Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, 4051, Basel, Switzerland.
University of Basel, Petersplatz 1, Basel, Switzerland.
Malar J. 2019 Jul 30;18(1):259. doi: 10.1186/s12936-019-2893-9.
As areas move closer to malaria elimination, a combination of limited resources and increasing heterogeneity in case distribution and transmission favour a shift to targeted reactive interventions. Reactive case detection (RCD), the following up of additional individuals surrounding an index case, has the potential to target transmission pockets and identify asymptomatic cases in them. Current RCD implementation strategies vary, and it is unclear which are most effective in achieving elimination.
OpenMalaria, an established individual-based stochastic model, was used to simulate RCD in a Zambia-like setting. The capacity to follow up index cases, the search radius, the initial transmission and the case management coverage were varied. Suitable settings were identified and probabilities of elimination and time to elimination estimated. The value of routinely collected prevalence and incidence data for predicting the success of RCD was assessed.
The results indicate that RCD with the aim of transmission interruption is only appropriate in settings where initial transmission is very low (annual entomological inoculation rate (EIR) 1-2 or prevalence approx. < 7-19% depending on case management levels). Every index case needs to be followed up, up to a maximum case-incidence threshold which defines the suitability threshold of settings for elimination using RCD. Increasing the search radius around index cases is always beneficial.
RCD is highly resource intensive, requiring testing and treating of 400-500 people every week for 5-10 years for a reasonable chance of elimination in a Zambia-like setting.
随着各地区逐渐接近消除疟疾的目标，有限的资源以及病例分布和传播的异质性不断增加，促使人们转而采用有针对性的反应性干预措施。反应性病例检测（RCD）是指对索引病例周围的其他人员进行额外追踪，该方法具有靶向传播点并识别其中无症状病例的潜力。目前，RCD 的实施策略各不相同，尚不清楚哪种策略最能有效实现消除疟疾的目标。
采用一种成熟的基于个体的随机模型——OpenMalaria 来模拟赞比亚类似环境中的 RCD。本研究对索引病例的追踪能力、搜索半径、初始传播率以及病例管理覆盖率进行了调整。确定了合适的环境，并估计了消除的概率和达到消除的时间。还评估了常规收集的患病率和发病率数据对 RCD 成功预测的价值。
结果表明，以阻断传播为目的的 RCD 仅适用于初始传播率非常低的环境（每年的媒介感染率（EIR）为 1-2，或在不同的病例管理水平下，患病率约为 7-19%）。需要对每个索引病例进行追踪，直至达到最大病例发生率阈值，该阈值定义了通过 RCD 实现消除的设置适宜阈值。增加索引病例周围的搜索半径总是有益的。
RCD 非常耗费资源，需要每周对 400-500 人进行检测和治疗，持续 5-10 年，才能在类似赞比亚的环境中获得合理的消除机会。
