The United States has issued a travel warning for three African countries hit by the Ebola outbreak.
The World Health Organization says the deadliest Ebola outbreak in history now has killed more than 700 people across West Africa.
According to new figures released Thursday, at least 57 deaths have been reported in recent days.
Nearly half of the new deaths were reported in Liberia.
Liberia's president ordered the nation's schools to close on Wednesday and also demanded that most government employees stay home in a bid to stop the disease's spread.
Sierra Leone, where nine new deaths were reported, also has declared a public health emergency and is trying to quarantine sick people at home who have refused to go to isolation centers.
Ebola cases first emerged in Guinea back in March, though the crisis has dramatically deepened in the last week.