The Italian Multicentric Study on Legionnaires’ disease

The general objective of the Italian Multicentric Study on Legionnaires’ disease is the investigation of some of the critical aspects of this emerging disease, with a specific interest in the Italian situation. An epidemiological study is being conducted in different Italian localities to evaluate the diffusion of Legionella spp in the environment and the efficiency of some of the control strategies to detect cases, study their related risk factors and to establish the frequency of infection within groups at different exposure levels. The first results obtained from the research project are presented below. I T A L I A N J O U R N A L O F P U B L I C H E A L T H were structural, such as to have a centralised and old water distribution system, instead of a more recent one with high copper levels in the water were protective against Legionella contamination. By conducting a large surveillance of pneumonia cases between 2002 and 2003, the study detected 165 cases of legionellosis from 4340 examined patients with a frequency of 3.8% for community acquired case and 5% for nosocomial cases. In the first group of patients recruited for the case-control study, only pre-existing immunopathologies were found to be associated with the disease, whereas smoking habits and co-morbidity were risk factors for all pneumonia. A significant decrease in CD16 (natural killer) cell numbers was found in the affected patients in comparison to the control group. Furthermore, significant alterations in iron metabolism were associated with the disease. We also documented that workers of a contaminated hospital have a higher frequency of antibodies against Legionella spp compared with a control group. However, no subject declared the disease and no association was found between seropositivity and the known risk factors for Legionnaires’ disease. ConclusionsOur active clinical surveillance scheme was ableto detect numerous cases between 2002 and2003, thus contributing to the increase inreported cases from Italy. The rate of infectionamongst pneumonia cases was about 4%,confirming results of other similar surveys. Thepreliminary results of the case-control study showthat cases have peculiar although not sufficientlystudied alterations in both immune andbiochemical parameters.The identification of environmental, immune,genetic and personal risk factors and thequantification of their role in determining theinfection/disease will offer a relevant scientificcontribution, so far scarcely studied by otherresearch programmes.The project is also focusedon the mechanisms of transmission and controlfrom the environment to human subjects, withparticular attention being paid to the risk forcommunities such as hospitals. References1) Borella P,Bargellini A,Pergolizzi S, et al. 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Erratum in : Emerg Infect Dis 2004:10(7):135313) Romano-Spica V, Montagna MT, Stancanelli G, et al. Geneticpolymorphisms as susceptibility factors to Legionellapneumonia.Proceedings of 19th Annual Meeting of the EWGLIGroup 15-18 May 2004 Chamonix Mont Blanc, France (abs).14) Boccia S, Romano-Spica V, Neglia R, et al. Molecular typingof environmental isolates of Legionella pneumophila collectedin Italy over a four years period. 19th Annual Meeting of theEWGLI Group 15-18 May 2004 Chamonix Mont Blanc, France(abs). T h e m e P a p e r s7 7