Transmission of Ehrlichia chaffeensis by Adult Ticks

成年蜱传播查菲埃里希体

• 批准号: 6895239
• 负责人: ROGER William STICH
• 金额: $ 14.54万
• 依托单位: OHIO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-08-01 至 2005-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6895239
• 关键词: Ehrlichia; Ixodes; arthropod borne communicable disease; communicable disease transmission; disease vectors; dogs; ehrlichiosis; epidemiology; gender difference; host organism interaction; larva; mature animal; polymerase chain reaction; sex behavior; species difference; technology /technique development; ticks

DESCRIPTION (provided by the applicant): Approaches to the control of human monocytic ehrlichiosis (HME), the most prevalent zoonotic ehrlichial disease reported in the USA to date, rely on better understanding of interactions between Ehrlichia chaffeensis, the etiologic agent, and its tick host. It has been demonstrated that several ixodid genera, including Amblyomma, Dermacentor and Ixodes, can be naturally infected with E. chaffeensis. Although detection of E. chaffeensis in naturally exposed ticks indicates susceptibility of these ticks to infection, it does not demonstrate their ability to transmit this pathogen to a susceptible vertebrate host. Repeated experimental transmission of an arthropod-borne pathogen by the suspected vector(s) is chief among the criteria that must be fulfilled before the competent vector(s) is (are) incriminated. The objective of this particular application, which is an essential step in determining the mechanisms behind tick transmission of E. chaffeensis, is to identify tick species and pathogen-acquisition scenarios that lead to effective experimental transmission of this pathogen. The central hypothesis of this project is that intrastadially infected adult male ixodid ticks are more effective experimental vectors of E. chaffeensis than adult female or trans-stadially infected adult male ticks. This central hypothesis will be tested through fulfillment of specific aims focused on (1) development of a PCR assay for E. chaffeensis that is sensitive enough to detect the pathogen within individual experimentally infected ticks, (2) intrastadial and transstadial tick-transmission of E. chaffeensis and (3) transmission of E. chaffeensis to multiple hosts by adult male ticks. The rationale for the proposed research is that it will lead to better understanding of the potential importance of different tick species and acquisition scenarios in the transmission of E. chaffeensis under natural conditions. Furthermore, once effective transmission cycles are identified, an experimental transmission model will be available to enable us to investigate interactions between E. chaffeensis and its tick host(s). This work is innovative because it questions the dogma that this tick borne pathogen is only transmitted transstadially, but this paradigm will be tested objectively with both intrastadial and transstadial transmission scenarios. In addition to development of a transmission model, the competence of several potential vectors will be determined, which is important for determining whether dogs could be a source of human infection with E. chaffeensis and for accurate diagnosis and prevention of HME. Collectively, these outcomes are expected to have significant positive effects on human (and animal) health, because they will lead to understanding the mechanisms responsible for transmission of E. chaffeensis and perhaps other closely related pathogens among human and domestic hosts.

描述(由申请人提供)：控制人类单核细胞埃立克体病(HME)的方法依赖于更好地了解病原体查菲埃立克体与其扁虱宿主之间的相互作用。已有研究表明，包括Amblyomma、Dermacentor和Ixodes在内的几个硬皮动物属均可自然感染查菲棘球绦虫。虽然在自然暴露的硬体动物中检测到查菲埃希氏杆菌表明这些硬体动物对感染的敏感性，但这并不能证明它们有能力将这种病原体传播到敏感的脊椎动物宿主。可疑媒介(S)重复实验传播节肢动物传播病原体是在合格媒介(S)被定罪之前必须满足的首要标准。这一特定应用的目标是识别扁虱种类和病原体获取情景，从而导致这种病原体的有效实验性传播。该项目的中心假设是，经口感染的成年雄性硬蜱是查菲棘球绦虫的更有效的实验媒介，而不是成年雌性或经途径感染的成年雄性硬蜱。这一中心假设将通过以下具体目标的实现来验证：(1)建立一种足够灵敏的查菲埃希虫的聚合酶链式反应方法，以检测在实验中感染的个体硬蜱中的病原体；(2)查菲埃希虫的经腹和经肠道传播；以及(3)通过成年雄性硬蜱将查菲埃希虫传播给多个宿主。拟议研究的理由是，它将使人们更好地了解在自然条件下不同的扁虱种类和获取情景在传播查菲埃希虫过程中的潜在重要性。此外，一旦确定了有效的传播周期，将有一个实验传播模型可用于研究查菲棘球绦虫与其寄主S之间的相互作用。这项工作具有创新性，因为它质疑了这种扁虱传播的病原体只能经途径传播的教义，但这一范式将在经腹和经途径传播的情况下得到客观检验。除了建立传播模型外，还将确定几个潜在载体的能力，这对于确定狗是否可能成为人类查菲埃菲斯菌感染源以及准确诊断和预防HME非常重要。总体而言，这些结果预计将对人类(和动物)健康产生重大积极影响，因为它们将有助于理解查菲埃希菌以及其他密切相关的病原体在人类和家庭宿主之间传播的机制。