How Many Americans Could Get Ebola? Study Provides Estimates

Ebola virus strain — Researchers isolated this Ebola virus from patient blood samples collected in Mali.

(Image credit: NIAID)

The United States could have had more than a dozen Ebola cases monthly during the height of the epidemic in West Africa last year, and a half dozen cases in treatment simultaneously, according to a new study.

Researchers estimated the potential highest number and lowest number of U.S. Ebola cases, and how many people would need treatment in this country at the same time. The study used data mostly from the fall of 2014, when the rate of new Ebola cases in West Africa was at its highest. The actual number of people in the U.S. who had Ebola in 2014 — who either contracted the disease while working in Africa, or became infected here while treating a sick patient — stands at 10.

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"The aim of our model was to identify how many cases might be being treated at any one time [in the United States] during the outbreak," said study researcher Gabriel Rainisch, an epidemiologist at the Centers for Disease Control and Prevention. The model was requested by policy makers as a way to plan for possible future U.S. Ebola cases, Rainisch said. "Policy makers didn’t want to be in a situation where there was not enough capacity," to treat Ebola patients in the United States, he said.

The researchers assumed that travelers or health care workers with Ebola who didn't know they were infected before they traveled back traveled to the U.S. could infected as few as zero, and as many as two other people here, before or during their hospitalization. In October last year, the United States had its first case of Ebola in a traveler from Liberia, who infected two other health care workers during treatment at a hospital in Dallas. Other U.S. Ebola cases — including a health care worker in New York who did not know he was infected until arriving back in the United States — have not infected any other people.

Since the Dallas cases, "there's been a tremendous effort to train healthcare workers" in treating Ebola patients, and to provide additional support to U.S. hospitals so that they are prepared, Rainisch said. So although it's possible that each U.S. Ebola case could infect an additional two people (which affects the estimate for the highest number of cases), "my feeling is that's unlikely" to occur in the future, Rainisch said. As of January of this year, there were 71 beds in hospitals across the United States that could be used to treat Ebola patients.

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.