Lewnard Joseph A, Ndeffo Mbah Martial L, Alfaro-Murillo Jorge A, Altice Frederick L, Bawo Luke, Nyenswah Tolbert G, Galvani Alison P
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA; Center for Infectious Disease Modeling and Analysis, Yale School of Public Health, New Haven, CT, USA.
Department of Epidemiology of Microbial Diseases, Yale School of Public Health, New Haven, CT, USA; Infectious Diseases Section, Yale University School of Medicine, New Haven, CT, USA.
Lancet Infect Dis. 2014 Dec;14(12):1189-95. doi: 10.1016/S1473-3099(14)70995-8. Epub 2014 Oct 23.
A substantial scale-up in public health response is needed to control the unprecedented Ebola virus disease (EVD) epidemic in west Africa. Current international commitments seek to expand intervention capacity in three areas: new EVD treatment centres, case ascertainment through contact tracing, and household protective kit allocation. We aimed to assess how these interventions could be applied individually and in combination to avert future EVD cases and deaths.
We developed a transmission model of Ebola virus that we fitted to reported EVD cases and deaths in Montserrado County, Liberia. We used this model to assess the effectiveness of expanding EVD treatment centres, increasing case ascertainment, and allocating protective kits for controlling the outbreak in Montserrado. We varied the efficacy of protective kits from 10% to 50%. We compared intervention initiation on Oct 15, 2014, Oct 31, 2014, and Nov 15, 2014. The status quo intervention was defined in terms of case ascertainment and capacity of EVD treatment centres on Sept 23, 2014, and all behaviour and contact patterns relevant to transmission as they were occurring at that time. The primary outcome measure was the expected number of cases averted by Dec 15, 2014.
We estimated the basic reproductive number for EVD in Montserrado to be 2·49 (95% CI 2·38-2·60). We expect that allocating 4800 additional beds at EVD treatment centres and increasing case ascertainment five-fold in November, 2014, can avert 77 312 (95% CI 68 400-85 870) cases of EVD relative to the status quo by Dec 15, 2014. Complementing these measures with protective kit allocation raises the expectation as high as 97 940 (90 096-105 606) EVD cases. If deployed by Oct 15, 2014, equivalent interventions would have been expected to avert 137 432 (129 736-145 874) cases of EVD. If delayed to Nov 15, 2014, we expect the interventions will at best avert 53 957 (46 963-60 490) EVD cases.
The number of beds at EVD treatment centres needed to effectively control EVD in Montserrado substantially exceeds the 1700 pledged by the USA to west Africa. Accelerated case ascertainment is needed to maximise effectiveness of expanding the capacity of EVD treatment centres. Distributing protective kits can further augment prevention of EVD, but it is not an adequate stand-alone measure for controlling the outbreak. Our findings highlight the rapidly closing window of opportunity for controlling the outbreak and averting a catastrophic toll of EVD cases and deaths.
US National Institutes of Health.
需要大规模扩大公共卫生应对措施，以控制西非前所未有的埃博拉病毒病（EVD）疫情。当前的国际承诺旨在扩大三个领域的干预能力：新建埃博拉病毒病治疗中心、通过接触者追踪确定病例以及分发家庭防护包。我们旨在评估这些干预措施单独应用及联合应用时如何避免未来的埃博拉病毒病病例和死亡。
我们建立了一个埃博拉病毒传播模型，并将其与利比里亚蒙特塞拉多县报告的埃博拉病毒病病例和死亡情况进行拟合。我们使用该模型评估扩大埃博拉病毒病治疗中心、增加病例确定以及分发防护包对控制蒙特塞拉多疫情的有效性。我们将防护包的功效设定在10%至50%之间变化。我们比较了分别于2014年10月15日、2014年10月31日和2014年11月15日启动干预措施的情况。现状干预措施是根据2014年9月23日埃博拉病毒病治疗中心的病例确定情况和能力，以及当时发生的与传播相关的所有行为和接触模式来定义的。主要结局指标是预计到2014年12月15日可避免的病例数。
我们估计蒙特塞拉多埃博拉病毒病的基本繁殖数为2.49（95%置信区间2.38 - 2.60）。我们预计，相对于现状，在埃博拉病毒病治疗中心额外增加4800张床位，并在2014年11月将病例确定能力提高五倍，到2014年12月15日可避免77312例（95%置信区间68400 - 85870）埃博拉病毒病病例。通过分发防护包来补充这些措施可使预计避免的病例数高达97940例（90096 - 105606）。如果在2014年10月15日部署，同等干预措施预计可避免137432例（129736 - 145874）埃博拉病毒病病例。如果推迟到2014年11月15日，我们预计这些干预措施最多可避免53957例（46963 - 60490）埃博拉病毒病病例。
在蒙特塞拉多有效控制埃博拉病毒病所需的埃博拉病毒病治疗中心床位数大大超过美国向西非承诺的1700张。需要加快病例确定，以最大限度地提高扩大埃博拉病毒病治疗中心能力的有效性。分发防护包可进一步增强对埃博拉病毒病的预防，但它不是控制疫情的充分独立措施。我们的研究结果凸显了控制疫情并避免埃博拉病毒病病例和死亡造成灾难性后果的机会之窗正在迅速关闭。
美国国立卫生研究院。
