When Thomas Eric Duncan was diagnosed with Ebola two weeks ago, authorities said not to worry — he had no symptoms during his flights from Liberia to Dallas. They said the disease could be spread only by someone who was showing signs such as fever and only through bodily fluids such as vomit. They told passengers who rode with Duncan they couldn’t catch it because it isn’t transmitted through the air.

And, they said, if a passenger is sick or has a fever, the person won’t fly.

Now the Centers for Disease Control and Prevention is busy tracking 132 passengers who traveled this week on a Frontier Airlines flight with Amber Vinson, the second health-care worker who tested positive for Ebola after caring for Duncan, who died earlier this month. On Monday, the nurse went from Cleveland back to Dallas with a low-grade fever. And the next day, the plane took five more trips before Frontier Airlines was notified late Tuesday about Vinson.

CDC Director Tom Frieden said she did not have nausea or vomit on the plane, so the risk to anyone around her is “extremely low.”

Still, many are now concerned about exposure. A flight crew is on paid leave. Several schools in Ohio and Texas have shut down. Students who were on the flight have been asked to stay home. At least one person has put himself in isolation.

Ever since Duncan set foot on American soil on Sept. 20, medical personnel seemed to take one misstep after the other. And the latest may have been the decision to let Vinson fly. Officials said she was running a fever of 99.5 degrees — below the 100.4-degree mark outlined in CDC screening guidelines. Still, Frieden said Wednesday that Vinson should not have been permitted to go anywhere given her risk of exposure.

That fact prompted precautions around the country.

“It seems like it’s not that big of a risk, but it’s pretty scary,” a Frontier union official, who asked to remain anonymous because he was not authorized to speak for the group, told the Los Angeles Times.

The union, which represents some 60,000 flight attendants, called on the CDC to monitor the crew that traveled with Vinson. Frontier Airlines chief executive David Siegel said in a letter that two pilots and four flight attendants have been put on paid leave for 21 days “out of an abundance of caution.”

“These extraordinary actions went beyond CDC recommendations,” the e-mail states. “These steps were taken out of concern for the safety of our customers and employees. 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.”

These concerns seem to be shared by Frontier passengers as well.

In Solon, Ohio, 20 miles southeast of Cleveland, two schools will shut down Thursday so health officials can disinfect the buildings. The school district stated in an e-mail that it made the call after learning that a local middle-school staff member may have been on the same plane — but not the same flight — as Vinson.

Some 1,200 miles away in Belton, Tex., about an hour north of Austin, a school district came to the same conclusion. The school district announced via Twitter that three of its schools would be closed Thursday. And two children who were on the same Frontier flight have been asked to stay home from school for 21 days and monitor their temperatures.

The elementary school student and middle school student went to school Tuesday and Wednesday but were not showing symptoms of the disease. “Because of this, there is no imminent risk to your child,” school officials said in letters sent home to parents. Belton Superintendent Susan Kincannon said during a news conference that both students are considered low risk, but “we anticipate that some parents will choose to keep their children at home.”

And a student in the Eagle Mountain-Saginaw school district — in a county bordering Dallas — will be isolated with family members for three weeks after the shared flight.

A relative of Vinson reportedly quarantined himself after spending time with her in Ohio.

“There are no symptoms with anybody,” Tallmadge Mayor David Kline told 19 Action News. “No Ebola in Summit County, and we have to rest assured in that.”

Still, public health officials are monitoring everyone who came in contact with Vinson.

“Looking at two times a day temperature checks, checking for symptoms. Looking for isolation if anyone develops symptoms,” Margo Erme, county medical director, told the station.

Officials said these actions are not medical recommendations, merely precautions. Even the Dallas hospital at the epicenter offered some “peace of mind and comfort.”

Texas Health Presbyterian Dallas released a statement Wednesday night offering its employees who are concerned about Ebola exposure a place to stay.

“Texas Health Dallas is offering a room to any of our impacted employees who would like to stay here to avoid even the remote possibility of any potential exposure to family, friends and the broader public,” the hospital said. “We will make available to our employees who treated Mr. Duncan a room in a separate part of the hospital throughout their monitoring period.”