CNN -- The deadliest Ebola outbreak in history has claimed its first American victim.
And now, there are world-wide fears that the virus could be difficult to contain.
Patrick Sawyer was working in Liberia as a government official for the Ministry of Finance. He was planning to travel to Minnesota to celebrate his daughter's birthday next month.
"I had to tell her Daddy is in Heaven now," said Decontee Sawyer. "She said, 'Well, I thought he was in Liberia.'"
She said her husband was visiting his sister in LIberia, who was ill. He had no idea what was awaiting him.
"They didn't know it was Ebola," she said. "They thought she may have malaria, so he was helping. Had he known, he would have definitely taken better precautions."
The World Health Organization said the current outbreak in West Africa has claimed at least 672 lives.
At least 1200 people in Guinea, Sierra Leone and Liberia have been infected.
The virus is spread through contact with a sick person's bodily fluids.
As for the threat of an outbreak in the U.S., officials remain cautiously optimistic.
"In the U.S., you have much better resources," said CNN Chief Medical Correspondent Dr. Sanjay Gupta. "You'd be able to isolate someone, provide whatever supportive therapy in terms of fluids, things like that to a person. So they'd have a much better chance A) of surviving, and B) not turning into an outbreak."
The CDC has issued an alert to U.S. health workers to be on the lookout for any patients who have recently traveled to West Africa. But, what makes it hard is that it takes two to 21 days for an infected person to show symptoms. The CDC is leaving open the possibility of raising the threat level that would discourage all nonessential travel to Guinea, Liberia and Sierra Leone.