Malaria elimination in Sub-Saharan Africa: essential tools and identifiable targets

虽然疟疾仍然影响着世界人口的很大一部分，但在过去几年里，疟疾已大幅下降，这也是由于扩大了干预措施，如用杀虫剂处理过的蚊帐。撒哈拉以南非洲国家，包括疟疾负担最重的冈比亚，也出现了这种下降。在1950年代的上一次尝试之后，疟疾可以减少到不再是一个主要的公共卫生问题，甚至可以消除的想法再次被提出。放弃这一做法主要有两个原因：缺乏财政支持和采用单一战略，没有考虑到疟疾传播的极端多变性。现在人们认识到，支持任何消除努力所需的知识是有限的，这方面的新尝试应该得到强有力的研究部分的支持。拟在冈比亚开展的这一研究方案旨在为撒哈拉以南非洲国家疟疾控制方案提供必要的知识和工具，以进一步消除疟疾。冈比亚是开展拟议研究方案的理想地点，因为1。该国在减少疟疾负担方面极为成功，并打算进一步减少疟疾负担; 2. MRC实验室拥有所需的专业知识，先进的技术平台和必要的国际合作，以实现该计划的目标。这两个因素的结合在西非是独一无二的，为开展研究方案提供了一个黄金机会，该方案可对撒哈拉以南非洲开展消除工作的方式产生深远影响。活动分为两个平行和互补的部分：一部分旨在了解疟疾传播的动态以及为什么在几公里范围内会有很大差异的原因;另一部分旨在改进诊断测试，以查明感染疟疾但其他方面健康的人（疟疾携带者）。对于前者，将对12个村庄的人口进行三个传播季节的密集跟踪，以了解谁是疟疾携带者以及感染如何在人口中传播。将收集关于病媒种群的信息，包括是否存在杀虫剂抗药性，以及关于人类行为的信息，以部分解释研究村庄之间可能存在的差异。在研究结束时，我们将更好地了解疟疾寄生虫是如何传播的，以及尽管预防和治疗措施的覆盖率很高，但维持一年到另一年传播的重要决定因素是什么。我们将尝试两种方法，一种旨在开发易于使用的分子测试，可以检测大多数感染个体，另一种是通过检测寄生虫或宿主的蛋白质来寻找感染的“标记”，这些蛋白质只能在感染个体中找到。后者可以提供必要的知识，以开发更敏感的测试。这项研究计划的结果将对任何愿意消除疟疾的撒哈拉以南非洲国家具有重要意义。将通过国际和区域会议以及国际同行审查的出版物和通讯传播这些文件。此外，通过冈比亚国家疟疾控制方案，可以通过当地新闻媒体以更广泛的公众可以获得的形式传播结果。

Though still affecting an important proportion of the world population, malaria has declined substantially in the last few years, thanks also to the scale up of interventions such as bed nets treated with insecticide. Such decrease has been observed also in sub-Saharan African countries, including The Gambia, where the malaria burden is the highest. The idea that malaria can be reduced at the point where it would not be a major public health problem anymore or would even be eliminated has been re-introduced again after the previous attempt in the 1950s. This was abandoned mainly for two reasons: lack of financial support and use of a single strategy that did not take into account the extreme variability of malaria transmission. It is now recognised that the knowledge needed to support any elimination effort is limited and that a new attempt in this direction should be supported by a strong research component. This proposed research program to be carried out in The Gambia aims at providing sub-Saharan African National Malaria Control Programs with the necessary knowledge and tools to move farther, towards malaria elimination. The Gambia is the ideal place to carry out the proposed research program because 1. The country has been extremely successful in reducing the malaria burden and aims at reducing it further; 2. The MRC laboratories have the required expertise, the advanced technological platform and the necessary international collaborations to achieve the program's objectives. The combination of these two factors is unique in West Africa and offers a golden opportunity to carry out a research programme that can have a profound influence on the way elimination efforts will be implemented in sub-Saharan Africa. Activities are divided into two parallel and complementary sections: one section aims at understanding the dynamics of malaria transmission and the reasons why this can substantially differ within few kilometres; the other section will aim at improving diagnostic tests able to identify malaria infected but otherwise healthy people (malaria carriers). For the former, the populations of 12 villages will be intensively followed up for 3 transmission seasons to understand who the malaria carriers are and how the infection spreads across the populations. Information on the vector population, including the presence of insecticide resistance, and on the human behaviour will be collected to partly explain the likely differences between the study villages. At the end of the study we will have a better understanding on how the malaria parasites spread and what are the important determinants that maintain transmission from one year to the other, despite the high coverage of preventive and curative measures.Concerning diagnostic tests, the currently available tests that can be used in the field cannot detect a proportion of infected people that contributes in maintaining transmission. We will try two approaches, one aiming at developing easy-to-use molecular test that can detect most infected individuals, and the other looking at "markers" of infection by detecting parasite's or host's proteins that can be found only in infected individuals. The latter could provide the knowledge necessary to develop a more sensitive test. The results of this research program will be important for any sub-Saharan African country willing to go towards elimination of malaria. They will be disseminated through international and regional conferences, and by international peer-reviewed publications and communications. In addition, through the Gambian National Malaria Control Program, results may be disseminated through the local press in a form accessible to a wider public.