Post-death Transmission of Ebola: Challenges for Inference and Opportunities for Control

TL;DR

This paper analyzes the impact of post-death Ebola transmission on epidemic modeling, highlighting challenges in parameter inference and emphasizing the importance of controlling post-mortem transmission to better manage outbreaks.

Contribution

It demonstrates the identifiability issues in estimating Ebola parameters and shows how accounting for post-death transmission affects epidemic predictions and control strategies.

Findings

Post-death transmission significantly influences Ebola spread.

Early data cannot reliably infer disease parameters due to identifiability issues.

Reducing post-death transmission can substantially control epidemic scope.

Abstract

Multiple epidemiological models have been proposed to predict the spread of Ebola in West Africa. These models include consideration of counter-measures meant to slow and, eventually, stop the spread of the disease. Here, we examine one component of Ebola dynamics that is of growing concern -- the transmission of Ebola from the dead to the living. We do so by applying the toolkit of mathematical epidemiology to analyze the consequences of post-death transmission. We show that underlying disease parameters cannot be inferred with confidence from early-stage incidence data (that is, they are not "identifiable") because different parameter combinations can produce virtually the same epidemic trajectory. Despite this identifiability problem, we find robustly that inferences that don't account for post-death transmission tend to underestimate the basic reproductive number -- thus, given the observed rate of epidemic growth, larger amounts of post-death transmission imply larger reproductive numbers. From a control perspective, we explain how improvements in reducing post-death transmission of Ebola may reduce the overall epidemic spread and scope substantially. Increased attention to the proportion of post-death transmission has the potential to aid both in projecting the course of the epidemic and in evaluating a portfolio of control strategies.