This undated photo made available by the Antwerp Institute of Tropical Medicine in Antwerp, Belgium, shows the Ebola virus viewed through an electron microscope. The World Health Organization on Friday, Aug. 8, 2014 declared the Ebola outbreak in West Africa to be an international public health emergency that requires an extraordinary response to stop its spread. (AP Photo/Antwerp Institute of Tropical Medicine)

A look at US response to Ebola crisis

A look at some of the initiatives President Barack Obama is announcing to ramp up the U.S. response to West Africa's Ebola crisis: