A spread sheet created by the U.S. Centers for Disease Control and Prevention to project the trajectory of the West Africa Ebola epidemic shows the potential for the numbers of cases to decline as steeply as they have risen, CDC director Dr. Tom Frieden said today as he introduced the online modelling tool today. It also, he said, shows “the costs of delay are significant.”
In August, before U.S. government responses to the epidemic began to surge, that added up to projections of from more than half a million, to more than a million cases — depending on extents of unreported cases — across Liberia and Sierra Leone by mid-January. (While Ebola continues to threaten public health in Guinea where the epidemic began with 49 reported cases in March, it has had both greater success and more variables, that have led to three waves of outbreaks, Frieden said.) Within minutes of their release this morning, those estimates, in a supplement to the agency’s Morbidity and Mortality Monthly Report were the focus of reporting on the tool and the information it could provide, a focus that Frieden called “unavoidable but unfortunate.” Scenarios leading to those estimates already have changed, he said, with the beginnings of international efforts that last week included President Obama’s announcement of troops, U.S. Public Health Service staff, and supplies to be sent to West Africa, and by the United Nations announcement of an emergency response mission. Important findings from the modelling provided by the spreadsheet include, he said, the daily cost of inadequate action as well as that “a surge now can break the back of the epidemic.”
In addition to spurring action, the spreadsheet will be useful to countries planning their responses to Ebola, said National Security Council Senior Director Gayle Smith, who joined Dr. Frieden. “The value of data in this entire response,” she said, “is this is something we know how to respond to.”
The spreadsheet’s modelling software reaches calculations based on numbers entered of people exposed to, infected with, incubating, infectious, and recovered from Ebola, as well as capacities of Ebola treatment centers and other care settings. The numbers of people counted as infectious, the report released with the spread sheet notes, include those who have died, whose burial continues to pose risks of transmission. While the spreadsheet offers room for numbers of people successfully isolated, it does not quantify other standards of care or outcomes, including deaths. The quality of care can be suggested by the numbers of people who seek care at Ebola treatment centers, Frieden said, and treatment, including rehydration, can cut death rates in half.