A field-study on Leptospira seroprevalence in dairy cows in four geographical areas in Sweden

BACKGROUND Dairy cattle were used as sentinels for the presence of Leptospira infection in Swedish livestock in four regions contrasting in precipitation and temperature during the summer time. The aim of the study was to estimate the prevalence of five serovars of Leptospira of low pathogenicity in dairy cattle in these four regions. FINDINGS Around 150 blood samples were collected from five dairy farms from each region, making 610 samples in total, during December 2009. The samples were screened for L. kirschneri sv Grippotyphosa, L. interrogans sv Icterohaemorrhagiae, L. interrogans sv Canicola, L. borgpetersenii sv Sejroe and one domestic strain similar to sv Sejroe, called strain Mouse 2A using the Microscopic Agglutination Test. Six animals (1%) were seropositive for the strain Mouse 2A. Four of the positive samples were from the south-west region which also was the region with highest precipitation. There were no positive samples to any of the other serovars studied. CONCLUSIONS The present data indicate that there is a low seroprevalence of Leptospira in Swedish dairy cows. These findings can be used as baseline data to investigate the effects of, for instance, climatic change or alterations in wildlife reservoir populations on the seroprevalence of Leptospira in the future.