Innovative geo-referencing system for epidemiological investigation of Legionella outbreaks in Lombardy Region (Italy)

Cities have become pivotal in health promotion strategies, as the urban environment majorly impacts population’s wellbeing. A proper urban design and the use of appropriate technologies are important in preventing risk factors for infectious disease, such as legionellosis. Legionella pneumophila, a gram-negative bacteria that predominantly affects respiratory tract, is extensively spread in most communities and working environments, health and social care facilities, contaminating water tanks and towers. Early localization of outbreaks and adequate disinfection of water reduce the chances of pathogen transmission. Materials and Methods A retrospective study of all cases of legionellosis that occurred in Lombardy Region during the three-year interval 2018-2020 was carried out. All data were retrieved from the regional Data Warehouse and the Infectious Disease Management On-Line System. The study was carried out in compliance with the "Guidelines for the prevention and control of legionellosis". Results Legionella pneumophila follows a fixed spatio-temporal pattern as it concentrates in urban settings during summer and fall months. Throughout the three-year interval, about 1,000 cases were reported each year, 1,096, 1,051 and 806 respectively, corresponding to an incidence rate of 10.9, 10.5 and 8.0 per 100,000 population. The highest number of cases was recorded by the Local Health Agencies of Milan and Insubria, specifically around the areas of Como and Busto Arsizio. Discussion Lombardy Region is developing a geo-referencing system (GEOSA) with the aim of creating a Geographic Viewer that will report natural and anthropogenic features of different living, collective and working facilities in the territory. This tool is useful for investigating the effects of environmental exposures in urban and suburban settings. The software provides information regarding the environment in which a Legionella outbreak develops, supplying the exact location and contributing to the analysis of the structure from which it may originate.