Hasle et al. Acta Veterinaria Scandinavica 2010, 52:55 http://www.actavetscand.com/content/52/1/55 in incidence, and we may also see a climate-related increase. An increased incidence of B. divergens in cattle could have important economic and animal welfare con- sequences, and further studies are needed to evaluate whether it would be cost effective to implement preven- tive measures against the spread of this pathogen. Anti- body testing of pastured cows is a simple way of mapping the distribution of the pathogen. Acknowledgements Thanks to Ph. D. student Lise Heyer, Department of Biology, University of Oslo, Norway, for help with statistical analyses. Author details 1Department of Biology, University of Oslo, P.O. Box 1050 Blindern, N-0316 Oslo, Norway. 2Institute for Health and Society, Faculty of Medicine, University of Oslo, Norway. 3Department of Virology, Immunobiology and Parasitology. National Veterinary Institute, Uppsala, Sweden. 4Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Norway. 5Department of Cattle Health Services, TINE Norwegian Dairy Association, Norway. Authors’ contributions GH prepared the fieldwork, interviewed the farmers, performed all the blood sampling and wrote the main part of the paper. GB, KHR and HPL provided valuable and significant contributions to the writing of the paper. DC headed the laboratory work, and performed all the microscopy of the slides in the immunofluorescence antibody test. Furthermore, he contributed significantly to the writing of the paper. ACW contributed with data from the Norwegian Dairy Herd Recording System, and also contributed significantly to the writing of the paper. All authors read and approved the final manuscript Competing interests The authors declare that they have no competing interests. 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