CHICAGO (CBS) — A suspected medical problem with a passenger on a Delta Airlines flight from Detroit led emergency crews to quarantine the plane at Midway Airport on Thursday.

It turned out to be a false alarm.

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Passengers were allowed off the plane after about two hours on the tarmac. The passenger who sparked fears about a potentially contagious disease — 50-year-old Lise Sievers of Red Wing, Minn. — had been visiting Africa before changing planes in Detroit. She was released at about 6 p.m.

LISTEN: WBBM Newsradio’s Bob Roberts reports

“Initially everyone was just covering their mouth just to make sure we were not breathing something weird,” one of the stranded travelers, Apeksha Gulvady, told reporters after getting off the plane.

As paramedics examined the woman and took pictures of her mysterious rash to be sent to federal health officials, tension on board grew. One passenger said he looked up potential illnesses from Uganda on Wikipedia.

Sievers told CBS 2’s Roseanne Tellez she is suffering from scabies, which is a rash caused by a small mite.

It can be spread by direct contact with infected people, and less often by sharing clothing or bedding.

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The mites deposit their eggs under the skin. The itchy rash is an allergic response to the mite.

The aircraft, which landed at 3:45 p.m., was identified as Flight 3163 from Detroit. Chicago fire department crews surrounded a Delta airliner near Gate A7 at the airport, according to WBBM Newsradio.

A passenger on the flight, Kayla Maree Sanders, tweeted photos and updates:!/KMaree_Sanders/status/195622832632365056

While crews surrounded the plane, passengers remained on the plane for nearly two hours.!/KMaree_Sanders/status/195643086087532545

The plane was not connected to the gate but sat on the tarmac. Operations continued as normal at the airport, Chopper 780’s Kris Habermehl reported.

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A passenger on the plane, David Grover, told CBS 2 that initially “there was a good amount of panic and disbelief.” Then after nearly two hours, as passengers began to realize their situation wasn’t so serious, that panic turned more into humor.