中国云南洱海周边小兽体表革螨多样性（英文）

云南大理洱海周边是我国流行性出血热的流行地区之一。本文目的是运用Shannon-Wiener、系统聚类分析方法（SPSS 13.0软件）和Levins'niche等对该区3 303只小兽体表寄生革螨的物种多样性、群落结构、相似性、分布和生态位进行研究。选择的洱海周边三个不同方位恰好处于东部无量山、南部哀老山和西部苍山,由于洱海的天然隔离使这三个方位形成了同地域异生境的地理景观。在调查点共捕获小兽宿主3 303只属4目（啮齿目、食虫目、攀鼩目和食肉目）7科15属21种,收集到的小兽体表寄生虫革螨23 196只被鉴定为6科16属43种。研究结果表明革螨群落结构复杂,物种多样性高。在不同方位革螨和它们相对应宿主的分布是不均匀的,但是洱海周边不同方位同样优势小兽上寄生的优势革螨种是一致的。结果暗示：生境影响着革螨和它们相对应小兽的物种构成和分布,如果小兽宿主的分类地位和生境相似,那么相对应的小兽宿主上的革螨群落就相似; 不同方位小兽体表寄生虫革螨的丰富度和物种多样性主要由宿主本身和宿主所栖息的生境决定;这可能是小兽和革螨之间协同进化在生态学上的一个佐证。但通过使用革螨的生态位宽度分析,革螨的宿主特异性很低,这又可能暗示着小兽和革螨之间有协同进化,但协同进化程度不高。     

中国云南洱海周边小兽体表吸虱多样性

在2003—2004年对云南大理洱海周边小兽体表寄生吸虱进行了调查,诱捕小兽3303只,隶属4目7科、15属、21种,共收集14635只吸虱,共计5科、6属、21种。调查点位于洱海周边3个不同方位,恰好处于无量山（洱海东部）、哀牢山（洱海南部）和苍山（洱海西部）3座山的连接地段,由于洱海的天然隔离使这3个方位形成了同地域（经度、纬度、海拔和动物地理区划相同）异生境的地理景观。此项研究的目的是调查同地域异生境里小兽体表吸虱在物种多样性、丰富度、群落结构、相似性和分布。结果表明吸虱的物种多样性低,群落结构简单。吸虱的丰富度、分布和物种多样性随着宿主和生境的不同而存在着显著的差异,这可能暗示着生态环境影响着吸虱和它相对应的小兽宿主的构成和分布。某种宿主经常有某种固定的吸虱,在动物分类上近缘关系较近的小兽宿主,其体表昆虫群落相似性较高。洱海周边不同方位同种小兽宿主上的吸虱物种相同,这个结果强烈暗示着吸虱与其对应宿主之间有明显的协同进化关系。     

中国云南小兽体表革螨的群落相似性

运用系统聚类分析方法对中国云南省境内17种主要小型哺乳动物(小兽)体表革螨群落相似性进行研究,每一种小兽体表的所有外寄生革螨被定义为一个相应的革螨群落。运用SPSS11.5软件完成17种革螨群落的相似性比较。研究结果表明:小兽体表革螨群落结构复杂,物种多样性高;隶属同一个属的小兽体表的革螨群落相似程度高,在系统聚类分析中聚为一类;大多数革螨群落相似性大小与相应小兽宿主在动物分类上的近缘性高低呈现高度一致,但也有一些革螨群落是例外的。这说明小兽体表革螨群落不仅受小兽宿主分类地位的影响,可能还受宿主生境的影响     

