Health officials are still looking for 15 passengers who were on a flight in which a bat flew inside the airplane's cabin so they can protect them against the possibility of rabies.

Danielle Buttke of the Centers for Disease Control and Prevention said Saturday they have contacted 35 of the 50 passengers on the Aug. 5 Delta Air Lines flight 5121 that was operated by Atlantic Southeast Airlines.

She says none of the passengers they've spoken with required treatment.

The plane was flying from Madison, Wisconsin, to Atlanta when the bat emerged. No one knows if the bat had rabies because it escaped.

The CDC wants to talk to the plane's passengers to make sure they didn't have close contact with it, putting them at risk.