我国莱姆病螺旋体生物媒介的初步调查

自1987年以来,我们在全国开展了莱姆病调查,从黑龙江、吉林、辽宁、内蒙、河北、新疆、湖北、四川、福建和北京等省、市采集的全沟硬蜱、粒形硬蜱、壤塘硬蜱、嗜群血蜱、二棘血蜱和长角血蜱分离出71株莱姆病螺旋体,其中55株从全沟硬蜱分离。全沟硬蜱是东北和西北针阔叶林区的优势蜱种,其带菌率为20~45%,表明全沟硬蜱是我国北方莱姆病螺旋体的主要生物媒介。虽然从我国南方的某些硬蜱属和血蜱属种类分离到莱姆病螺旋体,但是南方的主要生物媒介还不清楚。从我国蜱体内分离的螺旋体在超微结构、单克隆抗体反应和外表蛋白等方面与美国菌株有某些区别。     

Landscape ecology of Lyme disease in a residential area of Westchester County, New York

The landscape ecology of Lyme disease was studied in 1989 on 67 residences in an endemic area of Armonk, Westchester County, a northern suburb of New York City. Four main habitat types were defined, and each property was surveyed for immature and adult lxodes dammini ticks; 98.6% of 1,790 ticks collected were I. dammini. Overall, 67.3% were collected from woods, 21.6% from ecotone (unmaintained edge), 9.1% from ornamental vegetation, and 2% from lawns. Larval ticks were concentrated in woods, but nymphs and adults were widely dispersed in all habitats. Tick abundance was positively correlated with property size. Larger properties (greater than or equal to 0.5 acre) were more likely to have woodlots and, hence, more ticks. Dark-field and direct fluorescent microscopic examination of tick midgut tissues revealed that 29.6% of nymphs and 49.7% of adults were infected with Borrelia burgdorferi. Infected nymphs and adults were found on 36% and 60% of properties, respectively. These data indicate that the abundance of ticks capable of transmitting Lyme disease spirochetes is related to landscape features of the suburban residential environment.     

全沟硬蜱是我国北方地区莱姆病螺旋体的主要传播媒介

研究我国北方地区莱姆病螺旋体的生物媒介—蜱的种类、带菌状况及在传播莱姆病中的作用。用布旗法和动物诱捕法在山林地区采集蜱，分类鉴定，直接荧光抗体染色法查蜱中肠带菌率，ＢＳＫ培养基分离病原体，单克隆抗体鉴定菌株。调查蜱叮咬率与人群莱姆病感染率、患病率以及蜱的季节消长与莱姆病慢性游走性红斑（ＥＣＭ）病例发生的季节性关系。在北方１０省（市、区）共采集到１００００多只蜱，分属为２科７属１１种，以全沟硬蜱为优势种，占８０％～９５％。４种蜱的中肠携带莱姆病螺旋体，全沟硬蜱的带菌率高达２０．００％～４５．００％。从４种蜱分离到９８株莱姆病螺旋体，其中９０％以上是从全沟硬蜱分离的。全沟硬蜱叮咬率高的人群，莱姆病的感染率和患病率也高。全沟硬蜱的季节消长与ＥＣＭ发生的季节性相一致。证实我国北方地区至少有４种蜱的中肠内携带莱姆病螺旋体，莱姆病螺旋体的主要生物媒介是全沟硬蜱。     

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.     

Temporal relation between Ixodes scapularis abundance and risk for Lyme disease associated with erythema migrans

Understanding the role that nymphal and female ticks, Ixodes scapularis, have in the epidemiology of Lyme disease is essential to the development of successful prevention programs. In this study, the authors sought to evaluate the seasonal and annual relations between tick densities and patients > or = 16 years of age diagnosed with erythema migrans (EM), the rash associated with early Lyme disease. Ticks were collected weekly by drag sampling throughout most of the year from 1991 to 1996 in Westchester County, New York. The number of EM cases was based on patients diagnosed at the Westchester County Medical Center using Centers for Disease Control and Prevention (CDC) criteria. No patients with EM were diagnosed from January through April, when only adult ticks were active. Correlation analysis between monthly tick densities and EM incidence was significant for nymphs (r = 0.87, p < 0.01), but not for adult ticks (r = -0.57, p > 0.05). There was a strong, although not significant, correlation between peak annual number of patients with EM and peak nymphal tick abundance (r = 0.76, p = 0.08). These data indicate that bites from adult I. scapularis only rarely result in Lyme disease, and that annual nymphal tick abundance determines exposure. This suggests that annual fluctuations in Lyme disease case numbers are largely due to natural changes in tick abundance and, therefore, that control of nymphal I. scapularis should be a major component of Lyme disease prevention efforts.     

