Background Mass drug administration (MDA) is the cornerstone for the elimination of lymphatic filariasis (LF). The proportion of the population that is never treated (NT) is a crucial determinant of whether this goal is achieved within reasonable time frames. Methods Using 2 individual-based stochastic LF transmission models, we assess the maximum permissible level of NT for which the 1% microfilaremia (mf) prevalence threshold can be achieved (with 90% probability) within 10 years under different scenarios of annual MDA coverage, drug combination and transmission setting. Results For Anopheles-transmission settings, we find that treating 80% of the eligible population annually with ivermectin + albendazole (IA) can achieve the 1% mf prevalence threshold within 10 years of annual treatment when baseline mf prevalence is 10%, as long as NT <10%. Higher proportions of NT are acceptable when more efficacious treatment regimens are used. For Culex-transmission settings with a low (5%) baseline mf prevalence and diethylcarbamazine + albendazole (DA) or ivermectin + diethylcarbamazine + albendazole (IDA) treatment, elimination can be reached if treatment coverage among eligibles is 80% or higher. For 10% baseline mf prevalence, the target can be achieved when the annual coverage is 80% and NT ≤15%. Higher infection prevalence or levels of NT would make achieving the target more difficult. Conclusions The proportion of people never treated in MDA programmes for LF can strongly influence the achievement of elimination and the impact of NT is greater in high transmission areas. This study provides a starting point for further development of criteria for the evaluation of NT.

中文翻译：

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从未治疗的比例如何影响消除淋巴丝虫病的大规模药物管理计划的成功？

背景 大规模给药（MDA）是消除淋巴丝虫病（LF）的基石。从未接受治疗的人口比例（NT）是能否在合理的时间范围内实现这一目标的关键决定因素。方法 使用 2 个基于个体的随机 LF 传播模型，我们评估在不同年度 MDA 覆盖情况下 10 年内可达到 1% 微丝虫血症 (mf) 患病率阈值（概率为 90%）的 NT 最大允许水平，药物组合和传播设置。结果 对于按蚊传播环境，我们发现，当基线 mf 患病率为 10% 时，每年使用伊维菌素 + 阿苯达唑 (IA) 治疗 80% 的符合条件人群，可以在每年治疗的 10 年内达到 1% mf 患病率阈值，只要NT＜10％。当使用更有效的治疗方案时，更高比例的 NT 是可以接受的。对于基线 mf 患病率较低 (5%) 且接受二乙基卡马嗪 + 阿苯达唑 (DA) 或伊维菌素 + 二乙基卡马嗪 + 阿苯达唑 (IDA) 治疗的库蚊传播环境，如果符合条件的治疗覆盖率达到 80% 或更高，则可以实现消除。对于 10% 基线 mf 患病率，当年覆盖率达到 80% 且 NT ≤ 15% 时即可实现目标。较高的感染率或 NT 水平将使实现目标更加困难。结论 从未接受过 LF 的 MDA 计划治疗的人群比例可强烈影响消除的实现，并且 NT 的影响在高传播地区更大。这项研究为进一步制定 NT 评估标准提供了一个起点。