The role of heartwater (Ehrlichia ruminantium infection) and other tick-borne pathogens in Acute Camel Death Syndrome in Kenya

心水（反刍埃里希体感染）和其他蜱传病原体在肯尼亚急性骆驼死亡综合症中的作用

• 批准号: BB/S004890/1
• 负责人: Lesley Bell-Sakyi
• 金额: $ 12.84万
• 依托单位: University of Liverpool
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2019
• 资助国家: 英国
• 起止时间: 2019 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FS004890%2F1
• 关键词: role; heartwater; Ehrlichia; ruminantium; infection

Dromedary camels are important food-producing animals in northern Kenya and vital for the economy, food security and well-being of pastoralist communities. Their population is steadily increasing year-on-year and stood at over 3.2 million in 2016. The Kenyan camel meat and milk industry is worth approximately US$11 million annually. Acute Camel Death Syndrome (ACDS) is an emerging disease of unknown cause affecting camel herds in parts of northern Kenya. Up to 100% of affected adult camels can die without treatment. Unlike other camel diseases that are well-recognised by local pastoralists, ACDS is a new disease for which Kenyan camel keepers have no vernacular name. Clinical and post-mortem signs show strong similarities to heartwater, a tick-borne disease of sheep, goats and cattle that is endemic throughout sub-Saharan Africa, but has only been described in camels in other parts of Africa on three occasions in the past 60 years. Affected camel herds may be heavily infested with ticks, and the causative agent of heartwater, the intracellular bacterium Ehrlichia ruminantium, has been detected in ticks removed from camels affected by ACDS. However this does not prove that ACDS is a manifestation of heartwater in camels; other tick-borne pathogens (TBP) may be involved in the syndrome.It is essential to identify the causative agent of ACDS so that effective preventive and/or control measures can be implemented.To investigate the role of heartwater and other TPB in ACDS, we propose to carry out a broad-spectrum survey of camels, sheep that graze alongside them, and ticks infesting both species, in areas where ACDS outbreaks have occurred. As controls, we will similarly sample camels, sheep and ticks in areas where ACDS has not been reported. We will interview camel keepers to determine their prior knowledge of ACDS and how it is distinct from other camel diseases with which they are familiar, and to establish disease incidence, symptoms, post mortem signs and concurrent levels of tick infestation that they have observed during outbreaks. We will collect blood and serum samples and ticks from camels and co-grazing sheep; blood samples will be screened for presence of E. ruminantium and other TBP indicating current infection and serum samples will be tested for antibodies to E. ruminantium and other TBP indicating previous exposure. Ticks will be screened for infection with E. ruminantium and other TBP to determine the range of pathogens circulating in the sample areas. We will attempt to isolate strains of the different pathogens by culturing them in bovine and tick cell lines; gene sequences of isolated novel strains will be compared with those of known strains from other hosts to look for differences that might explain the emergence of ACDS as a new camel disease. If there is an outbreak of ACDS in any of our study areas during the project, we will collect clinical and post-mortem samples from affected camels and process them in the same way as the survey samples. We will bank aliquots of the camel and tick samples in cryostorage, thereby creating a resource for use in future studies on ACDS and by scientists researching other factors affecting camel health.An important element of our project will be capacity-building relating to ACDS and more generally to camel health in Kenya. Using the knowledge gained from our field and laboratory studies, we will formulate protocols for diagnosis, treatment and control of ACDS, including hands-on training in appropriate sampling techniques and proper storage and transport of samples to the laboratory. In addition, we will provide the opportunity and support for a Kenyan MSc student to carry out their research project focussing on a particular aspect of our proposed study.

单峰骆驼是肯尼亚北方重要的粮食生产动物，对牧民社区的经济、粮食安全和福祉至关重要。他们的人口逐年稳步增长，2016年超过320万。肯尼亚的骆驼肉和牛奶产业每年价值约1100万美元。急性骆驼死亡综合症是一种新出现的疾病，原因不明，影响肯尼亚北方部分地区的骆驼群。高达100%的受影响成年骆驼可以在不治疗的情况下死亡。与当地牧民熟知的其他骆驼疾病不同，ACDS是一种新的疾病，肯尼亚骆驼饲养者没有方言名称。临床和尸检迹象显示与心水病有很大的相似之处，心水病是一种绵羊、山羊和牛的蜱传疾病，在整个撒哈拉以南非洲地区流行，但在过去60年里，非洲其他地区的骆驼只出现过三次。受影响的骆驼群可能受到蜱虫的严重侵扰，在从受ACDS影响的骆驼身上取下的蜱虫中检测到了心水的病原体，即细胞内细菌反刍埃里希体。然而，这并不能证明ACDS是骆驼心水的表现;为了研究心水和其他蜱传病原体在急性呼吸窘迫综合征中的作用，我们建议对骆驼、与它们一起放牧的绵羊、和蜱虫侵染这两个物种，在ACDS爆发的地区发生。作为对照，我们将在未报告急性腹泻病的地区对骆驼、绵羊和蜱进行类似的采样。我们将采访骆驼饲养员，以确定他们对ACDS的先前知识以及它与他们熟悉的其他骆驼疾病的区别，并确定疾病的发病率，症状，死后体征和他们在爆发期间观察到的蜱虫感染水平。我们将从骆驼和共同放牧的绵羊中收集血液和血清样本以及蜱虫;血液样本将被筛选是否存在E。反刍动物和其他TBP表明目前的感染和血清样品将测试抗体的E。反刍动物和其他TBP表明以前的接触。将对蜱进行E.反刍动物和其他TBP，以确定在样品区循环的病原体的范围。我们将尝试通过在牛和蜱细胞系中培养来分离不同病原体的菌株;将分离的新菌株的基因序列与来自其他宿主的已知菌株的基因序列进行比较，以寻找可能解释ACDS作为一种新的骆驼疾病出现的差异。如果在项目期间，我们的任何研究地区爆发了急性腹泻病，我们将从受影响的骆驼中收集临床和死后样本，并以与调查样本相同的方式处理这些样本。我们将把骆驼和蜱虫样本的等分试样储存在冷冻库中，从而为今后关于非洲荒漠化综合征的研究以及研究影响骆驼健康的其他因素的科学家提供一种资源，我们项目的一个重要内容将是与非洲荒漠化综合征有关的能力建设，更广泛地说，是肯尼亚骆驼健康的能力建设。利用我们从现场和实验室研究中获得的知识，我们将制定ACDS的诊断、治疗和控制方案，包括适当采样技术的实践培训以及样本的正确储存和运输到实验室。此外，我们将为肯尼亚硕士学生提供机会和支持，以开展他们的研究项目，专注于我们拟议研究的特定方面。

项目成果

Detection of Antibodies to Ehrlichia spp. in Dromedary Camels and Co-Grazing Sheep in Northern Kenya Using an Ehrlichia ruminantium Polyclonal Competitive ELISA.

• DOI: 10.3390/microorganisms10050916
• 发表时间: 2022-04-27
• 期刊: Microorganisms
• 影响因子: 4.5

Ticks and tick-borne pathogens associated with dromedary camels (Camelus dromedarius) in northern Kenya

肯尼亚北部与单峰骆驼（Camelus dromedarius）相关的蜱虫和蜱传病原体

• DOI: 10.20944/preprints202106.0170.v1
• 发表时间: 2021
• 作者: Getange D