Spatial modelling of the between-herd infection dynamics of bovine virus diarrhoea virus (BVDV) in dairy herds in Denmark.
According to the current literature BVDV-infected neighbours probably impose a high risk of infection of susceptible cattle herds. In the present study, the objective was to evaluate the risk of a dairy herd changing infection status (from not having persistently infected (PI) animals to having PI-animals) in relation to location and infection status of neighbouring cattle herds in Denmark. In total, 7921 dairy herds were included in the analysis of spatial and non-spatial risk factors. The spatial risk factors were derived based on the cattle herds in the neighbourhood (N=36,639 cattle herds). The neighbourhood was defined as the first order neighbouring cattle herds using a Delauney triangularization. In total, 13.3% of the dairy herds changed herd status to PI-herds during the study period that lasted from January 1, 1995, to June 30, 1996. The risk of becoming a PI-herd was negatively associated with the mean distance to the neighbouring herds (OR=0.7 for an increase of 1 km). Presence of PI-herds in the neighbourhood increased the risk of becoming a PI-herd (OR=1.37, 1.40, 1.70 for 1, 2, ≥3 PI-herds in the neighbourhood). Increasing herd size increased the risk of becoming a PI-herd (OR=3.9 for an increase of 10 cows). Regional differences were seen.
Ersbøll
A K
AK
Department of Large Animal Sciences, Faculty of Life Sciences, University of Copenhagen, Grønnegårdsvej 8, DK-1870 Frederiksberg C, Denmark. ake@niph.dk
Ersbøll
B K
BK
Houe
H
H
Alban
L
L
Kjeldsen
A M
AM
D000818:Animals; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000453:epidemiology* / Q000635:transmission*; D002417:Cattle; D003612:Dairying; D003710:Demography; D003718:Denmark / Q000453:epidemiology; D001908:Diarrhea Viruses, Bovine Viral / Q000302:isolation & purification*; D005260:Female; D011157:Population Dynamics; D012307:Risk Factors