Attribution of Foodborne Pathogens Using Structured Expert Elicitation

Objectives: To estimate the fraction of human cases of enterically transmitted illness by five major pathways (food, environment, direct animal contact, human-human transmission, and travel) and by 11 groups within the food pathway. Methods: Food safety experts were asked to provide their estimates of the most likely range for each of the parameters. Joint probability distributions were created by probabilistic inversion (PI). Results: Sixteen experts participated in the study. PI resulted in good fits for most pathogens. Qualitatively, expert estimates were similar to earlier published studies but the estimated fraction of foodborne transmission was lower for most pathogens. Biologically less plausible pathways were given some weight by the experts. Uncertainties were smallest for pathogens with dominant transmission routes. Conclusions: Structured expert studies are a feasible method for source attribution, but methods need further development. Applications: These estimates can be combined with data on incidence, disease burden and costs to provide specific estimates of the public health impact of foodborne illness, and to identify the food groups that have the highest impact.