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ENABLES: Enabling Livestock-keepers to Eliminate Sleeping Sickness

使：使畜牧业者能够消除昏睡病

基本信息

批准号：
BB/S01375X/1
负责人：
Stephen John Torr
金额：
$ 49.33万
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：
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%2FS01375X%2F1
关键词：
ENABLES Enabling Livestock keepers Eliminate

项目摘要

Edges of wilderness areas, where pathogens occurring naturally in wild animals can spill over to infect people and livestock in surrounding areas, are a key risk for the emergence of new pathogens and spread of existing ones. In sub-Saharan Africa, this scenario often affects poor and marginalised human populations. The proximity of vulnerable populations to these areas provides a technical and ethical challenge: how can biodiversity and economically productive wilderness areas be preserved without threatening the health and livelihoods of vulnerable people? ENABLES builds on our work at the edge of the Serengeti National Park in Tanzania where tsetse flies transmit trypanosomes. These single-celled parasites do not cause any overt disease in wild animals, but do cause a disease called Nagana in livestock. Humans bitten by tsetse infected with a particular species of trypanosome can develop sleeping sickness (Rhodesian human African trypanosomiasis, r-HAT), an acute and fatal disease for which there is no preventative vaccine or drug. About 12 million people in east and southern Africa are at risk of r-HAT and the preservation of wilderness areas presents a chronic and intractable source of infection. Only Botswana has been able to solve the problem of r-HAT permanently by eradicating tsetse from the Okavango wilderness area through large-scale (~15,000 km2) aerial spraying. This complex and expensive solution is not feasible for most poor communities living on the edge of wilderness areas. Our work in Serengeti suggests that livestock-keepers are preventing the spread of r-HAT by simply applying pyrethroid insecticides to their cattle. They do this to control the ticks and tsetse that carry livestock diseases (East Coast Fever, Nagana) but this cheap (~$6/animal/year) and easy method also interrupts transmission of r-HAT. By treating livestock to prevent animal diseases, livestock-keepers are protecting local people from r-HAT. Other countries have tried but failed to encourage widespread use of pyrethroids by livestock-keepers as part of a One Health approach against r-HAT. Uptake in Tanzania appears to be stimulated, at least in part, by a government subsidy on the price of pyrethroids. While our discoveries in Serengeti offer the exciting prospect of a One Health solution to r-HAT, we do not know (i) how widespread pyrethroid use is in different livestock systems, (ii) how generally applicable this approach is, and (iii) what conditions make farmer-led control likely and effective. ENABLES will test the hypothesis that national policies to promote use of pyrethroids by livestock-keepers have led to large-scale control of human and animal trypanosomiasis. To achieve this, we will first use satellite data to predict where tsetse are abundant, and then test the predictions by comparing the observed and expected number of tsetse caught in traps placed at various sites. Using a validated model of tsetse abundance, we will identify 'hotspots' where transmission is predicted to be high.In selected 'hotspots' from areas where different livestock systems (pastoralist, mixed crop-livestock, zero-grazing) predominate, we will test cattle for infection with trypanosomes and the presence of pyrethroids. We will conduct a questionnaire survey of herd owners about the decision-making underpinning methods used to control tsetse- and tick-borne diseases. We will also interview owners of veterinary outlets, national distributors of veterinary medicines and government officials to gain insights into the pyrethroid supply chain.Finally, we will use models to integrate data on the density of tsetse, prevalence of trypanosomes and use of pyrethroids to quantify the epidemiological benefit of pyrethroid-treated cattle. Empirical findings and models will form the basis of a toolbox to assist Tanzania and other countries to formulate evidence-based policies and practices for the sustainable control of sleeping sickness.

在荒野地区的边缘，自然发生在野生动物身上的病原体可以溢出来感染周围地区的人和牲畜，这是出现新病原体和传播现有病原体的关键风险。在撒哈拉以南非洲，这种情况往往影响到贫穷和边缘化的人口。脆弱人群靠近这些地区，这在技术和伦理上提出了挑战：如何在不威胁脆弱人群健康和生计的情况下保护生物多样性和经济上富有生产力的荒野地区？enable建立在我们在坦桑尼亚塞伦盖蒂国家公园边缘的工作基础上，在那里采采蝇传播锥虫。这些单细胞寄生虫不会在野生动物中引起任何明显的疾病，但确实会在牲畜中引起一种称为Nagana的疾病。被感染了特定种类锥虫的采采蝇叮咬的人可患昏睡病（罗得西亚人非洲锥虫病，r-HAT），这是一种急性和致命的疾病，目前尚无预防疫苗或药物。东非和南部非洲约有1200万人面临r-HAT的风险，而对荒野地区的保护是一种慢性和棘手的感染源。只有博茨瓦纳能够通过大规模（约15,000平方公里）空中喷洒消灭奥卡万戈荒野地区的采采蝇，从而永久解决r-HAT问题。这种复杂而昂贵的解决方案对于生活在荒野地区边缘的大多数贫困社区来说是不可行的。我们在塞伦盖蒂的工作表明，牲畜饲养者通过简单地给他们的牛施用拟除虫菊酯杀虫剂来防止r-HAT的传播。他们这样做是为了控制携带牲畜疾病的蜱虫和采采蝇（东海岸热，Nagana），但这种便宜（~ 6美元/只动物/年）和简单的方法也阻断了r-HAT的传播。通过治疗牲畜以预防动物疾病，牲畜饲养者正在保护当地人民免受r-HAT的侵害。其他国家也曾尝试鼓励牲畜饲养者广泛使用拟除虫菊酯类杀虫剂，但未能将其作为“同一个健康”措施的一部分。在坦桑尼亚，政府对拟除虫菊酯类杀虫剂价格的补贴至少在一定程度上刺激了对其的吸收。虽然我们在塞伦盖蒂的发现为“同一个健康”解决r-HAT提供了令人兴奋的前景，但我们不知道(i)拟除虫菊酯类杀虫剂在不同牲畜系统中的使用有多广泛，（ii）这种方法的普遍适用性如何，以及（iii）在什么条件下农民主导的控制可能和有效。enable将检验这样一种假设，即促进牲畜饲养者使用拟除虫菊酯类杀虫剂的国家政策导致了人类和动物锥虫病的大规模控制。为了实现这一目标，我们将首先使用卫星数据来预测采采蝇丰富的地方，然后通过比较在不同地点放置的陷阱中捕获的观察到的采采蝇和预期的采采蝇数量来测试预测。利用一个经过验证的采采蝇丰度模型，我们将确定预计传播率很高的“热点”。在不同牲畜系统（畜牧、混合作物-牲畜、零放牧）占主导地位的地区选定的“热点”地区，我们将检测牛是否感染锥虫和是否存在拟除虫菊酯。我们将对畜群所有者进行问卷调查，了解控制采采和蜱传疾病的决策基础方法。我们还将采访兽医销售点的所有者、全国兽药分销商和政府官员，以深入了解拟除虫菊酯类杀虫剂的供应链。最后，我们将使用模型整合采采蝇密度、锥虫流行率和拟除虫菊酯使用数据，以量化拟除虫菊酯处理牛的流行病学效益。经验调查结果和模型将构成工具箱的基础，以协助坦桑尼亚和其他国家制定以证据为基础的政策和做法，以实现对昏睡病的可持续控制。