Lyme disease: a proposed ecological index to assess areas of risk in the northeastern United States

BACKGROUND: Recent public awareness has resulted in a demand for information about ways to reduce the risk of acquiring Lyme disease. METHODS: Twenty-two school properties and recreational areas within a Lyme disease endemic area of central Monmouth County, New Jersey were evaluated for risk of transmission using an ecological index on the suitability, amount, and access to Ixodes dammini habitat by target human populations and the abundance of infected adult ticks. RESULTS: The characterization of tick habitat accurately predicted the elimination of 11 sites from concern. Of the remaining 11 sites, six were classified high risk and five as moderate risk. On-site tick surveys identified infected I. dammini adults at only four sites (three risk; one moderate risk). CONCLUSIONS: These results indicate that the use of selected ecological parameters provides a cost-effective method to rapidly identify areas at risk for Lyme disease transmission.     

我国东北林区莱姆病的调查

1987~1988年我们在牡丹江和延边林区对莱姆病进行了流行病学调查和临床观察,发现一些林场莱姆病的患病率和自然感染率较高。大青林场共有人口1 030人,在检查的628人中,发现莱姆病患者37例。在小白林场人群中进行了血清流行病学调查,发现伯氏包柔氏体自然感染率为22.5%。从牡丹江林区收集的全沟硬蜱中,分离出了3株包柔氏体,其中M7菌株经单克隆抗体测定和电镜观察,确证为伯氏包柔氏体。在医院收集162份疑似森林脑炎病人血清,其中38份血清抗伯氏包柔氏体抗体阳性。对15例经临床和血清学确诊的莱姆病患者进行了临床观察和治疗,证明大剂量青霉素可以治愈全身性红斑。并从1例慢性游走性红斑患者血液中分离出1株包柔氏体。     

Lyme disease: prophylaxis after tick bite

Lyme disease is a bacterial infection caused by Borrelia burgdorferi, which is transmitted by infected ticks. The transmission depends on several factors, especially on the duration of the tick's presence in the host body (the nymph which is smaller than the adults and thus less visible, is in this case the most frequently involved) and on whether the tick is infected or not. The interpretation of results in the few available studies is made difficult by the lack of information obtained (due to difficulty to collect information and examination costs). The comparison is made even more difficult by the difference between Borrelia ticks species in various regions. Today, the best methods are preventive: protective clothing, tick repellents, checking and removal of ticks after a journey in an endemic zone, and in case of tick bite, regular examination of the bite site during the following weeks in order to initiate an early curative treatment if ECM is diagnosed. The currently available data seems to be insufficient to suggest systematic antimicrobial prophylaxis in case of tick bite.     

承德地区莱姆病自然疫源性特征分析

目的了解承德地区莱姆病自然疫源地存在状况。方法于承德林区捕鼠、采蜱；巴伯-斯托纳-凯利培养基(BSK)分离蜱内病原体；PCR扩增蜱、鼠体内目的片段及序列测定；对林区居民及动物牛、羊进行血清抗体检测。结果全沟硬蜱为优势蜱种，从中PCR扩增出目的片段，基因序列同源性比较，提示此感染菌株与欧亚大陆常见的莱姆病螺旋体Borrelia afzelii种具有高度同源性。林区居民及动物牛、羊血清抗体检出阳性率较高，分别为13．3％，23．3％，30％。结论全沟硬蜱是承德地区的优势蜱种；并发现其感染有致病性莱姆病螺旋体Borrelia afzelii种。林区羊、牛为重要的贮存宿主。林区人群存在莱姆病螺旋体自然感染，可初步认定承德地区为莱姆病自然疫源地。     

Diversity of tick species biting humans in an emerging area for Lyme disease.

BACKGROUND. Although most tick bites in humans in areas of the northeastern United States in which Lyme disease is highly endemic are due to Ixodes dammini, no study documents the frequency of I. dammini bites in low-prevalence or emerging areas for Lyme disease. Data on the proportion of tick bites in humans that are due to I. dammini in a region may have implications for public health policy and clinical management. METHODS. A statewide survey of the tick species that parasitized humans in Maine was conducted during 1989 and 1990. Tick submissions from throughout the state were elicited through media announcements. All ticks that had been removed from humans were identified, and data were collected that included bite seasonality and geography and demographics of tick bite victims. RESULTS. Of 709 ticks submitted, only 17% were I. dammini. Ixodes cookei, a vector for Powassan encephalitis, accounted for 34% of bites, and Dermacentor variabilis accounted for 45%. Other tick species were occasionally implicated. CONCLUSIONS. The likelihood that a tick bite was due to I. dammini was lower in Maine than in areas in the northeastern United States in which Lyme disease is highly endemic. Other tick vectors, associated with diseases other than Lyme disease, were more frequently implicated. Regional tick bite surveys may prove useful in assessing the risk of Lyme disease following a tick bite.     

吉林省重要媒介蜱与莱姆病关系的研究

目的探讨重要媒介蜱类与莱姆病的关系。方法根据多年收集的蜱类标本鉴定,结合血清流行病学调查结果,探讨两者关系。结果吉林省有蜱类2科5属15种。结论全沟硬蜱是吉林省莱姆病的主要媒介。     

Potential for exposure to tick bites in recreational parks in a Lyme disease endemic area.

