Legionnaires’ disease and travel?

Recently we have witnessed an increase in the number of patients diagnosed with legionella in our district. Apart from the known risk factor for legionellosis (smoking, diabetes mellitus, and immunocompromised states) we noticed that 30% of them became ill after flying from or to the country from different areas. The entity of travel-associated legionella is well known but I would like to hear your opinion regarding the possible influence of traveling itself, especially by air, upon the susceptibility of the exposed people to develop disease.

I do not believe that  travel itself, either air or otherwise, plays any direct role in the acquisition of legionnaires’ disease. I believe that the risk factor is the large buildings, e.g., hotels or cruise ships in which the drinking water is colonized with Legionella  to which the traveler is exposed. The solution is not easy since only a small fraction of individuals who stay at these hotels contract Legionnaires’ disease, and that they may also be exposed to drinking water colonized with Legionella from buildings other than hotels. If a significant increase in  travelassociated Legionnaires’ disease is being seen in your district, a study should be performed by your Health Department noting the characteristics of the patients (cigarette smoking is more important than diabetes) and the sources of drinking water to which they were exposed.