EbolaRMS develops probabilistic model of West African Ebola outbreak

Published 24 October 2014

Current outbreak has the potential to be the deadliest infectious disease event since the 1918 flu pandemic. The outbreak will worsen and could reach as many as 1,400 new cases per day within a month, according to pandemic risk experts. According to a new model developed by RMS, until a tipping point is reached at which the number of new daily cases declines rather than increases, the severity of the outbreak will continue to multiply, with the total number of new cases approximately doubling each month.

According to a new report by RMS, a catastrophe risk management firm, the Ebola virus disease outbreak in West Africa has the potential to be the most deadly infectious disease event since the 1918 flu pandemic.

The current outbreak will continue to worsen while the deployment of resources is ramped up to meet the caseload. According to RMS modeling, until a tipping point is reached at which the number of new daily cases declines rather than increases, the severity of the outbreak will continue to multiply, with the total number of new cases approximately doubling each month.

“Controlling the spread of this Ebola outbreak is more a question of logistics than virology,” said Dominic Smith, pandemic risk expert and senior manager of Life Risks at RMS. “The fight against the Ebola epidemic is a race against a moving target; more resources are required as the number of cases increases.”

RMS modeling suggests that, based on current response efforts, the tipping point will not be reached until January 2015. Modeling further reveals a 55 percent chance that by the end of November, at least 1,000 new cases of Ebola will develop daily, and as many as 1,400 per day in a worst-case scenario. There have been more than 9,000 cases reported in total to date.

Adding to the devastation of the Ebola outbreak, overwhelmed medical systems in West Africa have fewer resources to respond to other diseases and the mortality rate of malaria and yellow fever is on the rise. Malaria deaths are likely to continue rising as the seasonal height of malaria transmission is reached next month.

RMS modeled the future paths of cases and deaths from the Ebola virus in Sierra Leone, Guinea, and Liberia, which were combined with a probabilistic assessment of various international medical and military response scenarios to estimate the timing of the tipping point where cases are controlled such that the disease tapers off.

Reaching the tipping point
If effective resources are deployed at a rate that outstrips the pace of increase in new cases, a tipping point can be reached where the number of new daily cases reaches a maximum, allowing response measures to kick in and prevent new infections at a rate that causes the epidemic to subside.