NEW YORK (AP) — U.S. health officials are monitoring the Ebola outbreak in Africa but say the risk of the deadly germ spreading to the United States is remote.

The Centers for Disease Control on Monday sent a health alert to U.S. doctors about the outbreak. There are no travel restrictions to the West Africa region hit by the disease. But last month, the CDC issued a mid-level travel advisory for health workers.

Two American aid workers in Liberia have tested positive for the virus and are being treated there. The family of one worker — a doctor — recently returned to the U.S. for a visit. The CDC said they are fine.

Officials stressed people are not contagious until they show symptoms, and the doctor's family left Liberia days before he got sick.