Thousands of flights to Mexico were canceled last year in response to the outbreak of the H1N1 virus there. And the SARS scare in 2003 prompted airports and airlines to adopt emergency measures, among them screening passengers for high fevers as they boarded.
No wonder, then, that an aircraft's cabin is commonly seen as a particularly effective purveyor of communicable disease. True, jet travel can spread diseases from one continent to another far faster than in the past. But recent studies, including a report in August by the National Research Council's Transportation Research Board, make a case that, in general, an airplane is no more a health threat to occupants than any other enclosed environment, like a theater or subway.