Sporadic cases of community acquired legionnaires' disease: an ecological study to identify new sources of contamination.

STUDY OBJECTIVE To explore the relation between incidence of sporadic and community acquired legionnaires' disease and exposure to potentially contaminated industrial aerosols. DESIGN Geographical ecological approach using the postcode as the statistical unit. A multivariate Poisson regression model was used to model the relation between exposure to industrial aerosols and legionnaires' disease. SETTING Metropolitan France. MAIN RESULTS More than 1000 sources of industrial exposure (aerosol and plume of smoke) were identified in 42 French departments. After adjusting for confounding factors, there was a statistically increased incidence of legionnaires' disease in postcodes with plume of smoke in comparison with postcodes without (RR=1.45, 95% CI=1.12 to 1.87), and in postcodes with more than one aerosol in comparison with postcodes without (RR=1.37, 95% CI=1.04 to 1.79). CONCLUSION These findings highlight that any industrial systems generating water aerosols should be regarded as potential sources of contamination for legionnaires' disease.