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

描述（由申请人提供）：疟疾仍然是世界范围内发病率和死亡率的主要原因，2009年造成约781，000人死亡。药物治疗仍然是控制疟疾的主要战略之一。然而，抗药性恶性疟原虫的传播仍然是对根除目标的一个主要威胁，需要监测新部署的青蒿素类复方疗法的疗效。监测最近移除的药物压力也仍然很重要，因为1）如果不使用这些药物，在一段时间后，敏感的恶性疟原虫可能会对这些药物重新扩张（由于耐药寄生虫的适应性成本），以及2）它们在联合治疗中重新部署或增加剂量的潜力。目前的监测方法包括跟踪体内治疗失败，通过短期体外药物试验确定寄生虫敏感性的表型，以及与药物抗性相关的分子标记物的研究，以监测恶性疟原虫的药物敏感性。抗药性如何在一个具有不同生态流行病学区的国家传播的问题尚未得到调查。这一点很重要，因为考虑到在各种生态流行病学中传播的影响，在药物疗效监测中可以确定 耐药性传播的“热点”，将用于最大限度地提高现有哨兵系统的效力监测效率。本研究的目的是改善目前的方法调查药物敏感性，并阐明克隆多样性的重要性，在加纳的两个主要的生态流行病学区的耐药性监测的传播强度的措施。具体而言，我们将测量和比较抗疟疾药物在两个不同的生态区的临床和寄生虫学疗效，确定感染的多重性及其与耐药性的关联，并表征和比较两个生态流行病学区的已知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霍霍和沿海萨凡纳区的阿达进行。将对阿莫地喹-青蒿素（AA）或青蒿素光泛群（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价。在疟疾传播高峰期（6月至10月），将在两个研究中心的地区医院每年招募200名（4年内800名）符合研究入选标准的无并发症疟疾儿童。这些儿童将按照标准治疗在研究中心接受AA或AL治疗，并监测28天。当我们招募第100名儿童时，将为该网站进行收集。随访将包括固定的检查访视时间表和相应的临床和实验室检查。当一个孩子没有回到预定的访问，研究人员将被派往孩子的房子，以尽量减少损失的后续行动。根据这些评估的结果，儿童将被分类为治疗失败（早期、晚期临床、晚期寄生虫学）或充分应答（两种治疗失败类型均未出现）。 PCR分析将用于区分治疗失败导致的真正复发和再感染发作（msp 1和msp 2分型）。在治疗前收集的样品的离体药物测试将用于通过测量IC 50来确定药物应答的非临床表型。将对单拷贝恶性疟原虫疫苗候选抗原（msp 1、msp 2和csp）的多态性进行基因分型，以评估MOI，并对与耐药性相关的推定分子标志物进行表征，以确定其频率以及与耐药性表型和MOI的相关性。此外，将每年对每个研究地区的100名学童进行一次横断面调查（200个样本来自两个生态区，800个样本在四年内），以评估人口的感染多重性。我们将检验以下假设：在高疟疾传播强度（森林生态区），耐药寄生虫的流行率随着多克隆感染而降低，在低疟疾传播强度（沿海萨凡纳生态区），耐药寄生虫的流行率随着克隆感染而增加。

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).