Identificazione di potenziali fattori di rischio per i casi di infezione da Salmonella enterica subsp enterica sierotipo Napoli attraverso uno studio caso-controllo nidificato condotto in Regione Lombardia

Enter-net surveillance system has detected the reemergence of Salmonella enterica subsp enterica serotype Napoli (S. Napoli) since 2002. Preliminary data show that food vehicle could not be the only one implicated in the transmission of this serotype. A nested case-control study has been conducted using data form a prospective cohort: for each salmonellosis notification in Lombardia from May 2004 to December 2005 an ad hoc epidemiological investigation has been performed. Cases have been defined as subjects affected by salmonellosis with a positive faecal sample for Salmonella serotype Napoli and controls as subjects affected by salmonellosis with a positive faecal sample for Salmonella serotype not Napoli. Among 2185 salmonellosis notifications collected by 12 of 15 Local Health Authorities, we identified 67 cases and 867 controls. Infection due to S. Napoli were significantly more common among subjects with exposure to surface water (adjusted Odds Ratio (OR)=3,82; 95% Confidence Interval (C.I.)=1,03-14,19), to domestic animals (adjusted OR=3,22; 95% C.I.=1,28-8,10) and among person who practice activities connected to surface water (adjusted OR 3,88; 95% C.I.=1,15-13,05) compared to subjects not exposed to these factors. Hyperendemia of S. Napoli could be attributable to an animal reservoir not yet identified: surface water contamination may be a direct (waterborne infection) or indirect (foodborne infection) vehicle for transmission of S. Napoli behaviour.