Models overestimate Ebola cases

Rate of infection in Liberia seems to plateau, raising questions over the usefulness of models in an outbreak

NATURE  International Weekly Journal of Science                                     Nov. 4, 2014
by Declan Butler

The Ebola outbreak in West Africa has infected at least 13,567 people and killed 4,951, according to figures released on 31 October by the World Health Organization (WHO). Now, in a rare encouraging sign, the number of new cases in Liberia seems to be flattening after months of exponential growth. Scientists say it is too soon to declare that the disease is in retreat: case data are often unreliable, and Ebola can be quick to resurge. But it is clear that mathematical models have failed to accurately project the outbreak’s course.

 The reality of the Ebola outbreak is not reflected by model projections of high case numbers. Daniel Berehulak/NYT/Redux/eyevine

Researchers are now struggling to understand whether reports of empty beds at treatment centres and declining burial numbers are signs that fewer people are developing Ebola, or whether cases and deaths are going unrecorded.....

Epidemiologists normally use mathematical models to estimate the trajectory of an outbreak, and to estimate where and how to direct scarce medical resources. But for the current crisis, on-the-ground data contradict the projections of published models, says Neil Ferguson, an epidemiologist at Imperial College London, and a member of the WHO’s multidisciplinary Ebola Response Team.

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http://www.nature.com/news/models-overestimate-ebola-cases-1.16279