Application of the EFSA Source Attribution Model (SAM) to compare the main sources of human salmonellosis in Italy related to the national production over the period 2018–2020

Salmonella is one of the leading food-borne pathogens in Europe and is involved in several production chains. Understanding the most common sources of infection is important to address valuable control strategies for this pathogen. In the present study, a Bayesian model, implemented by EFSA, was used to attribute domestic human Salmonella infections, that occurred in Italy over the period 2018–2020, to four putative food animal sources, namely laying hen eggs, broilers, fattening turkeys and pigs and addressing national production. The investigated sources were selected among those most frequently associated with the pathogen. For this purpose, the serotyping data used were previously collected as part of the routine surveillance at primary production (i.e. for poultry) and on carcasses at the slaughterhouse (i.e. for pigs), according to the legislation in place. Model results revealed that in relation to the national production, pigs was the principal food animal source of Salmonella for humans over the period considered, followed by broilers, laying hen eggs, and turkeys. Moreover, for 2020 the estimation of relative risk of acquiring Salmonella by domestic consumption revealed that for pork the relative risk was 3.5 times higher than that from consuming the same amount of eggs, and pork consumption accounted for almost twice the risk of acquiring Salmonella compared to chicken. This result deserves particular attention because, on one hand, it demonstrates the effectiveness of the control measures implemented over the years in poultry at national level, while on the other, it suggests opportunities should be investigated to extend similar control measures to pig populations.