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Life on the edge: tackling human African trypanosomiasis on the edge of wilderness areas

边缘生活：在荒野地区边缘应对人类非洲锥虫病

基本信息

批准号：
BB/L019035/1
负责人：
Stephen John Torr
金额：
$ 77.99万
依托单位：
Liverpool School of Tropical Medicine
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2014
资助国家：
英国
起止时间：
2014 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FL019035%2F1
关键词：
Life edge tackling human African

项目摘要

Boundary areas between different populations are the crucial places where pathogens spill over from one population to the other, and present a key risk for the emergence of new pathogens, or invasion by existing pathogens. An important example of this type of boundary are the edges of wilderness areas, where pathogens present naturally in wild animals can spill over to infect people and livestock living in the surrounding areas. In sub-Saharan Africa, this scenario often affects human populations with few economic resources. The proximity of vulnerable populations to areas harbouring pathogens provides a technical and moral challenge: how can biodiversity and economically productive wilderness areas be preserved without threatening the health and livelihoods of vulnerable people? Our proposal will study the interaction between humans, livestock and wildlife and the role of this transition zone in the transmission of trypanosomes at the edge of the Serengeti National Park in Tanzania. These single-celled parasites are transmitted by the bite of tsetse flies. They do not cause any overt disease in wild animals within the Park, but humans bitten by tsetse infected with a particular species of trypanosome can develop sleeping sickness, a potentially fatal disease for which there is no preventative vaccine or drug. Other species of trypanosome also present in wild animals can cause a wasting, and ultimately fatal, disease in livestock. Tsetse flies are highly mobile and can move from their natural habitat within the park to infect humans and livestock in surrounding areas. In east and southern Africa, the species of tsetse that transmit trypanosomes usually feed on wild animals rather than humans. However, changing housing and farming practices reduce the availability of wild hosts to tsetse and increase the risk of humans being bitten by infected flies. It is estimated that 12 million people in east and southern Africa are at risk of sleeping sickness and the preservation of wilderness areas present a chronic and intractable source of infection. Preliminary data suggest however that there are restricted hotspots of disease risk, particularly at the edges of national parks, and that the application of modern methods of tsetse control to these hotspots will eliminate sleeping sickness foci. To assess whether focussed control of tsetse is effective, we will develop mathematical models of the transmission of trypanosomes in the transition zone from wildlife-dominated areas on the park boundaries through to livestock-dominated areas outside the parks. The models will enable us to predict the likely extent, duration and cost of interventions required to interrupt the transmission of trypanosomes at boundary areas. Parameter values for the models will be obtained using a combination of existing and new data on (i) the distribution, abundance, structure and infection status of tsetse populations, (ii) the densities of wildlife and livestock hosts, (iii) the number of livestock infected with trypanosomes, (iv) the composition and population genetics of the trypanosome populations and (v) the vegetational changes that occur at the boundary of the Serengeti National Park. The models will be validated by comparing the observed and predicted patterns of infection in the study area. We will then use the models to predict the likely impact of various control interventions, and identify which are the most appropriate control measures for livestock keepers, NGOs and government agencies concerned with controlling trypanosomes at different distances from the boundaries of protected areas. The project's outputs will assist Tanzania and other countries affected by tsetse-borne trypanosomiases to develop cost-effective strategies for managing diseases at the transition zone between wildlife-protected and livestock-keeping areas.

不同种群之间的边界区域是病原体从一个种群溢出到另一个种群的关键场所，并且是新病原体出现或现有病原体入侵的关键风险。这种边界的一个重要例子是荒野地区的边缘，野生动物中自然存在的病原体可能会溢出来感染周围地区的人和牲畜。在撒哈拉以南非洲地区，这种情况经常影响经济资源匮乏的人口。脆弱人群与病原体藏匿地区的接近带来了技术和道德挑战：如何在不威胁脆弱人群的健康和生计的情况下保护生物多样性和具有经济生产力的荒野地区？我们的提案将研究人类、牲畜和野生动物之间的相互作用，以及这个过渡区在坦桑尼亚塞伦盖蒂国家公园边缘锥虫传播中的作用。这些单细胞寄生虫通过采采蝇叮咬传播。它们不会在公园内的野生动物中引起任何明显的疾病，但被感染特定锥虫种类的采采蝇叮咬的人类可能会患上昏睡病，这是一种可能致命的疾病，目前还没有预防疫苗或药物。野生动物中也存在其他种类的锥虫，可导致牲畜消耗性疾病，并最终致命。采采蝇具有高度流动性，可以从公园内的自然栖息地转移到感染周边地区的人类和牲畜。在东部和南部非洲，传播锥虫的采采蝇物种通常以野生动物而不是人类为食。然而，住房和耕作方式的改变减少了采采蝇野生宿主的可用性，并增加了人类被受感染苍蝇叮咬的风险。据估计，东非和南部非洲有 1200 万人面临昏睡病的风险，而荒野地区的保护则成为慢性且难以治愈的感染源。然而，初步数据表明，疾病风险热点地区有限，特别是在国家公园边缘，对这些热点地区应用现代采采蝇控制方法将消除昏睡病疫源地。为了评估对采采蝇的集中控制是否有效，我们将开发锥虫在公园边界内野生动物为主的区域到公园外牲畜为主的区域之间传播的数学模型。这些模型将使我们能够预测中断边界地区锥虫传播所需的干预措施的可能范围、持续时间和成本。模型的参数值将通过现有数据和新数据的组合来获得：(i) 采采蝇种群的分布、丰度、结构和感染状况，(ii) 野生动物和牲畜宿主的密度，(iii) 感染锥虫的牲畜数量，(iv) 锥虫种群的组成和种群遗传学，以及 (v) 边界发生的植被变化。塞伦盖蒂国家公园。将通过比较研究区域观察到的和预测的感染模式来验证模型。然后，我们将使用这些模型来预测各种控制干预措施可能产生的影响，并确定哪些是最适合牲畜饲养者、非政府组织和政府机构在距保护区边界不同距离处控制锥虫的控制措施。该项目的成果将协助坦桑尼亚和其他受采采蝇锥虫病影响的国家制定具有成本效益的战略，以管理野生动物保护区和牲畜饲养区之间过渡区的疾病。