On October 10, 1997, the Public Health Inspector from the Departmental Directorate of Health and Social Affairs of the Pyrénées-Atlantiques reported a case of Legionnaires' disease requiring hospitalization. The patient had returned from an organized tour to Turkey, during which another tourist had been urgently repatriated due to pneumonia and had died shortly thereafter. At the same time, another case of Legionnaires’ disease involving a person who had traveled to Turkey the previous month was reported to the National Public Health Network. The following week, several cases of pneumonia were also reported among people who had traveled to Turkey. A cross-check of the hotels visited by the first patients quickly revealed that a single hotel was common to the various tour groups and was likely the site of infection. Sixteen cases of pneumonia were identified among French residents who had stayed at this hotel, the site of the infection. Four people died (aged 69 to 77). This outbreak provides an opportunity to highlight several aspects of the diagnosis and prevention of Legionnaires' disease. (adapted from the text)