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President Obama on Wednesday praised American health care workers who have volunteered to fight the Ebola epidemic in West Africa, saying, "The world needs you more than ever."

"We need to call them what they are, which is American heroes," he said in a speech from the White House. "They deserve our gratitude and they deserve to be treated with dignity and respect."

Obama also warned that until the outbreak is contained, "we may continue to see individual cases in America."