By Elise Viebeck - 11/17/14 01:29 PM EST
Centers for Disease Control and Prevention (CDC) Director Thomas Frieden said the Ebola epidemic is "nowhere near over" in West Africa, despite a decline in cases in Liberia, one of the hardest-hit countries.
Speaking at an event at the Aspen Institute on Monday, Frieden compared the epidemic to a widening forest fire that could easily spread to other regions in Africa. He said he was "very concerned" by the idea that Ebola is receding, which has been promoted by some media outlets.
Frieden repeated several times, "We have a long way to go" while discussing the CDC's response on the ground and in the United States.
The World Health Organization announced last week that the Ebola death toll now exceeds 5,000, a number that likely underestimates the true number of fatalities.
Reports indicated that some new cases are due to a surge of the disease in Freetown, Sierra Leone. Mali also has a new cluster of cases that is concerning to global health officials.
Ebola was back in U.S. headlines Monday, when an American surgeon died of the virus after being transported from Sierra Leone to Omaha, Neb., for treatment.
The surgeon, Martin Salia of Maryland, initially tested negative for the disease. He arrived at the Nebraska Medical Center in critical condition over the weekend.