Health officials are closely monitoring a possible second Ebola patient who had close contact with the first person to be diagnosed in the U.S., the director of Dallas County’s health department said Wednesday.

All who have been in close contact with the man diagnosed are being monitored as a precaution, said Zachary Thompson, director of Dallas County Health and Human Services.

“Let me be real frank to the Dallas County residents: The fact that we have one confirmed case, there may be another case that is a close associate with this particular patient,” he said. “So this is real. There should be a concern, but it’s contained to the specific family members and close friends at this moment.”