Tourism is a major industry in many European countries and sensitive to health threats. In France and Spain around 77 million and 40 million persons respectively are estimated to visit annually, with similar high numbers reported to visit Italy. The resident population in each of these countries also adds to the high number of tourists each year. The importance of reporting cases of legionnaires' disease in indigenous travellers to EWGLINET is borne out by the fact that Italy and Spain respectively reported that 54% and 40.6% of their clusters included both indigenous and foreign persons. In France only 24% of the clusters were reported to include both French and non-French tourists, with most comprising French nationals only, reflecting the very high number of indigenous travellers in that country. Clusters constituting cases from more than one country would presumably have remained undetected had there been no international reporting and follow up collaborations through the EWGLINET scheme.

The control and prevention of travel associated legionnaires' disease depends on international collaborations and the good will of national authorities to provide the resources and expertise for best public health to be practiced. Once clusters are detected, investigating the environmental source of infection is relatively straightforward since the accommodation site used by the cases is normally the focus point, supported by epidemiological data. The rapid response by the country of infection also results in the majority of hotel-associated clusters comprising less than four cases each. In contrast, non-travel associated legionella outbreaks, ie those that have a source of infection mainly affecting a population within a widespread geographical area may be much more difficult to investigate and control and frequently involve a large number of cases. The French health authorities have recently been confronted with such an outbreak and its control. It is the first time that an industrial cooling tower is implicated in an outbreak in France. The cooling tower of the chemical plant was incriminated as the most likely source of this prolonged common source outbreak. The cleaning and disinfection interventions on the cooling tower may have played a role in continuation of the environment, after closing of the plant, contributing to the prolonged course of the outbreak. However, more than one source of infection has been noted in community outbreaks elsewhere.

Non-travel associated outbreaks may be politically sensitive for the country concerned but require national legislation for control and prevention. Travel associated legionella outbreaks require international actions and to this end all collaborating countries in EWGLINET are committed to the goal of improving health protection for travellers. All parties involved in tourism and international aspects of public health value EWGLINET's unique role in this process.