title: Association between the level of antibodies in bulk tank milk and bovine respiratory syncytial virus exposure in the herd.
abstract: Antibody levels in bulk tank milk (BTM) against bovine respiratory syncytial virus (BRSV) are used to classify BRSV status of herds. The aim of this study was to investigate how these levels correspond with the time at which the herds were infected. Bulk tank milk, individual milk and serum samples from cows and young stock were investigated using an indirect ELISA. Screenings of BTM from 89 dairy herds during two winter seasons revealed a prevalence of positive herds from 82 per cent to 85 per cent. Eleven herds showed a marked increase in antibody levels between two screenings, indicating new infection. However, two of these herds had been free from BRSV for the last five to seven years. Two newly infected herds were monitored for four years and did not appear to get reinfected. Surprisingly, the BTM antibody levels in these herds remained high throughout the study period, but fluctuated significantly. This shows that the levels of antibodies in BTM can remain high for several years, even in herds where reinfection does not occur. BTM serology is a useful tool in the monitoring of infectious diseases in dairy herds, but has limitations as a diagnostic tool for BRSV infections.
authors.affiliation: Department of Production Animal Clinical Sciences, Norwegian University of Life Sciences, P.O. Box 8146 Dep., Oslo NO-0033, Norway.
authors.forename: T B
authors.initials: TB
authors.lastname: Klem
authors.affiliation: Norwegian Veterinary Institute, P.O. Box 750 Sentrum, Oslo NO-0106, Norway.
authors.forename: T
authors.initials: T
authors.lastname: Tollersrud
authors.affiliation: Department of Cattle Health Services, TINE Norwegian Dairies, P.O. Box 58, Oslo NO-1431 Ås, Norway.
authors.forename: O
authors.initials: O
authors.lastname: Osterås
authors.affiliation: Department of Production Animal Clinical Sciences, Norwegian University of Life Sciences, P.O. Box 8146 Dep., Oslo NO-0033, Norway.
authors.forename: M
authors.initials: M
authors.lastname: Stokstad
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000032:analysis*; D002417:Cattle; D002418:Cattle Diseases / Q000175:diagnosis / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D008892:Milk / Q000276:immunology*; D011159:Population Surveillance / Q000379:methods; D018357:Respiratory Syncytial Virus Infections / Q000175:diagnosis / Q000276:immunology / Q000662:veterinary*; D018112:Respiratory Syncytial Virus, Bovine / Q000276:immunology*
chemical_list: D000914:Antibodies, Viral