Source attribution of human Salmonella cases in Sweden

The aim of this study was to identify the sources of sporadic domestic Salmonella cases in Sweden and to evaluate the usefulness of a source-attribution model in a country in which food animals are virtually free from Salmonella. The model allocates human sporadic domestic Salmonella cases to different sources according to distribution of Salmonella subtypes in the different sources. Sporadic domestic human Salmonella cases (n = 1086) reported between July 2004 and June 2006 were attributed to nine food-animal and wildlife sources. Of all Salmonella cases, 82% were acquired abroad and 2.9% were associated with outbreaks. We estimated that 6.4% were associated with imported food, 0.5% with food-producing animals, and 0.6% with wildlife. Overall, 7.7% could not be attributed to any source. We concluded that domestic food-producing animals are not an important source for Salmonella in humans in Sweden, and that the adapted model is useful also in low-prevalence countries.