Hochschule Mittweida, University of Applied Sciences Mittweida, Mittweida, Germany.
African Institute for Mathematical Sciences (AIMS), Limbe, Cameroon.
PLoS One. 2023 Jan 17;18(1):e0276351. doi: 10.1371/journal.pone.0276351. eCollection 2023.
The recent outbreaks of Ebola virus disease (EVD) in Uganda and the Marburg virus disease (MVD) in Ghana reflect a persisting threat of Filoviridae to the global health community. Characteristic of Filoviridae are not just their high case fatality rates, but also that corpses are highly contagious and prone to cause infections in the absence of appropriate precautions. Vaccines against the most virulent Ebolavirus species, the Zaire ebolavirus (ZEBOV) are approved. However, there exists no approved vaccine or treatment against the Sudan ebolavirus (SUDV) which causes the current outbreak of EVD. Hence, the control of the outbreak relies on case isolation, safe funeral practices, and contact tracing. So far, the effectiveness of these control measures was studied only separately by epidemiological models, while the impact of their interaction is unclear.
To sustain decision making in public health-emergency management, we introduce a predictive model to study the interaction of case isolation, safe funeral practices, and contact tracing. The model is a complex extension of an SEIR-type model, and serves as an epidemic preparedness tool. The model considers different phases of the EVD infections, the possibility of infections being treated in isolation (if appropriately diagnosed), in hospital (if not properly diagnosed), or at home (if the infected do not present to hospital for whatever reason). It is assumed that the corpses of those who died in isolation are buried with proper safety measures, while those who die outside isolation might be buried unsafely, such that transmission can occur during the funeral. Furthermore, the contacts of individuals in isolation will be traced. Based on parameter estimates from the scientific literature, the model suggests that proper diagnosis and hence isolation of cases has the highest impact in reducing the size of the outbreak. However, the combination of case isolation and safe funeral practices alone are insufficient to fully contain the epidemic under plausible parameters. This changes if these measures are combined with contact tracing. In addition, shortening the time to successfully trace back contacts contribute substantially to contain the outbreak.
In the absence of an approved vaccine and treatment, EVD management by proper and fast diagnostics in combination with epidemic awareness are fundamental. Awareness will particularly facilitate contact tracing and safe funeral practices. Moreover, proper and fast diagnostics are a major determinant of case isolation. The model introduced here is not just applicable to EVD, but also to other viral hemorrhagic fevers such as the MVD or the Lassa fever.
乌干达最近爆发的埃博拉病毒病（EVD）和加纳的马尔堡病毒病（MVD）反映出丝状病毒科对全球卫生界的持续威胁。丝状病毒科的特点不仅在于其高病死率，还在于尸体具有高度传染性，并且在没有适当预防措施的情况下容易引起感染。针对最具毒力的埃博拉病毒种，即扎伊尔埃博拉病毒（ZEBOV），已经批准了疫苗。然而，目前还没有针对导致当前 EVD 爆发的苏丹埃博拉病毒（SUDV）的批准疫苗或治疗方法。因此，疫情的控制依赖于病例隔离、安全的葬礼实践和接触者追踪。到目前为止，这些控制措施的有效性仅通过流行病学模型分别进行了研究，而它们相互作用的影响尚不清楚。
为了在公共卫生应急管理中维持决策，我们引入了一个预测模型来研究病例隔离、安全葬礼实践和接触者追踪的相互作用。该模型是 SEIR 型模型的复杂扩展，是一种流行准备工具。该模型考虑了 EVD 感染的不同阶段，以及对感染进行隔离治疗的可能性（如果得到适当诊断）、在医院治疗（如果未得到适当诊断）或在家中治疗（如果感染者出于任何原因未前往医院）。假设隔离死亡者的尸体被安全埋葬，而那些在隔离之外死亡的人可能不安全地埋葬，从而在葬礼期间可能发生传播。此外，还会追踪隔离个体的接触者。基于科学文献中的参数估计，该模型表明，适当诊断和因此病例隔离对减少疫情规模的影响最大。然而，在合理的参数下，仅单独实施病例隔离和安全葬礼实践不足以完全控制疫情。如果将这些措施与接触者追踪相结合，则情况会发生变化。此外，缩短成功追踪接触者的时间将大大有助于控制疫情。
在没有批准的疫苗和治疗方法的情况下，通过适当和快速的诊断以及流行意识进行 EVD 管理是基础。意识将特别有助于接触者追踪和安全葬礼实践。此外，适当和快速的诊断是病例隔离的主要决定因素。本文引入的模型不仅适用于 EVD，也适用于其他病毒性出血热，如马尔堡病毒病或拉沙热。
