STRESS-MALAWI: Strengthening Resilience against Sleeping Sickness in Malawi

预测、检测和应对已知和新发传染病的暴发是一个世界性问题，特别是在卫生系统脆弱的国家。在撒哈拉以南非洲，已有的和新出现的人畜共患病(如埃博拉)的暴发往往起源于偏远的荒野地区，病原体在野生宿主之间传播，基本上未被发现，几乎没有人类病例。由于鲜为人知的原因，这些病原体的传播动态可能会改变，当疾病蔓延到邻近的人和家畜种群时会爆发。罗得西亚人非洲锥虫病(RHAT)由采采蝇传播的布氏锥虫引起，是一种与东部和南部非洲保护区有关的人畜共患疾病。在2019-2020年，马拉维经历了犀牛病例的激增。在短短三个月的时间里，病例数量是前十年年平均值的三倍，大多数病例来自两个国家公园附近的社区。激增的根本原因尚不确定，但潜在的原因包括环境变化导致采采蝇生态和行为的变化，和/或出现了一种毒力强的布氏锥虫。目前，马拉维对犀牛的控制在很大程度上依赖于被动发现和治疗病例。目前还没有疫苗或药物来预防犀牛，保护人类的唯一方法是控制采采蝇，然而，在国家公园内这样做的成本高得令人望而却步，而且后勤方面也很复杂。需要更多负担得起和可持续的战略，将采采树从定居地区移走，并将它们限制在公园内。Stress-马拉维项目的总体目标是测试这样一种假设，即生活在保护区边缘的社区可以通过将采采树控制工作集中在维持采采树种群叮咬人类的关键生态区来降低Rat的风险。这些区域很可能是保护区的边缘，在那里密集的自然植被和丰富的野生宿主使大量的采采树保持在相对接近定居地的位置。我们将专注于马拉维北部的瓦瓦扎沼泽野生动物保护区和周围的农业区，进行实证和模型研究，以量化RAT的潜在空间和时间驱动因素，并确定2019年病例激增的潜在原因。这些研究的结果将使我们能够设计和提供一种具有成本效益和空间信息的采采热控制策略，其中将部署吸引和杀死采采蝇的杀虫剂处理靶标，以保护社区免受采采蝇的侵袭。为了实现我们的目标，我们将：-首先，制定和实施采采集抽样战略，以量化采采集和锥虫在自然保育区和农业区交界处的种群动态。采采集将沿着界面上的横断面进行采样，使用卫星和无人机图像同时绘制土地覆盖图将量化采采集丰度和植被之间的关系。第二，量化人类在室外和建筑物内移动所吸引的采采集的数量和类型，从而确定人们可能被叮咬的地点和时间。第三，确定罗德氏锥虫的传播潜力是否由于一种新的毒力寄生虫的出现而增加。最后，我们将整合来自1-3的知识，在Vwaza沼泽保护区的界面上设计和实施媒介控制战略。我们的研究结果将有助于马拉维和东部和南部非洲其他国家制定监测和控制犀牛的战略。更广泛地说，我们项目产生的数据、模型、锥虫基因组和方法将有助于控制与荒野地区相关的现有和新兴媒介人畜共患病的循证战略。

Predicting, detecting and responding to outbreaks of known and emerging infectious diseases pose a worldwide problem, particularly in countries where the health system is fragile. In sub-Saharan Africa, outbreaks of established and emerging (e.g. Ebola) zoonotic diseases often have their origins in remote wilderness areas where pathogens circulate largely undetected between wild reservoir hosts and with few human cases. For reasons poorly understood, the transmission dynamics of these pathogens can change and outbreaks occur as the disease spills over into neighbouring populations of humans and livestock.Rhodesian Human African Trypanosomiasis (rHAT), caused by Trypanosoma brucei rhodesiense transmitted by tsetse flies, is a zoonotic disease associated with conservation areas of East and Southern Africa. In 2019-20, Malawi experienced a surge of rHAT cases. In a period of just three months, the number of cases was triple the annual mean for the previous decade, with most cases coming from communities located near two national parks. The underlying causes of the surge are uncertain but potential causes include changes in the ecology and behaviour of tsetse as a consequence of environmental changes, and/or the emergence of a virulent strain of Trypanosoma brucei rhodesiense. Currently, control of rHAT in Malawi relies largely on passive detection and treatment of cases. There are no vaccines or drugs to prevent rHAT and the only way of protecting people is by controlling tsetse flies, however, to do this across a national park is prohibitively expensive and logistically complex. More affordable and sustainable strategies which remove tsetse from settled areas and confine them to the park are needed.The overall goal of the STRESS-MALAWI project is to test the hypothesis that risk of rHAT for communities living on the edge of conservation areas can be reduced by focusing tsetse control efforts on the key ecological zones which sustain the tsetse populations biting humans. These zones are likely to be the edges of a conservation area where dense natural vegetation and an abundance of wild hosts sustain high numbers of tsetse relatively close to settlements.Focusing on the Vwaza Marsh Wildlife Reserve in northern Malawi, and the surrounding farming areas, we will undertake empirical and modelling studies to quantify the underlying spatial and temporal drivers of rHAT and identify potential causes of the 2019-surge in cases. Findings from these studies will allow us to design and deliver a cost-effective and spatially-informed tsetse control strategy in which insecticide-treated targets, which attract and kill tsetse, will be deployed to protect communities from rHAT. To achieve our goal, we will:-First, develop and implement a tsetse sampling strategy to quantify the population dynamics of tsetse and trypanosomes across the interface of conservation and agricultural areas. Tsetse will be sampled along transects across the interface and simultaneous mapping of landcover using satellite and drone imagery will quantify the relationship between tsetse abundance and vegetation.Second, quantify the numbers and type of tsetse attracted to humans moving outdoors and within buildings and hence identify where and when people are likely to be bitten.Third, determine whether the transmission potential of T. b. rhodesiense has increased due to the emergence of a new virulent strain of parasite.Finally, we will integrate knowledge from 1-3 to design and implement a vector control strategy at the interface of the Vwaza Marsh Reserve.Our findings will contribute to the development of a strategy for monitoring and control of rHAT in Malawi and other countries in East and Southern Africa. More generally, the data, models, trypanosome genomes and methods produced by our project will contribute to evidence-based strategies for controlling existing and emerging vector-borne zoonoses associated with wilderness areas.