中国云南小兽寄生革螨的群落结构和空间分布

寄生在小兽体表的革螨可能是传播肾综合征出血热和立克次体痘等人兽共患病的媒介。本文报道了云南省28个县(市)小兽体表革螨的野外调查结果, 运用物种数、平均丰富度和Shannon多样性指数对小兽寄生革螨的群落特征和沿环境梯度的空间分布进行了研究, 并用系统聚类分析法 (SPSS 16.0软件)对18种主要小兽的革螨群落相似性进行了比较。在云南省28个县(市)共捕获到小兽14 544头, 隶属于5目（啮齿目、食虫目、攀鼩目、兔形目、食肉目）10科35属67种, 在捕获的小兽体表采集到革螨80 791头, 经鉴定属于10科33属112种。结果分析表明: 主要的宿主动物为黄胸鼠 Rattus tanezumi、齐氏姬鼠Apodemus chevrieri和大绒鼠Eothenomys miletus;纳氏厉螨Laelaps nuttalli、毒厉螨L. echidninus和贵州厉螨L. guizhouensis为革螨的优势种。齐氏姬鼠A. chevrieri、社鼠N. confucianus和黄胸鼠R. tanezumi体表寄生的革螨种类最多;臭鼩鼱Suncus murinus、齐氏姬鼠A. chevrieri和灰麝鼩Crocidura attenuata的革螨群落多样性最高。聚类分析结果表明, 大部分革螨群落的相似程度与相应小兽的亲缘关系及所处生态环境的相似性是基本一致的, 分类地位和生境选择相似的小兽, 它们的革螨群落也被聚为一类。革螨物种数沿纬度梯度的水平分布呈现两个峰值, 最大峰值出现在25°~26°N之间;沿海拔梯度的垂直分布呈单峰分布格局, 峰值在海拔2 000~2 500 m之间。革螨和小兽的多样性沿纬度梯度和海拔梯度的空间分布趋势也均表现出随着纬度和海拔的升高而先升高后降低的单峰型分布格局, 峰值分别出现在北纬25°~27°N和海拔2 000~2 500 m之间。结果提示云南革螨群落种类丰富, 多样性高。云南革螨物种数和多样性的分布格局可能直接受到古北和东洋两区系边缘效应的影响。     

山东部分地区小兽类寄生恙螨的群落结构

用鼠笼捕捉活鼠,收集体外恙螨,分类计数,定量分析小兽类体外寄生恙螨的群落结构。探讨山东小兽类体外寄生恙螨群落结构及其与疾病的关系。结果表明,当地5种小兽类体外共有6种寄生恙螨。黑线姬鼠、大仓鼠体外寄生螨种较丰富,各有5种寄生螨。小盾纤恙螨宿主范围广,在4种小兽的体外均有发现。大仓鼠体外太平洋无前恙螨的带螨率和带螨指数最高(72．73％、52．00),临淮岗纤恙螨、泰山纤恙螨、须纤恙螨普遍寄生于黑线姬鼠、大仓鼠体外。黑线姬鼠与大仓鼠寄生螨群落多样性指数相对较高。黑线姬鼠寄生螨群落与大仓鼠的相似系数最大(39．2)。黑线姬鼠体外恙螨群落结构随季节变化而发生变化,恙螨群落的丰富度和多样性指数以冬季(12～2月)最低,春、秋季较高。     

中国云南洱海周边大足鼠的体表寄生螨

用U检验和相关分析的统计方法对2003～2004年云南洱海(中国滇西北著名的淡水湖泊)周边251只大足鼠体表寄生螨进行了调查.调查点是我国11大鼠疫自然疫源地之一,也是我国恙虫病和出血热的流行地区.大足鼠已经被鉴定为鼠疫、汉坦病毒、恙虫病和流行性出血热的储存宿主.我们的研究发现大足鼠携带好几种与人兽共患病有关的螨类.为了丰富大足鼠体表寄生螨的研究,在此,对大足鼠的体表寄生螨群落和体表寄生螨医学和兽医学的重要性进行了描述.有191只大足鼠寄生有体表寄生螨,侵染率为76%.采集到的体表寄生螨有35种,包括15种恙螨和20种革螨.其中6种以前已经被证明是人类疾病的主要媒介.因此大足鼠很显然成为流行性出血热和恙虫病等病原体的贮存宿主.     

