Gates Open Res. 2020 Apr 21;3:1553. doi: 10.12688/gatesopenres.13070.2. eCollection 2019.
Gambiense human African trypanosomiasis (gHAT) is a parasitic, vector-borne neglected tropical disease that has historically affected populations across West and Central Africa and can result in death if untreated. Following from the success of recent intervention programmes against gHAT, the World Health Organization (WHO) has defined a 2030 goal of global elimination of transmission (EOT). The key proposed indicator to measure achievement of the goal is zero reported cases. Results of previous mathematical modelling and quantitative analyses are brought together to explore both the implications of the proposed indicator and the feasibility of achieving the WHO goal. Whilst the indicator of zero case reporting is clear and measurable, it is an imperfect proxy for EOT and could arise either before or after EOT is achieved. Lagging reporting of infection and imperfect diagnostic specificity could result in case reporting after EOT, whereas the converse could be true due to underreporting, lack of coverage, and cryptic human and animal reservoirs. At the village-scale, the WHO recommendation of continuing active screening until there are three years of zero cases yields a high probability of local EOT, but extrapolating this result to larger spatial scales is complex. Predictive modelling of gHAT has consistently found that EOT by 2030 is unlikely across key endemic regions if current medical-only strategies are not bolstered by improved coverage, reduced time to detection and/or complementary vector control. Unfortunately, projected costs for strategies expected to meet EOT are high in the short term and strategies that are cost-effective in reducing burden are unlikely to result in EOT by 2030. Future modelling work should aim to provide predictions while taking into account uncertainties in stochastic dynamics and infection reservoirs, as well as assessment of multiple spatial scales, reactive strategies, and measurable proxies of EOT.
布氏冈比亚锥虫所致人类非洲锥虫病（gHAT）是一种由寄生虫引起的、通过媒介传播的被忽视热带病，历史上曾影响西非和中非各地的人群，若不治疗可导致死亡。继近期针对gHAT的干预计划取得成功之后，世界卫生组织（WHO）确定了到2030年全球消除传播（EOT）的目标。提议用于衡量该目标实现情况的关键指标是报告病例数为零。综合以往数学建模和定量分析的结果，以探讨提议指标的影响以及实现WHO目标的可行性。虽然病例报告数为零这一指标清晰且可衡量，但它并非EOT的完美替代指标，可能在EOT实现之前或之后出现。感染报告滞后和诊断特异性不完善可能导致在EOT之后出现病例报告，反之，由于报告不足、覆盖范围不够以及存在隐匿的人类和动物宿主，情况也可能相反。在村庄层面，WHO关于持续进行主动筛查直至连续三年无病例的建议有很高概率实现局部EOT，但将此结果外推至更大空间尺度则较为复杂。gHAT的预测模型一直发现，如果当前仅采用医疗手段的策略不能通过提高覆盖范围、缩短检测时间和/或辅以病媒控制来加强，那么到2030年在主要流行地区不太可能实现EOT。不幸的是，预计在短期内实现EOT的策略成本高昂，而在减轻负担方面具有成本效益的策略到2030年不太可能实现EOT。未来的建模工作应旨在进行预测，同时考虑随机动态和感染宿主中的不确定性，以及对多个空间尺度、应对策略和EOT的可衡量替代指标进行评估。
