Prevalence of Anaplasma phagocytophilum infection and effect on lamb growth |
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| Authors: | Lise Gr?va Ingrid Olesen H?vard Steinshamn Snorre Stuen |
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| Affiliation: | 1.Norwegian Institute for Agricultural and Environmental Research (Bioforsk), Organic Food and Farming Division, Gunnars veg 6, 6630 Tingvoll, Norway;2.Department of Animal and Aquacultural Science, Norwegian University of Life Sciences, Postbox 5003, 1432 Ås, Norway;3.Nofima Marin, Postboks 5010, 1432 Ås, Norway;4.Section for small ruminant research, Norwegian School of Veterinary Science, 4325 Sandnes, Norway |
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| Abstract: | BackgroundA major challenge in sheep farming during the grazing season along the coast of south-western Norway is tick-borne fever (TBF) caused by the bacteria Anaplasma phagocytophilum that is transmitted by the tick Ixodes ricinus.MethodsA study was carried out in 2007 and 2008 to examine the prevalence of A. phagocytophilum infection and effect on weaning weight in lambs. The study included 1208 lambs from farms in Sunndal Ram Circle in Møre and Romsdal County in Mid-Norway, where ticks are frequently observed. All lambs were blood sampled and serum was analyzed by an indirect fluorescent antibody assay (IFA) to determine an antibody status (positive or negative) to A. phagocytophilum infection. Weight and weight gain and possible effect of infection were analyzed using ANOVA and the MIXED procedure in SAS.ResultsThe overall prevalence of infection with A. phagocytophilum was 55%. A lower weaning weight of 3% (1.34 kg, p < 0.01) was estimated in lambs seropositive to an A. phagocytophilum infection compared to seronegative lambs at an average age of 137 days.ConclusionsThe results show that A. phagocytophilum infection has an effect on lamb weight gain. The study also support previous findings that A. phagocytophilum infection is widespread in areas where ticks are prevalent, even in flocks treated prophylactic with acaricides. |
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