中国云南部分小兽体表吸虱昆虫群落相似性及群落分类研究(英文)

应用系统聚类分析方法对云南省境内24种主要小型哺乳动物(小兽)体表吸虱昆虫群落相似性及群落分类进行了研究。研究中将每一种小兽体表的所有吸虱昆虫定义为一个相应的吸虱群落单位。结果表明,小兽体表吸虱群落结构简单,物种多样性很低。多数小兽有固定的吸虱种类寄生,其吸虱的宿主特异性高。在动物分类上隶属同一个属的小兽,其体表吸虱群落相似程度高,在系统聚类分析中大多被归为一类。在动物分类上近缘的小兽,其体表吸虱群落相似,优势虱种相同或相似,此情形尤其表现在鼠属、白腹鼠属、姬鼠属和绒鼠属。吸虱群落相似性大小与相应小兽宿主在动物分类地位上的近缘性高低呈现高度一致。从生态学角度来看,吸虱昆虫与其所寄生的小兽宿主动物之间存在密切的协同进化关系。     

中国云南吸虱昆虫物种多样性及群落结构研究(英文)

在对云南省9个县(市)抽样调查的基础上,本文对境内小型哺乳动物(小兽)体表吸虱昆虫物种多样性及群落结构进行了研究。物种多样性用物种丰富度表示,多样性指数及均匀度计算采用Shannon-Wiener方法。所捕获的2745只小兽经分类鉴定隶属啮齿目、食虫目、攀目、兔形目和食肉目5个目中的10科、25属、41种。从各种小兽宿主体表共采集到吸虱昆虫18165只,经分类鉴定隶属4科、6属、22种,其种类明显少于宿主种类。几乎每种小兽宿主体表都有固定的吸虱种类寄生,但吸虱种类数很少(1-4种)。动物分类上接近的宿主,其体表的优势吸虱种类基本相同。研究结果表明,小型哺乳动物体表吸虱昆虫的物种多样性很低,群落结构十分简单。研究同时提示,吸虱昆虫与小兽宿主之间可能存在高度一致的协同进化关系。     

中国云南洱海周边褐家鼠的体表寄生虫群落组成

褐家鼠Rattus norvegicus可能是云南省部分鼠疫流行区的储存宿主之一, 其体表的某些寄生虫种类可能是人类疾病的传播媒介。为了解洱海周边地带褐家鼠的体表寄生虫群落, 并对其医学和兽医学的重要性进行描述。用U检验和相关分析的统计方法对2003-2004年采自云南洱海（中国滇西北著名的淡水湖泊）周边地区的431头褐家鼠的体表寄生虫群落进行了研究。用构成比（C）, 侵染率(P)和平均丰富度(A)反映体表寄生虫的流行和密度状况。调查点位于我国11大鼠疫自然疫源地之一, 此地也是我国恙虫病和流行性出血热的流行地区。结果表明: 431头褐家鼠中307头寄生有体表寄生虫, 侵染率为71%。采集到的体表寄生虫有47种, 包括23种恙螨、16种革螨、6种蚤和2种吸虱, 其中16种以前已经被证明是人类疾病的媒介。结果提示褐家鼠的体表寄生虫物种多样性高。     

中国云南人间鼠疫流行区十种小兽体表蚤类群落的比较(英文)

本文将某一种小兽 (小型哺乳动物 )宿主体表的全部蚤作为一个特定的蚤类群落 ,在此基础上运用模糊聚类分析方法对云南人间鼠疫流行区 10种小兽体表的蚤类群落之间的相似性进行了比较。研究结果表明 ,在动物分类上比较接近的、隶属同一属 (鼠属 )的黄胸鼠、大足鼠和斯氏家鼠体表 3种蚤类群落之间的相似性较大 ,在模糊聚类的谱系图上明显聚为一类。动物分类上距离较远、隶属不同属的微尾、臭、灰麝、中华姬鼠、滇绒鼠、社鼠和锡金小鼠体表的 7种蚤类群落之间的相似性较小。结果提示 ,宿主因素可能是影响体表寄生蚤群落之间相似性大小的一个主要因子 ,当宿主在动物分类上彼此接近时 ,其体表寄生蚤群落的相似程度就比较高 ,当宿主在动物分类上距离较大时 ,其体表蚤类群落的相似程度就比较低。本文中不同属小兽体表寄生蚤类形成了不同的群落类型。     

Susceptibility to <Emphasis Type="Italic">Yersinia pestis</Emphasis> Experimental Infection in Wild <Emphasis Type="Italic">Rattus rattus</Emphasis>, Reservoir of Plague in Madagascar

