A second Dallas health-care worker has tested positive for Ebola, officials said Wednesday, as they also asked 132 people who flew with that infected woman on a Frontier Airlines flight from Cleveland to Dallas on Monday to call the federal Centers for Disease Control. Officials also warned that additional cases of the deadly virus at the Dallas hospital where the woman worked is "a very real possibility." "We have contingencies for more," said Dallas County Judge Clay Jenkins during a briefing on the latest case, of a female employee of Texas Health Presbyterian Hospital who cared for Ebola patient Thomas Eric Duncan. Jenkins said the second infected woman, who was not identified by name or job title, was isolated within 90 minutes of reporting a fever Tuesday. She is the third person diagnosed in the U.S. with Ebola, which is currently epidemic in three West African countries. The CDC hours later revealed that the newly infected woman had flown on Monday on Frontier Airlines Flight No. 1143 from Cleveland to Dallas/Fort Worth. The CDC asked all passengers aboard that flight to call 1-800-232-4632. Frontier Airlines, in its own statement, said passengers who also traveled with the woman on Flight 1142 on Friday from Dallas/Fort Worth to Cleveland should also contact CDC at the same phone number. "Individuals who are determined to be at any potential risk will be actively monitored," the CDC said in a prepared statement. CDC said the woman exhibited no symptoms aboard the flight on Monday evening. Frontier Airlines said Flight 1142 remained overnight from Monday and received a thorough cleaning per normal procedures. It was also cleaned again in Cleveland on Tuesday night, the airline said. Read MoreTexas college bans students from 'Ebola countries'

The woman's employer, Texas Health Presbyterian, is facing renewed criticism for its handling of Duncan's case, which also led to the the infection of nurse Nina Pham, 26, who is also in isolation at the hospital. Texas Health didn't initially admit the Liberian national Duncan for treatment Sept. 25 despite knowing he had a high fever and had recently traveled from West Africa, center of the largest Ebola outbreak on record. Duncan was admitted three days later after becoming more seriously ill. He died Oct. 8.

The newly diagnosed woman was one of 77 people, including Pham, who was involved in treating Duncan or handling his blood. All were placed on monitoring list, but only after Pham was diagnosed with Ebola over the weekend. They join 48 people who had or may have had contact with Duncan before he was admitted to the hospital.



The Texas Health Presbyterian Hospital in Dallas, Texas October 1, 2014. Mike Stone | Reuters

"Health officials have interviewed the latest patient to quickly identify any contacts or potential exposures, and those people will be monitored," the Texas Department of Health said in a statement. "The type of monitoring depends on the nature of their interactions and the potential they were exposed to the virus."

As with Pham's case, it is not known precisely how the second woman became infected while caring for Duncan.

Jenkins called the new case "a gut shot" to the staff at Texas Heath, "because this is one of their own." He said more cases there are "a very real possibility."

Jenkins called the woman in the second case "a heroic person, a person who is dedicating her life to serving others." "And we hope and pray that, like Nina, she will get on a good track."

Read MoreCDC adds 76 to Ebola watchlist, regrets not sending big team

Early Wednesday, officials made reverse 911 calls to neighbors of the newly diagnosed woman. The common areas outside her apartment were cleaned, and the inside of her unit was set to be cleaned later in the day. The woman lives alone, with no pets, officials said. The latest case came to light just hours after federal Centers for Disease Control Director Thomas Frieden said he regretted not having immediately sent a more "robust" CDC team Texas Health after Duncan was admitted with Ebola in late September. Frieden said such a step "might have prevented" Pham's infection. Read MoreEbola: Is the world ready for the next pandemic?

Her diagnosis led the CDC to "rethink" the way it tries to control Ebola from spreading to caregivers, said Frieden, who since has dispatched a specialized infection-control team to Texas to complement an existing CDC squad already in place. Officials are reviewing and revising the protocols for treatment of the two women at the hospital. Frieden, among other things, has suggested that health-care workers may have been using too many layers of protective garb, which can present an opportunity for a mistake when they are removed after interacting with a patient. He also said officials have recommended that fewer care-givers go in and out of the rooms containing an Ebola patient.