WASHINGTON (AP) — President Barack Obama huddled with some of his senior national security aides and with top administration health officials Monday for the latest assessment on the government’s response to Ebola in the aftermath of a Dallas nurse contracting the disease.

Obama met in the Oval Office with national security adviser Susan Rice, Health and Human Services Secretary Sylvia Burwell and Lisa Monaco, his top aide on homeland security and counterterrorism issues. Tom Frieden, the director of the Centers for Disease Control and Prevention, joined the meeting by phone.

The White House said Obama also wants an update on steps underway to ensure the national health system is prepared to deal with the disease.

The White House has said Obama has asked the Centers for Disease Control and Prevention to move quickly to investigate the infection of the nurse, the first to catch the disease in the United States.

The nurse had treated a Liberian man who died at the hospital after bringing the disease from Liberia.

The meeting came shortly after Frieden urged hospitals to be on greater alert for patients with fever or symptoms of Ebola who have traveled from the three Ebola-stricken African nations of Guinea, Sierra Leone and Liberia in the past 21 days. 

The CDC is now monitoring all hospital workers who treated the Liberian man. Frieden said he wouldn’t be surprised if another hospital worker who cared for that patient when he was very sick becomes ill. 

Obama has tried to maintain a high profile on the Ebola crisis in West Africa, especially since Thomas Eric Duncan fell ill in Texas after traveling from his home in Liberia.

On Sunday, the White House gathered reporters and photographers on the portico outside the Oval Office to observe Obama on the phone with Burwell regarding the Dallas Ebola diagnosis. On Monday, only photographers were permitted into the Oval Office at the beginning on his meeting.