Impact of Distinct Eco-epidemiology on Malaria Drug Resistance in Ghana

描述(申请人提供)：疟疾仍然是全球发病率和死亡率的主要原因，2009年约有781,000人死亡。药物治疗仍然是疟疾控制的主要战略之一。然而，抗药性恶性疟原虫的传播仍然是对根除目标的重大威胁，需要监测新部署的青蒿素联合疗法(ACTS)的疗效。监测最近移除的药物压力也仍然很重要，因为1)敏感的恶性疟原虫(由于抗药性寄生虫的适应成本)可能在一段时间后重新扩大到这些药物，如果不使用的话；2)它们在联合治疗或增加剂量时重新部署的可能性。目前的监测方法包括体内治疗失败的随访，通过短期体外药物试验确定寄生虫的表型敏感性，以及与耐药性相关的分子标记的研究，以监测对恶性疟原虫的药物敏感性。耐药性将如何在一个具有不同生态流行病区的国家传播的问题尚未得到调查。这一点很重要，因为考虑到传播的影响，在各种生态流行病学家的药物疗效监测中可以确定 耐药性传播的“热点”，将被用来最大限度地提高现有哨兵系统的效率，进行疗效监测。这项研究的目的是改进目前的药物敏感性调查方法，并阐明克隆多样性的重要性，克隆多样性是加纳两个主要生态流行病区耐药性监测中传播强度的衡量标准。具体地说，我们将在两个不同的生态区测量和比较抗疟疾药物的临床和寄生虫学效果，确定感染的多样性及其与耐药性的关系，并表征和比较两个生态流行病区已知的耐药性标志物的频率及其与体外药物反应的相关性。这项研究将在加纳森林生态区的Hohoe和加纳萨凡纳海岸地区的Ada进行。将对使用阿莫地喹-青蒿素(AA)或青蒿素卢米安曲林(AL)治疗无并发症疟疾的临床和寄生虫学反应进行单臂前瞻性评估。在疟疾传播高峰期(6-10月)，在两个研究地点的地区医院中，符合研究纳入标准的总共200名/年(四年内800名)患有简单疟疾的儿童将被纳入研究。这些儿童将在现场按照护理标准接受AA或AL治疗，并进行28天的监测。当我们招募第100个孩子时，将为该网站进行收集。后续工作将包括固定的体检和相应的临床和实验室检查。当孩子没有按预定时间返回时，会派研究人员到孩子家里进行跟踪，尽量减少损失。根据这些评估的结果，这些儿童将被归类为治疗失败(早期、临床晚期、寄生虫晚期)或反应充分(两种类型的治疗都没有出现)。 聚合酶链式反应分析将用于区分治疗失败导致的真正复发和再感染事件(msp1和msp2分型)。治疗前采集的样本的体外药物测试将用于通过测量IC50来确定药物反应的非临床表型。单拷贝恶性疟原虫疫苗候选抗原(MSP1、MSP2和CSP)的基因多态将被用来评估MOI，与耐药性相关的可能的分子标记将被表征以确定它们的频率及其与耐药表型和MOI的关系。此外，将每年对每个研究区域的100名学童进行横断面调查(从两个生态区抽取200个样本，并在四年内抽取800个样本)，以评估人口感染的多样性。我们将检验这样一种假设，即在疟疾高传播强度(森林生态区)时，耐药寄生虫的流行率会随着多克隆感染而下降，而在疟疾传播低时(沿海萨凡纳生态区)，抗药性寄生虫的流行率会随着克隆性感染而增加。

DESCRIPTION (provided by applicant): Malaria remains a leading cause of morbidity and mortality worldwide, killing approximately 781,000 people in 2009. Drug therapy remains one of the major strategies of malaria control. The spread of drug resistant P. falciparum, however, remains a major threat to the goal of eradication, requiring monitoring of the efficacy of the newly deployed artemisinin based combination treatments (ACTs). Monitoring of recently removed drug pressures also remains important given 1) the possible re-expansion of susceptible P. falciparum (as a result of a fitness cost on resistance parasites) to these drugs after a period if unused and 2) their potential for redeployment in combination therapy or in increased doses. Current monitoring methods include follow up of therapeutic failures in vivo, phenotypic determination of parasite sensitivity by short-term ex vivo drug testing and studies of molecular markers associated with drug resistance are surveyed to monitor drug sensitivity to P. falciparum. The question of how resistance will spread in a country with distinct eco-epidemiological zones has not been investigated. This is important because accounting for the effects of transmission in the various eco- epidemiologist in drug efficacy monitoring can identify "hotspots" for the spread of resistance that will be used to maximize the efficiency of existing sentinel systems for efficacy monitoring. The goal of this study is to improve current methods for surveying drug sensitivity, and elucidate the importance of clonal multiplicity, a measure of transmission intensity on the surveillance of drug resistance in two major eco-epidemiological zones of Ghana. Specifically, we will measure and compare the clinical and parasitological efficacy of anti-malarial drugs in two distinct ecological zones, determine the multiplicity of infections and its association with drug resistance and characterize and compare the frequency of known drug resistance markers in two eco-epidemiological zones and their correlations with ex vivo drug response. The study will be conducted in Hohoe, in the Forest ecological zone and Ada in the Coastal Savannah zone of Ghana. A one-arm prospective evaluation of clinical and parasitological responses to treatment for uncomplicated malaria with Amodiaquine -Artemisinin (AA) or Artemisinin Lumifantrine (AL) will be conducted. A total of 200 children/year (800 over four years) with uncomplicated malaria in District hospitals of the two study sites who meet the study inclusion criteria will be enrolled during the peak of the malaria transmission season (June-October). These children will be treated on site with AA or AL following standard of care and monitored for 28 days. When we recruit the 100th child, collection will be done for that site. The follow-up will consist of a fixed schedule of check-up visits and corresponding clinical and laboratory examinations. When a child does not return to a scheduled visit, a research staff will be sent to the child's house to minimize losses to follow-up. On the basis of the results of these assessments, the children will be classified as having therapeutic failure (early, late clinical, ad late parasitological) or an adequate response (not presenting neither type of therapeutic failure). PCR analysis will be used to distinguish between a true recrudescence due to treatment failure and episodes of re-infection (msp1 and msp2 typing). Ex vivo drug testing of samples collected before treatment will be use to determine non-clinical phenotypes of drug response by measuring IC50.s. Polymorphisms in single copy P. falciparum vaccine candidate antigens (msp1, msp2 and csp) will be genotyped to assess MOI and putative molecular markers associated with drug resistance will be characterised to determine their frequency and association with drug resistance phenotypes and MOI. In addition, an annual cross-sectional survey of 100 school children per study area (200 samples from the two ecological zones and, 800 samples over a four year period) will be recruited for multiplicity of infection (MOI) assessment of the population. We will test the hypothesis that the prevalence of resistant parasites will decrease with polyclonal infections at high malaria transmission intensity (Forest ecological zone) and increase with clonal infections at low malaria transmission (Coastal Savannah ecological zone).