（命名为QLT1）。分离株经鉴定为Borrelia valaisiana基因型莱姆病螺旋体。结论中华硬蜱很有可能是广西区和贵州省莱姆病的传播媒介。     

吉林省长白及通化县莱姆病流行病学调查

目的了解吉林省长白及通化县林区人群、生物媒介蜱和宿主动物鼠的莱姆病螺旋体感染情况。方法在长白及通化县林区采集人群血清,并随机选择采样点进行捕蜱、捕鼠。采用间接免疫荧光法（IFA）检测血清,巢式PCR对蜱、鼠标本进行病原学检测,并通过基因测序方法确定基因型。同时蜱、鼠标本接种BSK培养基进行病原分离培养。结果从长白及通化县检查到人群血清莱姆病抗体IgG阳性率,长白县为12.04%（36/299）,通化县为9.35%（23/246）;蜱的带菌率,长白县为27.08%（39/144）,通化县为20.41%（20/98）;鼠的带菌率,长白及通化县均为10.00%（4/40,1/10）。通过序列同源性分析确定蜱和鼠携带的莱姆病螺旋体基因型存在Borrelia garinii。结论从血清学上证实长白及通化林区人群存在莱姆病螺旋体的感染,从病原学上证实全沟硬蜱和黑线姬鼠是当地莱姆病螺旋体的重要传播媒介和宿主。