Data from: Strategies for understanding and reducing the Plasmodium vivax and Plasmodium ovale hypnozoite reservoir in Papua New Guinean children: a randomised placebo-controlled trial and mathematical model

Background: The undetectable hypnozoite reservoir for relapsing Plasmodium vivax and P. ovale malarias presents a major challenge for malaria control and elimination in endemic countries. This study aims to directly determine the contribution of relapses to the burden of P. vivax and P. ovale infection, illness, and transmission in Papua New Guinean children. Methods and Findings: From 17 August 2009 to 20 May 2010, 524 children aged 5–10 y from East Sepik Province in Papua New Guinea (PNG) participated in a randomised double-blind placebo-controlled trial of blood- plus liver-stage drugs (chloroquine [CQ], 3 d; artemether-lumefantrine [AL], 3 d; and primaquine [PQ], 20 d, 10 mg/kg total dose) (261 children) or blood-stage drugs only (CQ, 3 d; AL, 3 d; and placebo [PL], 20 d) (263 children). Participants, study staff, and investigators were blinded to the treatment allocation. Twenty children were excluded during the treatment phase (PQ arm: 14, PL arm: 6), and 504 were followed actively for 9 mo. During the follow-up time, 18 children (PQ arm: 7, PL arm: 11) were lost to follow-up. Main primary and secondary outcome measures were time to first P. vivax infection (by qPCR), time to first clinical episode, force of infection, gametocyte positivity, and time to first P. ovale infection (by PCR). A basic stochastic transmission model was developed to estimate the potential effect of mass drug administration (MDA) for the prevention of recurrent P. vivax infections. Targeting hypnozoites through PQ treatment reduced the risk of having at least one qPCR-detectable P. vivax or P. ovale infection during 8 mo of follow-up (P. vivax: PQ arm 0.63/y versus PL arm 2.62/y, HR = 0.18 [95% CI 0.14, 0.25], p < 0.001; P. ovale: 0.06 versus 0.14, HR = 0.31 [95% CI 0.13, 0.77], p = 0.011) and the risk of having at least one clinical P. vivax episode (HR = 0.25 [95% CI 0.11, 0.61], p = 0.002). PQ also reduced the molecular force of P. vivax blood-stage infection in the first 3 mo of follow-up (PQ arm 1.90/y versus PL arm 7.75/y, incidence rate ratio [IRR] = 0.21 [95% CI 0.15, 0.28], p < 0.001). Children who received PQ were less likely to carry P. vivax gametocytes (IRR = 0.27 [95% CI 0.19, 0.38], p < 0.001). PQ had a comparable effect irrespective of the presence of P. vivax blood-stage infection at the time of treatment (p = 0.14). Modelling revealed that mass screening and treatment with highly sensitive quantitative real-time PCR, or MDA with blood-stage treatment alone, would have only a transient effect on P. vivax transmission levels, while MDA that includes liver-stage treatment is predicted to be a highly effective strategy for P. vivax elimination. The inclusion of a directly observed 20-d treatment regime maximises the efficiency of hypnozoite clearance but limits the generalisability of results to real-world MDA programmes. Conclusions: These results suggest that relapses cause approximately four of every five P. vivax infections and at least three of every five P. ovale infections in PNG children and are important in sustaining transmission. MDA campaigns combining blood- and liver-stage treatment are predicted to be a highly efficacious intervention for reducing P. vivax and P. ovale transmission.

**背景**：引发间日疟原虫（Plasmodium vivax）和卵形疟原虫（Plasmodium ovale）感染复发的、无法被检测到的休眠子（hypnozoite）储存库，给疟疾流行国家的防控与消除工作带来了重大挑战。本研究旨在直接明确复发情况在巴布亚新几内亚儿童的间日疟、卵形疟感染、发病及传播负担中所占的贡献比例。

**方法与结果**：2009年8月17日至2010年5月20日，来自巴布亚新几内亚（PNG）东塞皮克省的524名5~10岁儿童参与了一项随机双盲安慰剂对照试验。受试者被分为两组：261名儿童接受血液+肝阶段治疗药物方案，即氯喹（chloroquine, CQ）给药3天、蒿甲醚-苯芴醇（artemether-lumefantrine, AL）给药3天、伯氨喹（primaquine, PQ）给药20天，总剂量为10mg/kg；另外263名儿童仅接受血液阶段治疗药物方案，即氯喹给药3天、蒿甲醚-苯芴醇给药3天、安慰剂（placebo, PL）给药20天。受试者、研究人员及研究者均对分组分配情况设盲。

治疗阶段共有20名受试者被排除（伯氨喹组14例，安慰剂组6例），剩余504名儿童被主动随访9个月。随访期间，另有18名儿童失访（伯氨喹组7例，安慰剂组11例）。本研究的主要及次要结局指标包括：首次检测到间日疟原虫感染的时间（通过定量聚合酶链反应（quantitative PCR, qPCR）检测）、首次临床发作时间、感染压力、配子体阳性率，以及首次检测到卵形疟原虫感染的时间（通过聚合酶链反应（PCR）检测）。

本研究构建了基础随机传播模型，用以评估大规模药物投放（mass drug administration, MDA）预防间日疟复发感染的潜在效果。通过伯氨喹治疗靶向清除休眠子，可降低受试者在8个月随访期间至少发生1次qPCR检测阳性的间日疟或卵形疟感染的风险（间日疟：伯氨喹组年发生率0.63次，安慰剂组2.62次，风险比（hazard ratio, HR）=0.18，95%置信区间（confidence interval, CI）=0.14~0.25，p<0.001；卵形疟：伯氨喹组0.06次，安慰剂组0.14次，HR=0.31，95%CI=0.13~0.77，p=0.011），同时降低至少发生1次间日疟临床发作的风险（HR=0.25，95%CI=0.11~0.61，p=0.002）。

伯氨喹还可降低受试者随访前3个月内的间日疟原虫血液阶段感染的分子感染压力（伯氨喹组年发生率1.90次，安慰剂组7.75次，发病比率（incidence rate ratio, IRR）=0.21，95%CI=0.15~0.28，p<0.001）。接受伯氨喹治疗的儿童携带间日疟原虫配子体的概率更低（IRR=0.27，95%CI=0.19~0.38，p<0.001）。无论受试者在治疗时是否存在间日疟原虫血液阶段感染，伯氨喹均能发挥相当的治疗效果（p=0.14）。

模型结果显示，采用高灵敏度实时定量PCR进行大规模筛查与治疗，或仅采用血液阶段治疗药物的大规模药物投放，仅会对间日疟的传播水平产生短暂影响；而包含肝阶段治疗药物的大规模药物投放，则被预测为消除间日疟的高效策略。本研究采用的直接督导下的20天给药方案，最大化了休眠子清除效率，但也限制了研究结果向真实世界大规模药物投放项目的外推性。

**结论**：本研究结果表明，在巴布亚新几内亚的儿童中，约五分之四的间日疟感染、至少五分之三的卵形疟感染均由复发引起，且复发是维持疟疾传播的重要因素。联合血液与肝阶段治疗药物的大规模药物投放策略，被预测为降低间日疟与卵形疟传播的高效干预手段。