In Madagascar, the black rat, Rattus rattus, is the main reservoir of plague (Yersinia pestis infection), a disease still responsible for hundreds of cases each year in this country. This study used experimental plague challenge to assess susceptibility in wild-caught rats to better understand how R. rattus can act as a plague reservoir. An important difference in plague resistance between rat populations from the plague focus (central highlands) and those from the plague-free zone (low altitude area) was confirmed to be a widespread phenomenon. In rats from the plague focus, we observed that sex influenced plague susceptibility, with males slightly more resistant than females. Other individual factors investigated (weight and habitat of sampling) did not affect plague resistance. When infected at high bacterial dose (more than 10⁵ bacteria injected), rats from the plague focus died mainly within 3–5 days and produced specific antibodies, whereas after low-dose infection (< 5,000 bacteria), delayed mortality was observed and surviving seronegative rats were not uncommon. These results concerning plague resistance level and the course of infection in the black rat would contribute to a better understanding of plague circulation in Madagascar.     

Flea diversity as an element for persistence of plague bacteria in an East African plague focus

Plague is a flea-borne rodent-associated zoonotic disease that is caused by Yersinia pestis and characterized by long quiescent periods punctuated by rapidly spreading epidemics and epizootics. How plague bacteria persist during inter-epizootic periods is poorly understood, yet is important for predicting when and where epizootics are likely to occur and for designing interventions aimed at local elimination of the pathogen. Existing hypotheses of how Y. pestis is maintained within plague foci typically center on host abundance or diversity, but little attention has been paid to the importance of flea diversity in enzootic maintenance. Our study compares host and flea abundance and diversity along an elevation gradient that spans from low elevation sites outside of a plague focus in the West Nile region of Uganda (~725-1160 m) to higher elevation sites within the focus (~1380-1630 m). Based on a year of sampling, we showed that host abundance and diversity, as well as total flea abundance on hosts was similar between sites inside compared with outside the plague focus. By contrast, flea diversity was significantly higher inside the focus than outside. Our study highlights the importance of considering flea diversity in models of Y. pestis persistence.     

Contrasted patterns of selection on MHC-linked microsatellites in natural populations of the Malagasy plague reservoir

Plague (Yersinia pestis infection) is a highly virulent rodent disease that persists in many natural ecosystems. The black rat (Rattus rattus) is the main host involved in the plague focus of the central highlands of Madagascar. Black rat populations from this area are highly resistant to plague, whereas those from areas in which the disease is absent (low altitude zones of Madagascar) are susceptible. Various lines of evidence suggest a role for the Major Histocompatibility Complex (MHC) in plague resistance. We therefore used the MHC region as a candidate for detecting signatures of plague-mediated selection in Malagasy black rats, by comparing population genetic structures for five MHC-linked microsatellites and neutral markers in two sampling designs. We first compared four pairs of populations, each pair including one population from the plague focus and one from the disease-free zone. Plague-mediated selection was expected to result in greater genetic differentiation between the two zones than expected under neutrality and this was observed for one MHC-class I-linked locus (D20Img2). For this marker as well as for four other MHC-linked loci, a geographic pattern of genetic structure was found at local scale within the plague focus. This pattern would be expected if plague selection pressures were spatially variable. Finally, another MHC-class I-linked locus (D20Rat21) showed evidences of balancing selection, but it seems more likely that this selection would be related to unknown pathogens more widely distributed in Madagascar than plague.     

Seasonal dynamics of infecting ability of the flea Citellophilus tesquorum altaicus in the Tuva natural focus of the plague

The infecting ability of the fleas Citellophilus tesquorum altaicus loff, 1936, the main plague vectors in the Tuva natural focus, was experimentally studied in different periods of the epizootic season. Seasonal dynamics in the efficiency of infecting the long-tailed Siberian souslik with the plague causative agent through flea bites was noticed. Seasonal differences in infectivity of the "blocked" flea bites are revealed. An increase of infected experimental animals with a generalization of infection process in the period of epizooty activation in the natural focus was observed. A resistance of the long-tailed Siberian souslik to the plague agent infection through flea bites in the spring season was registered.     

