More data needed to accurately predict Ebola’s spread
Above:Air traffic connections from west African countries to the rest of the world. Guinea, Liberia, and Sierra Leone are minimally connected outside of the region; in contrast, Nigeria is well connected and quite populous. Below:Cumulative number of Ebola deaths in Sierra Leone, Guinea, and Liberia as of 1 July 2014. The green line divides the World Health Organization (WHO) data region, used for the model selection, from the projection region. Red dots correspond to official WHO reports. Blue dots are experimental data points received after model calibration. Thin black lines represent expected values. Grey areas correspond to the 95% reference range provided by the fluctuations of the stochastic (randomized) microsimulations.
Recent research published online in PLOS Currents: Outbreaksdetails the early epidemic dynamics of the west African 2014 Ebola outbreak. The epidemic is the largest ever to have occurred, and containment is cause for concern as the latest reports from the World Health Organization (WHO) call into question the number of reported cases. At the beginning of September, the number of cases had topped 4,000 and deaths exceeded 2,000.
The model, created by researchers at the Laboratory for the Modeling of Biological and Socio-technical Systems at Northeastern University in Boston, Massachusetts, US, projects between 6,000 and 10,000 Ebola cases by late September. To create the simulation, the researchers used the Global Epidemic and Mobility Model (GLEAM).
The model takes into account real-world population data, population mobility, and the infection's potential rate of spread in hospitals and communities. Satellite and census data are used to calculate area population densities that are centered on a local transportation hub. Assuming mitigation and control efforts remain unchanged, predictions indicate that in September the disease could reach 10,000 cases. The researchers are careful to note that the model contains assumptions and approximations and that results may change as more data becomes available.
Calling for a scaled-up approach to the outbreak, WHO published a response ‘roadmap’ in August, and was quoted in the Washington Post as saying “that in many areas of intense transmission the actual number of cases may be two to four fold higher than that currently reported." WHO later clarified that "the aggregate case load of [Ebola virus disease victims] could exceed 20,000 over the course of this emergency."
To read the latest WHO situation report, visit the Global Alert and Responsewebsite.
– Amber Harmon
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