CHICAGO (CBS) — As federal officials stepped up efforts to prevent an outbreak of Ebola in the U.S., Mayor Rahm Emanuel praised local health workers for the steps taken to quickly evaluate two people who became ill on flights to Chicago from West Africa.

WBBM Newsradio Political Editor Craig Dellimore reports the mayor said it’s too early to grade the city’s response after a girl and an adult displayed some symptoms of the disease while flying from Liberia on separate flights to O’Hare International Airport.

However, he said the screening process in place at O’Hare and the city’s public health network appeared to handle the patients and their families the right way.

“They are identified on a plane, they were transported from a plane to a hospital, from the hospital to another hospital. That piece of every step, when you compare Dallas to this – the time used to learn what Dallas did wrong, and improve – it looks at this point quite effective,” the mayor said.

Two health workers in Dallas tested positive for Ebola after treating a patient who later died from the disease. That patient, Eric Duncan, showed no signs of Ebola when he arrived from Liberia last month, and was sent home from the hospital a few days later after developing a fever, headache, and abdominal pain.

On Wednesday, the U.S. Centers for Disease Control and Prevention said every passenger traveling to the U.S. from Ebola-stricken nations in West Africa would be monitored for symptoms for three weeks upon their arrival in America.

The effort was scheduled to begin Monday in New York, Pennsylvania, Maryland, Virginia, New Jersey, and Georgia – six states which account for 70 percent of people who fly to the U.S. from Liberia, Sierra Leone, and New Guinea.

CDC Director Tom Frieden said the monitoring eventually will extend to other states, to ensure every such traveler is monitored until the West Africa outbreak is controlled.

Local and state officials will perform the daily monitoring, which may consist of keeping up with people by phone or visits. Individuals arriving from West Africa will receive “care kits” that include thermometers, detailed information on how take their temperature twice a day, and logs for recording the information. Temperatures must be reported to health officials at least once per day.

Frieden said the message to travelers is: “If you become sick, get care quickly because that could save your life and protect your family.”

The kits also will include information on whom to call if symptoms occur and a card the traveler can present to health care providers if they seek care.

Meantime, medical personnel in Chicago said they are using “an abundance of caution” for two patients being evaluated for Ebola, even though neither has been diagnosed with the disease, after each of them became sick on separate flights from Liberia to O’Hare.

Neither patient – a girl and an adult who are not related – has a fever, and neither has been tested for Ebola, but both are being monitored at local hospitals but are no longer in isolation. Both patients showed improvement Wednesday, according to the city health officials.

The girl began vomiting after boarding a flight from Liberia to Chicago, and was taken to Lurie Children’s Hospital after arriving in Chicago, to undergo stringent infection control protocols. The girl later was taken to Comer Children’s Hospital at the University of Chicago, where she was in isolation Wednesday morning. Her family has shown no signs of Ebola.

The girl had no fever, and no known risk of exposure to Ebola. The U.S. Centers for Disease Control and Prevention have decided to test her for Ebola out of an abundance of caution.

Dr. Stephen Weber, chief medical officer at University of Chicago Medicine, said the rigorous protocols were necessary, even though the chances are slim the girl has contracted Ebola.

“It’s important to stress that, at this time, we don’t have a diagnosis of Ebola for this patient. We are being very cautious,” he said. “It may turn out to be very unlikely that that’s what’s affecting this patient.”

In the other case, an adult passenger traveling alone from Liberia reported nausea and diarrhea, but had a normal temperature. That person was being monitored at Rush University Medical Center, but was not tested for Ebola. The patient was diagnosed with typhoid fever in August.

Even though neither patient has been diagnosed with Ebola, doctors and nurses treating them have been wearing appropriate protective gear, going above and beyond CDC recommendations.

“I think abundance of caution is exactly the right words,” Weber said. “Again, the experience of the last couple of weeks have shown that this is a complicated, potentially severe disease. So even the possibility of it – even when it’s remote – warrants specific attention, and great care by expert providers.”