The United Nations held an emergency session Thursday on the Ebola virus  — which has so far killed nearly 3,000 people in West Africa. U.S. health officials have warned if the outbreak isn't contained soon, the number of people infected could explode to more 1 million by mid-January.

President Barack Obama spoke at the U.N. assembly, and he stressed that Ebola poses a risk to more than just health. He called it a growing threat to regional and global security, adding that epidemic could cause a humanitarian catastrophe across the entire region if the virus isn't stopped.

Dr. Suzanne Donovan knows first-hand how dire the situation is. She is a medical director of Infection Control and an infectious diseases specialist at Olive View UCLA Medical Center. She just returned to the U.S. after a month-long stint in Sierra Leone, where she treated Ebola patients and trained those caring for them.

Staff on the ground is completely overwhelmed, Dr. Donovan said. At one of the Ebola treatment facilities she visited, there were very few nurses left to treat patients.

"Most of the senior staff had died over the past few months, so you had very, very young nurses who had virtually no mentorship in how to approach this outbreak," she said.