title: Salmonella dublin in Danish dairy herds: frequency of change to positive serological status in bulk tank milk ELISA in relation to serostatus of neighbouring farms.
abstract: Bulk tank milk from 1,429 herds were collected in 3 rounds from 19 different geographic areas. The milk samples were tested by use of indirect LPS-ELISA procedure to detect Salmonella dublin antibodies. From the obtained OD-values herd seroprevalence in the given area was determined and GR-scores calculated for each herd by addition of the number of positive sampling rounds by the 5 geographically closest neighbour herds. In the 19 different areas the calculated prevalence ranged from 0.01 to 0.41. Totally 3,697 GR-scores were given. The mean GR-scores in the areas ranged from 0.0 to 6.5. Higher GR-scores were found in herds changing to seropositive status compared with herds seronegative throughout the study period. The results indicate that the risk for a dairy herd to receive S. dublin infection increases with the disease status among the nearest neighbours and with the prevalence of seropositive herds in the geographic area.
authors.affiliation: Cattle Health Laboratory, Danish Dairy Board, Brørup, Denmark. awe@svs.dk
authors.forename: A
authors.initials: A
authors.lastname: Wedderkopp
authors.forename: U
authors.initials: U
authors.lastname: Strøger
authors.forename: P
authors.initials: P
authors.lastname: Lind
mesh_terms: D000818:Animals; D002417:Cattle; D003718:Denmark / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D008892:Milk / Q000382:microbiology*; D012307:Risk Factors; D012475:Salmonella / Q000302:isolation & purification*; D012481:Salmonella Infections, Animal / Q000453:epidemiology*; D016036:Seroepidemiologic Studies