Frontier Airlines is contacting about 750 passengers who flew on the same aircraft a Dallas nurse did right before she was diagnosed with Ebola, HNGN has learned.

On Monday Amber Vinson, a nurse who treated the first Ebola patient to die in the U.S., took Frontier Airlines Flight 1143 from Cleveland, Ohio, to Dallas, Texas, with 132 passengers. Vinson tested positive for Ebola at around midnight Tuesday.

Meanwhile, the same aircraft Vinson flew on went on to make five more flights on Tuesday. It wasn't until Wednesday when airline officials learned Vinson rode that same plane while she was exhibiting early symptoms of the deadly virus.

Frontier Airlines is sending emails to about 750 passengers who flew on that aircraft asking them to notify the Centers for Disease Control and Prevention or their local state health officials if they have concerns about exposure, the airline told HNGN late Thursday.

Two pilots and four crew members were also placed on paid leave for 21 days.  

"These steps were taken out of concern for the safety of our customers and employees," the airline said.

The five flights the aircraft was used for are the following, as reported by The Denver Post: Flight 2024 from Dallas to Cleveland; Flight 1104 from Cleveland to Fort Lauderdale; Flight 1105 from Fort Lauderdale to Cleveland; Flight 1101 from Cleveland to Atlanta; and Flight 1100 from Atlanta to Cleveland.

Frontier Airlines did not specify how many passengers were on each flight.

The aircraft in question was taken out of service Wednesday and has since undergone three thorough cleanings. It was then flown the same day to Denver International Airport, with crew only, where workers will replace the seat covers, carpets and air filters.

"Steps such as removing the aircraft from service, removing aircraft seat covers and carpet and replacing environmental filters as well as placing the crew on paid leave were not requested nor mandated by the CDC," the airline said.

The plane was cleaned right after Vinson took the Monday flight and at least once more before news of her diagnosis broke, according to ABC News. It is expected to be back in service in the next few days. 

The CDC has come under fire for allowing Vinson to board a commercial flight when she had a fever of 99.5 degrees. But she was not prevented from traveling because her temperature was below the threshold of 100.4. A fever is one of the symptoms of Ebola, which is currently killing thousands and sickening thousands more in West Africa.