Hasle et al. Acta Veterinaria Scandinavica 2010, 52:55 http://www.actavetscand.com/content/52/1/55 R E S E A R C H Open Access Detection of Babesia divergens in southern Norway by using an immunofluorescence antibody test in cow sera Gunnar Hasle1,2*, Gunnar A Bjune2, Dan Christensson3, Knut H Røed4, Anne C Whist5, Hans P Leinaas1 Abstract Background: The incidence of bovine babesiosis, caused by Babesia divergens (Apicomplexa: Piroplasmida) has decreased markedly since the 1930 s, but may re-emerge as a consequence of climate change and changes in legislation and pasturing practices. This is a potentially serious disease, with both economical and animal welfare consequences. Therefore, there is a need to survey the distribution of B. divergens. Methods: We tested sera from 306 healthy pastured cows from 24 farms along the southern Norwegian coast by using an indirect immunofluorescence IgG antibody test (IFAT). Fractions of seropositive cows were compared by calculating 95% CI. Results: The results of this test showed that 27% of the sera were positive for B. divergens antibodies. The fraction of antibody-positive sera that we detected showed a two-humped distribution, with a high fraction of positives being found in municipalities in the western and eastern parts of the study area, while the municipalities between these areas had few or no positive serum samples. Conclusions: Neither the farmers’ observations nor the Norwegian Dairy Herd Recording System give an adequate picture of the distribution of bovine babesiosis. Serological testing of cows by using IFAT is a convenient way of screening for the presence of B. divergens in an area. Background Though the incidence of bovine babesiosis is low in Norway, these pathogens have immense economic importance throughout the world, with the highest pre- valence being found in the tropics [1]. The costs asso- ciated with this infection are associated with mortality, ill-thrift, abortions, loss of milk and meat production as well as with measures taken to control its spread [2]. Babesia divergens is the main cause of bovine babesiosis in northern Europe [3], although B. major, occurs in southeast England, Holland and the Friesian Islands in Germany [4]. Babesia species are intraerythrocytic pro- tozoa that cause fever, haemoglobinuria (redwater) and anaemia in cattle that are exposed to the parasite as adults. Calves are relatively resistant to B. divergens [5,6] and exhibit mild or no effects of the disease, while * Correspondence: hasle@reiseklinikken.com 1Department of Biology, University of Oslo, P.O. Box 1050 Blindern, N-0316 Oslo, Norway Full list of author information is available at the end of the article infected adults may have a high mortality [7,8]. Babesia spp. can cause serious infections in humans who do not have a functioning spleen or who are immunocompro- mised as a result of immunosuppressive drugs, malig- nancy or HIV-infection [9]. The only case of human B. divergens diagnosed in Norway is a splenectomised veterinarian in Western Norway in 2007 (personal com- munication, Kristine Mørch, Haukeland University Hospital). Cattle are the only natural vertebrate host for B. diver- gens. Reindeer and gerbils, and splenectomised indivi- duals of other species may be infected experimentally. Sheep, wild cervids and rodents that occur in the area where it is distributed are all considered to be resistant to B. divergens [3]. However, this issue is controversial, as new studies indicate that roe deer and red deer may be infected by B. divergens [10,11]. The vector of B. divergens in Western Europe is Ixodes ricinus (Acari: Ixodidae) [3], which can parasitise a wide range of verte- brates [12]. Vertebrate hosts may act as vehicles for © 2010 Hasle et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.