An international investigation of an outbreak of Legionnaires disease among UK and French tourists.

Five cases of legionnaires disease and one death were associated with four members of a tour group from the United Kingdom (UK) and one French tourist who all visited Spain in the spring of 1993. The UK group stayed at four hotels, one of which was also used by the French tourist. Phenotypic and genotypic comparison of isolates of Legionella pneumophila obtained from one of the UK cases and the French patient demonstrated that they were indistinguishable from each other and from environmental isolates obtained from the water supply of the hotel at which all five cases had stayed. A cohort study of the UK tour group was carried out to determine the extent of the outbreak and showed that three further members of the group had respiratory illness but were serologically negative to legionella infection. International participation in this investigation has highlighted the value of a European surveillance scheme and the benefit of microbiological collaboration between legionella reference laboratories in Europe.