Eight recreational parks located in a Lyme disease endemic area of southern New York State were surveyed for the presence of ticks during the summer of 1985 by drag sampling. Ixodes dammini, the primary vector of Lyme disease in the northeast, was found in all but one park and accounted for 580 (91.8 per cent) of the 632 ticks collected. Of these, 18 per cent were larvae, 80 per cent were nymphs, and 2 per cent were adults. An I. dammini encounter distance, defined as the mean number of meters traveled before encountering a nymphal or adult I. dammini on a drag cloth, ranged from 36 m in high-risk parks, to infinity (no tick encounters). Generally, areas of high use presented higher encounter distances (lower risk) than those of the entire park. Two of the three parks with the highest annual attendance also had the highest I. dammini population indices as projected from our sampling regimen. These results indicate that recreational parks in Lyme disease endemic areas represent a substantial human risk for tick bites and Lyme disease.     

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。     

二棘血蜱生态习性及其特点的初步研究

目的：初步研究莱姆病主要媒介二棘血蜱的生态习性及其特征。方法：采用流行病学调查方法在疫源地进行相关因素的研究,分析其相关特点。结果：二棘血蜱为当地优势蜱种,其密度为275只/布旗人工小时;该蜱中肠检查带菌率为40%;从50只二棘血蜱分离到8株莱姆病螺旋体;该蜱有明显的季节消长和时限性;6-7月是二棘血蜱的繁殖期,其数量与气温、雨量密切相关;蜱的数量变化与生境等因素有关。其特征：二棘血蜱在疫源地内呈岛状分布;密度与农作物接壤的林间或林边草坪高于其他生境;二棘血蜱的数量变化与人畜野外活动频繁环境相关;该蜱喜向阳、光线充足、较湿润、浅草坪的生镜。结论：通过流行病学调查,初步掌握了二棘血蜱的生物学特征,为进一步研究莱姆病提供了依据。     

Prevalence of Ixodes dammini near the homes of Lyme disease patients in Westchester County, New York

Cases of Lyme disease that occurred in Westchester County, an affluent suburb north of New York City, in 1983 were investigated in 1983 and 1984 to determine the presence of Ixodes dammini (Acari: Ixodidae) in the vicinity of the patients' homes. Small mammal trapping, drag cloth, and carbon dioxide-baited tick traps were used to sample ticks. In all but one of 11 cases investigated, I. dammini was found on or near well-maintained lawns in the immediate vicinity of the residences. A mark-release-recapture experiment to determine tick abundance in one 700 m2 lawn resulted in an estimate of 6800 adult ticks (approximately 1 per m2). Dark-field microscopic examination of tick midgut tissues revealed that 33% of nymphs and 55% of adult ticks from this lawn contained spirochetes. These data suggest that many cases of Lyme disease in Westchester County, New York, may be acquired at home as a result of activities on the lawn.     

大兴安岭南段莱姆病的调查

1991年4～6月,我们在大兴安岭南段林区,对莱姆病进行了调查,应用间接免疫荧光抗体法检测496人居民血清,38人血清中抗莱姆病螺旋体IgG抗体效价≥1:128。根据临床表现和血清学调查,确诊莱姆病病例22例;从26只全沟硬蜱分离出4株莱姆病螺旋体。     

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。     

伯氏疏螺旋体在全沟硬蜱体内的分布与经卵传递

本实验首次证实全沟硬蜱可经卵传递伯氏疏螺旋体,2只卵巢感染螺旋体的雌蜱的子代感染率分别为59%和29%。伯氏疏螺旋体主要分布于全沟硬蜱的中肠内,饥饿和饱血蜱的中肠感染率相近,分别为30.9%和29.0%:而两者的全身感染与中肠感染之比则分别为2.9%和15.0%。     

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.     

Hypersensitivity to ticks and Lyme disease risk

Although residents of Lyme disease-endemic regions describe frequent exposure to ticks, Lyme disease develops in relatively few. To determine whether people who experience cutaneous hypersensitivity against tick bite have fewer episodes of Lyme disease than those who do not, we examined several factors that might restrict the incidence of Lyme disease among residents of Block Island, Rhode Island. Of 1,498 study participants, 27% (95% confidence interval [CI] 23%-31%) reported > or = 1 tick bites, and 17% (95% CI 13%-21%) reported itch associated with tick bite in the previous year. Borrelia burgdorferi infected 23% (95% CI 20%-26%) of 135 nymphal Ixodes scapularis (I. dammini) ticks. The likelihood of Lyme disease infection decreased with >3 reports of tick-associated itch (odds ratio 0.14, 95% CI 0.94-0.03, p = 0.01). Prior exposure to uninfected vector ticks protects residents of disease-endemic sites from Lyme disease.