Transmission of Ehrlichia chaffeensis by Adult Ticks

成年蜱传播查菲埃里希体

• 批准号: 6542599
• 负责人: ROGER William STICH
• 金额: $ 26.55万
• 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 2007-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6542599
• 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）：人类单核埃利希体病（HME）是迄今为止在美国报道的最流行的人畜共患埃利希体病，其控制方法依赖于对病原菌恰菲埃利希体与其蜱宿主之间相互作用的更好理解。已经证明，包括Amblyomma、Dermacentor和Ixodes在内的几种硬蜱属可以自然感染查菲埃里希体。尽管在自然暴露的蜱中检测到查菲埃里希体表明这些蜱对感染具有易感性，但并不能证明它们具有将这种病原体传播给易感脊椎动物宿主的能力。可疑媒介对节肢动物传播的病原体进行重复实验性传播是在确定有效媒介之前必须满足的主要标准之一。这一特定应用的目的是确定蜱种类和导致该病原体有效实验传播的病原体获取情况，这是确定查菲埃里希蜱传播机制的重要步骤。该项目的中心假设是，与成年雌性或跨体感染的成年雄性蜱相比，体内感染的成年雄性蜱虫是查菲埃里希体更有效的实验载体。这一中心假设将通过实现以下具体目标进行检验：(1) 开发查菲埃里希体的 PCR 检测方法，其灵敏度足以检测个体实验感染蜱中的病原体；(2) 查菲埃里希体的蜱内和跨体传播；(3) 成年雄性蜱将查菲埃里希体传播到多个宿主。拟议研究的基本原理是，它将有助于更好地了解不同蜱种的潜在重要性以及自然条件下查菲埃里希蜱传播中的获取情况。此外，一旦确定了有效的传播周期，我们将可以使用实验传播模型来研究查菲埃里希体与其蜱宿主之间的相互作用。这项工作具有创新性，因为它质疑这种蜱传病原体只能跨体育场传播的教条，但这种范式将在体育场内和跨体育场传播场景中进行客观测试。除了开发传播模型外，还将确定几种潜在媒介的能力，这对于确定狗是否可能是人类查菲埃里希体感染的来源以及准确诊断和预防 HME 非常重要。总的来说，这些结果预计将对人类（和动物）健康产生显着的积极影响，因为它们将有助于了解查菲埃里希菌以及可能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。