The number of Ebola cases in West Africa could swell to 1.4 million by mid-January if the epidemic is not contained and the wide-scale response does not continue, according to new estimates released Tuesday by the U.S. Centers for Disease Control and Prevention (CDC).
The estimate is part of a new modeling tool the CDC created for mapping the response to the Ebola virus, which the World Health Organization (WHO) estimates has infected more than 5,800 people and killed at least 2,800 in the latest outbreak.
The CDC said its modeling tool determined that the number of cases has been “significantly underreported,” by a factor of 2.5. Using data gathered in Sierra Leone and Liberia in August, the agency report projected that Ebola cases could reach 550,000 to 1.4 million in the two countries by Jan. 20, 2015, if the immediate response does not continue — with the caveat that those numbers “do not reflect current condition.”
The CDC did not use the tool to project figures in Guinea because cases there have developed in a way that could not be reliably mapped, the agency said.
In a conference call with reporters Tuesday morning, CDC Director Dr. Tom Frieden stressed that the estimate represented a worst-case scenario and was based on data collected before the response to the virus had seriously ramped up.
“It takes time to both see the data and the trends,” he told reporters. “Obviously we don’t think that will come to pass,” he said in reference to the projection of 1.4 million cases, adding that the most important findings of the model are that “a surge [in containment efforts] now will break the back of the epidemic.”
He said the report showed that if approximately 70 percent of people infected with the virus are isolated in medical facilities or Ebola treatment units, the epidemic will begin to decrease and will eventually end.
“It is possible, and we can be on track to turning it around, but the costs of delay are significant, and that’s why the response that we’re seeing from the U.S. and others is so incredibly important, because every day counts and will make a difference in our ability to control this,” Frieden said.
The report said that once a tipping point is reached, “cases will decline about as rapidly as they had increased. Of note, gains below such a tipping point can also significantly reduce cases.”
The CDC’s mapping tool, which uses Microsoft Excel, will be freely available online for public use.
Separately, the WHO has also projected that Ebola cases may be underreported and said Tuesday that 20,000 more people could be infected by November unless more rigorous control methods are implemented, according to an article published in The New England Journal of Medicine.
"Everyone is certainly working very hard to make sure this is a not the reality that we will be seeing," said Dr. Christopher Dye, the director of strategy at the WHO and a co-author of the article, in a briefing with reports. "I will be surprised if we hit 20,000 by then.”