DENVER -- You're settling into your tiny coach seat on your next business trip, and the person next to you starts coughing.
In the past, you might have grumbled about him flying with a cold. But now travelers may want to know: Does your seatmate have Ebola?
Probably not. But given the news of the past week, it's hard not to worry.
Affected passengers may not show symptoms for up to 21 days.
Case in point: Thomas Eric Duncan, the first Ebola patient diagnosed in the U.S., was screened for the virus before departing Liberia for the United States on September 19, but he didn't show symptoms until he had been in Dallas for a few days. People who came into contact with him in the United States are being tracked down for monitoring.
Duncan came to the U.S. on United flight 822. The next day that plane, an Airbus A320, traveled to Denver and then onward to other cities, according to FlightAware.com.
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Passengers on those flights are not in danger, said a United spokesperson, noting the CDC advice on symptoms.
"The ill person did not exhibit symptoms of Ebola during the flights from West Africa and CDC does not recommend that people on the same commercial airline flights undergo monitoring, as Ebola is contagious only if the person is experiencing active symptoms," advised the CDC, in a statement.
LINK: Fast facts about Ebola
How can air travelers stay calm?
Travel blogger Johnny "Jet" DiScala, reached on Thursday at 35,000 feet flying from Toronto to Honolulu via Los Angeles, takes a few additional steps to keep calm.
DiScala, who visits 20 countries and flies about 150,000 miles annually, knows how Ebola is transmitted and isn't concerned about catching it. But he refuses to read stories about the disease to avoid panicking.
DiScala also carries surgical masks, which he will wear and offer to travelers "coughing and sneezing on me."
Several airlines report they are following all U.S. Centers for Disease Controls protocols for keeping people with contagious diseases off their aircrafts. But a handful declined to give specifics about whether they're now doing anything differently on U.S. domestic flights.
Airplanes are given light cleanings between flights, a much heavier daily cleaning and even more on down time, experts tell CNN. This is done to prevent transmission of common diseases, like the flu, via surfaces such as armrests. And it is much tougher to catch Ebola than the flu.
In one CDC study, the Ebola virus lived in a perfectly controlled environment for up to six days. But the environment at an airport, for example, is not perfectly suited to support viruses.
It's unlikely the virus would spread on an airplane unless a passenger were to come into contact with a sick person's bodily fluids, said Dr. Marty Cetron, director of CDC's Division of Global Migration and Quarantine.
"This is not an airborne transmission," Cetron told CNN. "There needs to be direct contact frequently with body fluids or blood."
Guidance for travelers
It's no surprise that the U.S. government recommends that travelers avoid areas experiencing outbreaks and avoid contact with Ebola patients.
Most people who have become infected with Ebola lived with or cared for an ill patient, said Stephen Monroe, deputy director of CDC's National Center for Emerging Zoonotic and Infectious Diseases.
"It's very unlikely that they would be able to spread the disease to fellow passengers," he said.
Ebola symptoms include fever, intense weakness, muscle pain, headache and sore throat; followed by vomiting, diarrhea, rash, impaired kidney and liver function, and at advanced stage, both internal and external bleeding, according to the World Health Organization.
"It is highly unlikely that someone suffering such symptoms would feel well enough to travel," the International Air Transport Association said in a statement.
The CDC is advising people to avoid all non-essential travel to Liberia, Guinea or Sierra Leone. In addition, everyone leaving those three countries has their temperature checked before they're allowed to board a plane.
CNN contributed to this report.