Abstract
Background: Both bovine coronavirus (BCV) and bovine respiratory syncytial virus (BRSV) infections are currently
wide-spread in the Swedish dairy cattle population. Surveys of antibody levels in bulk tank milk have shown very high
nationwide prevalences of both BCV and BRSV, with large variations between regions. In the Swedish beef cattle
population however, no investigations have yet been performed regarding the prevalence and geographical
distribution of BCV and BRSV. A cross-sectional serological survey for BCV and BRSV was carried out in Swedish beef
cattle to explore any geographical patterns of these infections.
Methods: Blood samples were collected from 2,763 animals located in 2,137 herds and analyzed for presence of
antibodies to BCV and BRSV. Moran's I was calculated to assess spatial autocorrelation, and identification of
geographical cluster was performed using spatial scan statistics.
Results: Animals detected positive to BCV or BRSV were predominately located in the central-western and some
southern parts of Sweden. Moran's I indicated global spatial autocorrelation. BCV and BRSV appeared to be spatially
related: two areas in southern Sweden (Skaraborg and Skåne) had a significantly higher prevalence of BCV (72.5 and
65.5% respectively); almost the same two areas were identified as being high-prevalence clusters for BRSV (69.2 and
66.8% respectively). An area in south-east Sweden (Kronoberg-Blekinge) had lower prevalences for both infections
than expected (23.8 and 20.7% for BCV and BRSV respectively). Another area in middle-west Sweden (Värmland-
Dalarna) had also a lower prevalence for BRSV (7.9%). Areas with beef herd density > 10 per 100 km2 were found to be
at significantly higher risk of being part of high-prevalence clusters.
Conclusion: These results form a basis for further investigations of between-herds dynamics and risk factors for these
infections in order to design effective control strategies.