Department of Clinical Epidemiology and Applied Biometry, University of Tübingen, Tübingen, Germany.
Numerus Limited, Tübingen, Germany.
PLoS Negl Trop Dis. 2014 Apr 24;8(4):e2810. doi: 10.1371/journal.pntd.0002810. eCollection 2014 Apr.
The elimination of infectious diseases requires reducing transmission below a certain threshold. The Visceral Leishmaniasis (VL) Elimination Initiative in Southeast Asia aims to reduce the annual VL incidence rate below 1 case per 10,000 inhabitants in endemic areas by 2015 via a combination of case management and vector control. Using a previously developed VL transmission model, we investigated transmission thresholds dependent on measures reducing the sand fly density either by killing sand flies (e.g., indoor residual spraying and long-lasting insecticidal nets) or by destroying breeding sites (e.g., environmental management). Model simulations suggest that elimination of VL is possible if the sand fly density can be reduced by 67% through killing sand flies, or if the number of breeding sites can be reduced by more than 79% through measures of environmental management. These results were compared to data from two recent cluster randomised controlled trials conducted in India, Nepal and Bangladesh showing a 72% reduction in sand fly density after indoor residual spraying, a 44% and 25% reduction through the use of long-lasting insecticidal nets and a 42% reduction after environmental management. Based on model predictions, we identified the parameters within the transmission cycle of VL that predominantly determine the prospects of intervention success. We suggest further research to refine model-based predictions into the elimination of VL.
消除传染病需要将传播率降低到一定阈值以下。东南亚内脏利什曼病（VL）消除倡议旨在通过病例管理和病媒控制相结合的方式，到 2015 年将流行地区每年的 VL 发病率降低到每 10000 居民 1 例以下。利用先前开发的 VL 传播模型，我们研究了依赖于降低按蚊密度的措施的传播阈值，这些措施可以通过杀死按蚊（例如室内滞留喷洒和长效杀虫剂蚊帐）或破坏滋生地（例如环境管理）来实现。模型模拟表明，如果通过杀死按蚊将按蚊密度降低 67%，或者通过环境管理措施将滋生地数量减少 79%以上，就有可能消除 VL。这些结果与最近在印度、尼泊尔和孟加拉国进行的两项集群随机对照试验的数据进行了比较，结果表明室内滞留喷洒后按蚊密度降低了 72%，使用长效杀虫剂蚊帐降低了 44%和 25%，环境管理后降低了 42%。根据模型预测，我们确定了 VL 传播周期中决定干预成功前景的主要参数。我们建议进一步研究，将基于模型的预测细化为 VL 的消除。
