Exxon Mobil announced on Thursday that it has banned employees to travel to areas most affected by Ebola, as the disease has disrupted its operations in West Africa, including future plans to drill off the shore of Liberia.

Shares of the energy firm fell after the news.

Separately, The Associated Press said Liberia officials will prosecute the man who brought Ebola to the United States for lying on a health form.

Passengers leaving Liberia are being screened for fever and asked if they have had contact with anyone infected. U.S. Ebola patient Thomas Eric Duncan arrived in the United States on Sept. 20 and answered "no" to those questions, a questionnaire obtained by The Associated Press showed.

Neighbors told the wire service that Duncan had helped a sick pregnant woman who later died of the disease. Her illness at the time was believed to be pregnancy-related.

Centers for Disease Control and Prevention Director Tom Friden confirmed Thursday that Duncan did not have any signs of a fever when he was screened at the airport, and did not feel any symptoms until four days after arriving in the United States.



Binyah Kesselly, chairman of the board of directors of the Liberia Airport Authority, told reporters on Thursday that Duncan will be prosecuted when he returns to Liberia.

Under care in a U.S. hospital, Duncan is still in "serious" condition, the Texas Health Presbyterian Hospital said on Thursday.

"The doctors on the medical staff and nurses at Texas Health Presbyterian Hospital Dallas continue to provide compassionate, quality care to the patient who tested positive for Ebola Virus Disease," the hospital said in a statement.

Duncan, a Liberian national, only began showing symptoms of the disease after he arrived in the United States.