U.S. President Barack Obama has called West Africa's deadly Ebola outbreak a threat to global security.
Obama announced a major expansion of the U.S. role in trying to halt its spread, including deployment of 3,000 troops to the region.
The announcement on September 16 came the same day the World Health Organization (WHO) warned that the number of West African Ebola cases could begin doubling every three weeks and that the crisis could end up costing nearly $1 billion to contain.
The worst Ebola outbreak since the disease was identified in 1976 has already killed nearly 2,500 people and is threatening to spread elsewhere in Africa.
Joanne Liu, president of Doctors Without Borders, said the global response was falling short and warned that "the window of opportunity to contain this outbreak is closing."