Résumé
Background: Salmonella's ability to persist in the environment and its asymptomatic carriage in various species complicates efforts to control it in the field. Farms with diverse livestock activities (such as poultry, cattle and pigs) are common in France. This setup complicates the movement of vehicles, people, and equipment, increasing the risks of cross-contamination. Nevertheless, this issue has received relatively little attention so far. This project deals with this challenge by using a territorial and dynamic approach to the epidemiology of Salmonella, in order to identify effective control measures. Methods: Poultry farms that are recurrently contaminated with Salmonella, and with with diverse livestock activities on the site, are selected to implement this approach. First, potential circulation routes on the site are identified through a comprehensive flow mapping. A longitudinal monitoring is then carried out, involving 120 to 150 environmental samples (collected across 3 to 4 visits at different seasons) to detect Salmonella (serotyping and genotyping). Then, a participatory approach is implemented with farmers, veterinarian and if applicable, neighboring farmers with epidemiological links, to brainstorm together about sanitary barriers, flows organization, and management of risk to reduce the risk of cross-contamination. Results and discussion: A first farm was included in 2024. The site includes a rabbit unit, broiler and duck units, a cattle unit, and 350 ha of crops surrounding it. In November 2023, Salmonella Typhimurium was detected in the rabbitry, severely impacted the rabbit flock, causing abortions). Salmonella Arizonae was detected in the rabbit manure storage pit in April 2024. Salmonella Veneziana was detected in November 2024, inside a cattle stall, while Salmonella Typhimurium was detected on shared equipment with neighboring farmers, and in a nearby pasture. these initial results suggest significant Salmonella environmental contamination. The representation of flows of the site helped to identify potential high-risk areas for cross-contamination during a first workshop with the farmer and veterinarian. Three organizational changes were proposed by the farmer to reduce these risks: relocating the carcass freezer, moving the shared equipment storage area and changing the route for evacuating cattle manure. Ongoing monitoring of this farm will continue to assess whether these changes have a positive impact on reducing environmental contamination. Figure 1: cartography of flows on the case study and identification of potential risk area for cross contamination