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.
U.S. Ebola patient Thomas Eric Duncan arrived in the United States on Sept. 20 and is still in "serious" condition, 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.
While public health officials do not think the U.S. is at risk of seeing a domestic outbreak of Ebola on the scale of West Africa, authorities are still concerned.
Meanwhile, the United Nations warned that Ebola could become airborne and mutate, in a report from The Telegraph.
Anthony Banbury, the UN Secretary General's Special Representative on the disease, said in the article that the longer the Ebola virus exists, the more likely it could mutate and spread via the air, causing an unlikely but possible "nightmare scenario."
The Texas Department of State Health Services has temporarily widened its examination net from 80 to 100 people who may have had even slight contact with the Ebola patient.
"We are working from a list of about 100 potential or possible contacts and will soon have an official contact tracing number that will be lower," Texas Department of State Health Services spokeswoman Carrie Williams said. "The number will drop as we focus in on those whose contact may represent a potential risk of infection."
Earlier, NBC News had cited Dallas County in reporting that about 80 people had come into contact with Duncan or one of his family members before he was hospitalized and diagnosed with the disease on Tuesday.
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The contacts will be investigated and monitored to determine their actual proximity to Duncan and his family in North Dallas.
These investigations are in addition to the 12 to 18 people, including school-age children, who had direct contact with Duncan, Texas Gov. Rick Perry said on Wednesday.
Authorities have not confirmed whether or not Duncan was already showing symptoms of the virus when he or his family in North Dallas came into contact with those people.