More than a billion flight passengers annually raise the question for the special situation of infected passengers and the epidemiological significance of air transport. Low ambient pressure (cabin pressure equals the ambient pressure at an altitude of about 2,400 m) and low humidity are relevant physiological factors on board aircraft. In patients with raised temperatures, metabolic rates and oxygen consumption are increased and hypoxia tolerance is decreased. The mechanisms of cabin pressurization and air-conditioning make the possibility of transmission of infections on board almost neglectable except by direct contact in the immediate vicinity of the infected person. Relevant studies are discussed. To minimize the remaining very small risk to prevent harming infected persons, these persons are excluded by international agreements from air travel. Special airline procedures are discussed on the basis of the SARS epidemic as an example. If infectious diseases such as tuberculosis or meningococcal meningitis are diagnosed after a flight, it is very difficult to trace the contact persons because, for example, of data protection. In addition, transport of vectors by commercial air transport and countermeasures are discussed.
