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Geographical distribution of salmonella infected pig, cattle and sheep herds in Sweden 1993-2010

Susanna Sternberg Lewerin12*, Lars Skog3, Jenny Frössling14 and Helene Wahlström1

Author Affiliations

1 National Veterinary Institute, Department of Disease Control and Epidemiology, SE-751 89 Uppsala, Sweden

2 Swedish University of Agricultural Sciences, Department of Biomedical Sciences and Veterinary Public Health, Box 7028, SE-750 07 Uppsala, Sweden

3 Royal Institute of Technology, Geoinformatics, SE-100 44 Stockholm, Sweden

4 Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Box 7084, SE-750 07 Uppsala, Sweden

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Acta Veterinaria Scandinavica 2011, 53:51  doi:10.1186/1751-0147-53-51

Published: 5 October 2011



The Swedish salmonella control programme covers the entire production chain, from feed to food. All salmonella serotypes are notifiable. On average, less than 20 cases of salmonella in food-producing animals are reported every year. In some situations, the cases would be expected to cluster geographically. The aim of this study was to illustrate the geographic distribution of the salmonella cases detected in pigs, cattle and sheep.


Data on all herds with pigs, cattle and sheep found to be infected with salmonella during the time period from 1993 to 2010 were obtained from the Swedish Board of Agriculture. Using the ArcGIS software, various maps were produced of infected herds, stratified on animal species as well as salmonella serotype. Based on ocular inspection of all maps, some were collapsed and some used separately. Data were also examined for temporal trends.


No geographical clustering was observed for ovine or porcine cases. Cattle herds infected with Salmonella Dublin were mainly located in the southeast region and cattle herds infected with Salmonella Typhimurium in the most southern part of the country. Some seasonal variation was seen in cattle, but available data was not sufficient for further analyses.


Analyses of data on salmonella infected herds revealed some spatial and temporal patterns for salmonella in cattle. However, despite using 18 years' of data, the number of infected herds was too low for any useful statistical analyses.