Draft Genome Sequence of Yersinia pestis Strain 2501, an Isolate from the Great Gerbil Plague Focus in Xinjiang, China

We deciphered the genome of Yersinia pestis strain 2501, isolated from the Junggar Basin, a newly discovered great gerbil plague focus in Xinjiang, China. The total length of assembly was 4,597,322 bp, and 4,265 coding sequences were predicted within the genome. It is the first Y. pestis genome from this plague focus.     

Broader investigation into the external environment of the specific antigen of the infectious agent in epizootiological observation and study of the structure of natural foci of plague.

The possibilities of detection of the infectious agent in natural foci of plague can be expanded to some extent by using the method of search for the specific FI capsular antigen of the plague microbe in such objects of the external environment which have not yet been subjected to laboratory analysis and serological analysis in particular. Such objects include soil from the burrow and the substrate of the nest of the rodent as well as the fleas of rodents and regurgitations of birds of prey.The effectivity and suitability of examination of these objects using immuno-adsorption reactions with standard erythrocyte diagnostics (passive haemagglutination reaction, antibody neutralization reaction) were demonstrated experimentally and confirmed under field conditions in various geographical and ecological zones of the Caucasus. Thus in 1971, an earlier unknown natural focus of plague was found in the Mount Elbrus massif by means of serological analysis of the substrate of the nest and of the soil from the burrows of rodents. It can be expected that broadened serological search for the FI antigen of plague will prove useful in the study of the structure of natural foci of plague, in the reconnaissance or retrospective investigation of poorly explored territories and in the solution of some questions concerning the epizootiology of plague, such as the survival of the infectious agent in the inter-epizootic period, telluric plague, etc.     

The epizootiological role of the population organization of the stock of fleas on the long-tailed suslik in a natural focus of plague in Tuva

Spatial location of epizootic events in the Tuva plague focus is determined at a considerable degree by the population structure of the flea Citellophilus tesquorum--the main plague microbe vector. Within the enzootic territory occupied by five populations of the long-tailed ground squirrel (Citellus undulatus) there are six populations of C. tesquorum. Each population of fleas has a corresponding autonomic plague focus. Various conditions for the microbe life activity in these populations are recovered. The circulation of the microbe is closely connected with certain intrapopulation groupings of fleas--the nuclei of populations.     

The ability of flea species on the common vole from mountainous Dagestan to transmit and preserve the causative agent of plague

The infection ability and terms of preservation of plague microbe in fleas of common vole from Dagestan high-mountain plague focus (Frontopsylla causasica, Megabothris turbidus, Ctenophthalmus intermedius and Amphipsylla rossica) was studied experimentally. Block formation and transmission of the infection by F. caucasica and M. turbidus was observed. The transmission of plague microbe by Ct. intermedius fleas was first carried out. These species of fleas preserve the infection for a long time. Experiments with fleas of A. rossica yielded negative results.     

Susceptibility to Yersinia pestis in the northern grasshopper mouse (Onychomys leucogaster)

The laboratory-born progeny from two geographically distant populations of northern grasshopper mice (Onychomys leucogaster) were challenged with Yersinia pestis to determine their relative susceptibilities to plague. One of the O. leucogaster populations was associated with a known epizootic focus of the disease and was found to be nearly 2,000 times more resistant to mortality than were members of another population from an area historically free of plague. The ecology and omnivorous behavior of O. leucogaster appears to promote strong selection for resistance to plague in areas where they are naturally exposed.     

Dispersal of the flea Ctenophyllus hirticrus and spreading of plague epizooties in Gorny Altai

Gradual dispersion of an abundant flea species Ctenophyllus hirticrus specific to the Pallas's pika (the main plague carrier), is revealed in the Gorno-Altai natural plague focus on the territory, occupied by two populations of this lagomorph. Spreading of Yersinia pestis in these areas took place a short time later the rise of this ectoparasite's abundance. It is supposed that the colonization of these areas by C. hirticrus was one of the factors determined epizooties spreading within the focus and formation of new sites of stable Y. pestis preservation.