Centers for Disease Control: More U.S. Ebola Cases 'Possible'

The director of the Centers for Disease Control and Prevention (CDC) on Sunday said more Ebola cases are possible after a healthcare worker at a Dallas hospital tested positive for the deadly virus.

The female worker, who cared for the first U.S. patient with the disease, began showing symptoms on Friday, Dr. Tom Frieden told reporters on Sunday. As of Sunday morning, the patient only had "mild symptoms," he said, including a "low-grade fever."

The hospital employee, who has not yet been identified, had "extensive contact" with Thomas Duncan, the Ebola patent who died last week from the illness, according to the CDC. Duncan had contracted the disease in Liberia.

"Unfortunately, it is possible that we will see additional cases of Ebola" because of potential breaches in the use of safety gear, Frieden said.