Attribution of human cases of salmonellosis to different animal reservoirs of the food chain in Denmark

In recent history, Salmonella has been the second most common cause of bacterial foodborne infections in Denmark, with 1,136 cases reported in 2013. During the last three decades, broilers, pigs and laying hens have been ascribed the role of main reservoirs for this pathogen in different time periods, thus demanding different control strategies in the food chain. In order to identify the main food-animal sources of human salmonellosis, Denmark has since 1995 relied on the routine application of a source attribution model.



The source attribution model uses a microbial subtyping approach to attribute cases to their animal reservoirs, i.e., it compares the number of human cases caused by different Salmonella subtypes with the distribution of the same subtypes isolated from various food-animal sources, also taking into account the differences in consumption of the meats/eggs included in the model.



The data required for the model are collected through national surveillance and monitoring programs involving food authorities, the food industry and national reference laboratories for animal and human samples, requiring a well-structured network which has been developed during the last two decades.



Traditionally, the model has used data on serotypes, phage types and antimicrobial resistance profiles of Salmonella isoltaes. Starting in 2014, molecular methods will be used for subtyping of Salmonella Enteritidis and Salmonella Typhimurium.



Results are published yearly in the Annual Report on Zoonoses in Denmark.