It's possible, but not very likely.
According to the World Health Organization (WHO), about one-third of the people on Earth are infected by Mycobacterium tuberculosis, the bacteria that causes tuberculosis (TB), although not all of these individuals have or will develop the disease. Many will remain symptom-free, even though they are TB carriers.
Air travel has made it easier for disease-causing bacteria to spread. Since tuberculosis is spread via airborne droplets, usually created through coughing or sneezing, people sitting near a passenger with an active infection might be at risk. However, according to the Centers for Disease Control and Prevention (CDC), you cannot contract tuberculosis by touching items that were used by an infected individual, nor can you get tuberculosis by shaking hands, kissing someone with TB or eating food shared by a person who has TB.
While some airline passengers are pre-screened for tuberculosis, most are not. Typically, airline passengers who are incoming immigrants, students on visas, refugees, military members and families returning from overseas duty, asylum seekers and long-term visitors are screened for tuberculosis prior to their departure date. Most business and leisure travelers do not have to be screened for tuberculosis, and this means that travelers who do not realize they are infected or who know they are infected and travel anyway might spread the bacteria to people sitting near them.
Ideally, travelers who know they are infected should not travel by air until they have been under treatment for the disease for at least two weeks. Practically, however, a situation could arise in which travelers did not know they were infected or knew, did not begin treatment, and flew anyway.
According to the WHO, no cases of transmission of tuberculosis have occurred in situations where the total time passengers spent on board an airplane, including any delays as well as flight time, was less than eight hours. Passenger-to-passenger transmission of tuberculosis has also historically been limited to the area right around the infected passenger, which includes the infected passenger's row, two rows behind and two rows ahead. Risk of infection is lowered if the airplane's ventilation system is activated during ground delays lasting one half hour or longer. Once an airplane is airborne, its HEPA filtration system can trap the bacillus that causes TB, provided that the airplane is equipped with HEPA filters.
The WHO does not identify any increased risk to passengers who travel with a flight crew member who is infected with M. tuberculosis.
In a best-case scenario, an airline will have contact information for each passenger and will be able to cooperate with public health authorities if notification of passengers becomes necessary. In reality, it may be difficult to track down all passengers who might be at risk. The WHO urges public health officials to identify and inform passengers who sat near an infected passenger, whether that passenger was determined to be infected at the time of the flight or became infected within the three-month period preceding the flight.
The Bottom Line
If your doctor tells you that you have infectious tuberculosis and should not fly, stay home. You will put other travelers at risk if you fly before your treatment takes effect.
You can reduce your risk of exposure to infectious tuberculosis by flying on shorter (less than eight hours, including transit time between gates and runways) flights.
Giving accurate, legible contact information to your airline and to customs and immigration officials via the customs and immigration forms you fill out will enable public health authorities to contact you if they determine that you might have been exposed to infectious tuberculosis on your flight. If you are contacted by your airline or by customs officials because you have been exposed to TB, immediately make an appointment with your doctor and insist that you be tested for infectious tuberculosis at an appropriate time.
If you plan to visit an area where infectious tuberculosis is prevalent, discuss your plans with your doctor before your trip. You may wish to have your doctor screen you for infectious tuberculosis eight to ten weeks after you return home.
Centers for Disease Control and Prevention. CDC Health Information for International Travel 2018 ("Yellow Book"). Accessed 27 December 2018. https://wwwnc.cdc.gov/travel/yellowbook/2018/infectious-diseases-related-to-travel/tuberculosis.
Tuberculosis and Air Travel: Guidelines for Prevention and Control. 3rd edition. Geneva: World Health Organization; 2008. 2-3, 7-8. Tuberculosis on aircraft. Accessed 27 December 2018. http://apps.who.int/iris/bitstream/handle/10665/43921/9789241547505_eng.pdf?sequence=1.