American infected with Ebola tries experimental serum

For just the third time, ever, the Centers for Disease Control and Prevention has raised the travel alert to level three, warning against non-essential travel to Liberia, Guinea and Sierra Leone.

The Ebola death toll passed 700 on Thursday, 1,300 people have contracted the virus and it's not showing any signs of slowing down.

Among the sick are two Americans who may come home.

U.S. officials are in on-going talks about getting the Americans out of West Africa, and one of them may have just given up his only chance of survival to save the other.

CNN's Pamela brown reports.