Transmission of communicable diseases on aircraft
Research has shown that there is very little risk of any communicable disease being transmitted on board an aircraft.
The quality of aircraft cabin air is carefully controlled. Ventilation rates provide a total change of air 20–30 times per hour. Most modern aircraft have recirculation systems, which recycle up to 50% of cabin air. The recirculated air is usually passed through HEPA (high-efficiency particulate air) filters, of the type used in hospital operating theatres and intensive care units, which trap dust particles, bacteria, fungi and viruses.
Transmission of infection may occur between passengers who are seated in the same area of an aircraft, usually as a result of the infected individual coughing or sneezing or by touch (direct contact or contact with the same parts of the aircraft cabin and furnishings that other passengers touch). This is no different from any other situation in which people are close to each other, such as on a train or bus or in a theatre. Highly contagious conditions, such as influenza, are more likely to be spread to other passengers in situations where the aircraft ventilation system is not operating. An auxiliary power unit is normally used to provide ventilation when the aircraft is on the ground, before the main engines are started, but occasionally this is not operated for environmental (noise) or technical reasons. In such cases, when associated with a prolonged delay, passengers may be temporarily disembarked.
Transmission of tuberculosis (TB) on board commercial aircraft during long-haul flights was reported during the 1980s, but no case of active TB disease resulting from exposure on board has been identified subsequently. Nevertheless, increasing air travel and the emergence of drug-resistant TB require continuing vigilance to avoid the spread of infection during air travel. Further information on TB and air travel may be found in the 2008 edition of the WHO publication Tuberculosis and air travel: guidelines for prevention and control.
During the outbreak of severe acute respiratory syndrome (SARS) in 2003, the risk of transmission of the disease in aircraft was found to be very low.
To minimize the risk of passing on infections, travellers who are unwell, particularly if they have a fever, should delay their journey until they have recovered. Individuals with a known active communicable disease should not travel by air. Airlines may deny boarding to passengers who appear to be infected with a communicable disease.