Dynamics of virus infections involved in the bovine respiratory disease complex in Swedish dairy herds.
The dynamics of bovine respiratory syncytial virus (BRSV), bovine parainfluenza virus 3 (PIV-3), bovine corona virus (BCoV) and bovine viral diarrhoea virus (BVDV) infections were studied in 118 dairy herds in south western Sweden. By using serology on paired samples from three approximately 7 vs. approximately 15-month-old calves per herd, the propagation of infections was investigated over about a 1-year period. The results implied that at least 74% of calves had experienced one or more of the monitored infections at the age of approximately 7 months (Sample 1, Spring); 30%, 48%, 34% and 8% were seropositive to BRSV, PIV-3, BCoV and BVDV, respectively. Seroconversions to BRSV, PIV-3, BCoV and BVDV occurred in 26%, 38%, 50% and 3% of seronegative animals and 63% had antibodies against two or more infections at approximately 15 months (Sample 2). In total, 90-97% of animals that were seropositive in Sample 1 remained positive in Sample 2. A significant association was found between BVDV and BCoV (P = 0.01). Moreover, a significantly higher proportion of herds in which no calves had a recorded history of respiratory disease (n = 15) were classified as negative to all four infections monitored when compared to herds in which disease was observed (P = 0.0002). This study showed a high infection burden in young animals and effective spread of BRSV, PIV-3 and BCoV in one area of Sweden. BVDV infections were restricted to a few herds, reflecting the effect of a voluntary control program against BVDV in Sweden.
Hägglund
S
S
Swedish University of Agricultural Sciences, Department of Clinical Sciences, Division of Ruminant Medicine and Veterinary Epidemiology, P.O. Box 7019, SE-75007 Uppsala, Sweden. sara.hagglund@kv.slu.se
Svensson
C
C
Emanuelson
U
U
Valarcher
J F
JF
Alenius
S
S
D000822:Animal Husbandry; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology / Q000821:virology*; D005260:Female; D012327:RNA Virus Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D012328:RNA Viruses / Q000302:isolation & purification*; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D016036:Seroepidemiologic Studies; D013548:Sweden / Q000453:epidemiology