WE DON'T ACTUALLY KNOW HOW MANY EBOLA CASES THERE ARE

We Don't Actually Know How Many Ebola Cases There Are

There's a risk to putting too much stock in the estimates coming out of Ebola-affected countries.

By Sophie Novack

A microscopic view of of the Ebola virus.(Shutterstock)

November 24, 2014 We know the Ebola outbreak in West Africa is really bad. But exactly how bad remains largely a mystery.

There have been 15,351 reported Ebola cases and 5,459 reported deaths, according to the most recent estimates released by the World Health Organization on Nov. 21. The vast majority of these are concentrated in Liberia, Sierra Leone, and Guinea.

But the numbers are ballpark figures, based on reports from the affected countries. While they provide important information about the trajectory of the epidemic and how response efforts are working, officials warn that the totals are likely pretty far off base.

And there's a real danger in relying too heavily on these shifting figures: Prematurely altering response strategy based on some recent positive signs can wipe out progress that has been made in containing the epidemic.

"The numbers we're using for Ebola cases are the best numbers we have from health ministries and Ebola treatment centers working on the ground, but they do go through revisions and often change," said WHO spokesman Daniel Epstein. "We're doing our best to refine the data and get it as accurate as we can, … but there's not always 100 percent accuracy."

The discrepancy between total reported and confirmed cases can be as high as a few thousand. In Liberia, there have been 7,082 reported Ebola cases, according to WHO, only 2,669 of which are confirmed. In Sierra Leone, there have been 6,190 reported cases and 5,152 confirmed, and in Guinea, there have been 2,047 cases and 1,745 confirmed.

Ebola cases can be confirmed only through laboratory tests, which are not available in many regions of West Africa. The numbers reported could include deaths that were incorrectly attributed to Ebola, Epstein said, and totals may be revised downward if the cause of death is confirmed to be something else. However, a more serious problem is the underreporting of cases that actually are Ebola.

WHO officials think there could be thousands more cases that have not been reported.

"In some areas, we think real numbers are two times the numbers reported; in others it may be as high as 2.5 times and others more like 1.5," Margaret Harris, a WHO spokeswoman in Sierra Leone, wrote in an email. "This varies not only by country but by district. For instance, where there are no laboratories and cases are in very remote areas, it stands to reason there are many cases and deaths going unreported."

The misunderstanding and fear surrounding the virus makes underreporting a significant problem. Officials on the ground say many people are remaining at home after becoming sick, afraid of the treatment centers or of the stigma associated with the disease. This can result in the infection of family members and neighbors, continuing the chain of transmission.

"We still have anecdotal information that some communities are denying the fact that there is Ebola," Pieter Desloovere, a WHO spokesman in Liberia, wrote in an email. "In addition, some communities also hide their sick family members at home and do not want to send them to a health facility for treatment out of fear that the person will die. All these cases are not reported and are not part of the statistics."

This can be particularly true in remote areas, where there may be fewer resources and less of a grasp on the extent of the situation.