采用青蒿琥酯-咯萘啶对无症状疟原虫携带者进行社区筛查和治疗以降低疟疾疾病负担：建模和模拟分析。

BACKGROUND

Asymptomatic carriers of Plasmodium falciparum serve as a reservoir of parasites for malaria transmission. Identification and treatment of asymptomatic carriers within a region may reduce the parasite reservoir and influence malaria transmission in that area.

METHODS

Using computer simulation, this analysis explored the impact of community screening campaigns (CSC) followed by systematic treatment of P. falciparum asymptomatic carriers (AC) with artemether-lumefantrine (AL) on disease transmission. The model created by Okell et al (originally designed to explore the impact of the introduction of treatment with artemisinin-based combination therapy on malaria endemicity) was modified to represent CSC and treatment of AC with AL, with the addition of malaria vector seasonality. The age grouping, relative distribution of age in a region, and degree of heterogeneity in disease transmission were maintained. The number and frequency of CSC and their relative timing were explored in terms of their effect on malaria incidence. A sensitivity analysis was conducted to determine the factors with the greatest impact on the model predictions.

RESULTS

The simulation showed that the intervention that had the largest effect was performed in an area with high endemicity (entomological inoculation rate, EIR > 200); however, the rate of infection returned to its normal level in the subsequent year, unless the intervention was repeated. In areas with low disease burden (EIR < 10), the reduction was sustained for over three years after a single intervention. Three CSC scheduled in close succession (monthly intervals) at the start of the dry season had the greatest impact on the success of the intervention.

CONCLUSIONS

Community screening and treatment of asymptomatic carriers with AL may reduce malaria transmission significantly. The initial level of disease intensity has the greatest impact on the potential magnitude and duration of malaria reduction. When combined with other interventions (e.g. long-lasting insecticide-treated nets, rapid diagnostic tests, prompt diagnosis and treatment, and, where appropriate, indoor residual spraying) the effect of this intervention can be sustained for many years, and it could become a tool to accelerate the reduction in transmission intensity to pre-elimination levels. Repeated interventions at least every other year may help to prolong the effect. The use of an effective diagnostic tool and a highly effective ACT, such as AL, is also vital. The modelling supports the evaluation of this approach in a prospective clinical trial to reduce the pool of infective vectors for malaria transmission in an area with marked seasonality.

背景

无症状疟原虫携带者是疟疾传播的寄生虫储存库。在一个地区识别和治疗无症状携带者可以减少寄生虫储存库并影响该地区的疟疾传播。

方法

本研究采用计算机模拟方法，探讨了社区筛查（CSC）后用青蒿琥酯- 甲氟喹（AL）对无症状疟原虫携带者（AC）进行系统治疗对疾病传播的影响。本研究使用的模型是由 Okell 等人创建的（最初用于探索引入基于青蒿素的联合疗法治疗对疟疾流行程度的影响），经过修改后可用于代表 CSC 和 AL 治疗 AC，并增加了疟疾媒介季节性。年龄分组、地区内年龄的相对分布和疾病传播的异质性程度保持不变。根据对疟疾发病率的影响，探讨了 CSC 的数量和频率及其相对时间。进行了敏感性分析以确定对模型预测影响最大的因素。

结果

模拟结果表明，干预效果最大的是在高流行地区（昆虫接种率，EIR > 200）进行的；然而，在随后的一年中，感染率又恢复到正常水平，除非再次进行干预。在疾病负担较低的地区（EIR < 10），单次干预后，发病率下降可持续三年以上。在旱季开始时连续进行三次 CSC（每月间隔）对干预的成功具有最大的影响。

结论

用 AL 对无症状携带者进行社区筛查和治疗可能会显著降低疟疾传播。疾病强度的初始水平对疟疾减少的潜在幅度和持续时间影响最大。当与其他干预措施（例如长效杀虫剂处理蚊帐、快速诊断测试、及时诊断和治疗，以及在适当情况下进行室内滞留喷洒）相结合时，这种干预措施的效果可以持续多年，并且它可以成为一种工具，加速将传播强度降低到消除前水平。至少每隔一年进行重复干预可能有助于延长效果。使用有效的诊断工具和高效的 ACT，如 AL，也是至关重要的。该模型支持在具有明显季节性的地区进行前瞻性临床试验，以评估这种方法来减少疟疾传播的感染媒介数量。