title: Spatiotemporal patterns, annual baseline and movement-related incidence of Streptococcus agalactiae infection in Danish dairy herds: 2000-2009.
abstract: Several decades after the inception of the five-point plan for the control of contagious mastitis pathogens, Streptococcus agalactiae (S. agalactiae) persists as a fundamental threat to the dairy industry in many countries. A better understanding of the relative importance of within- and between-herd sources of new herd infections coupled with the spatiotemporal distribution of the infection, may aid in effective targeting of control efforts. Thus, the objectives of this study were: (1) to describe the spatiotemporal patterns of infection with S. agalactiae in the population of Danish dairy herds from 2000 to 2009 and (2) to estimate the annual herd-level baseline and movement-related incidence risks of S. agalactiae infection over the 10-year period. The analysis involved registry data on bacteriological culture of all bulk tank milk samples collected as part of the mandatory Danish S. agalactiae surveillance scheme as well as live cattle movements into dairy herds during the specified 10-year period. The results indicated that the predicted risk of a herd becoming infected with S. agalactiae varied spatiotemporally; the risk being more homogeneous and higher in the period after 2005. Additionally, the annual baseline risks yielded significant yet distinctive patterns before and after 2005 - the risk of infection being higher in the latter phase. On the contrary, the annual movement-related risks revealed a non-significant pattern over the 10-year period. There was neither evidence for spatial clustering of cases relative to the population of herds at risk nor spatial dependency between herds. Nevertheless, the results signal a need to beef up within-herd biosecurity in order to reduce the risk of new herd infections.
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 8, DK-1870 Frederiksberg C, Denmark. Electronic address: mweu@sund.ku.dk.
authors.forename: Marshal M
authors.initials: MM
authors.lastname: Mweu
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 8, DK-1870 Frederiksberg C, Denmark.
authors.forename: Søren S
authors.initials: SS
authors.lastname: Nielsen
authors.affiliation: Division of Veterinary Diagnostics and Research, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, DK-1870 Frederiksberg C, Denmark.
authors.forename: Tariq
authors.initials: T
authors.lastname: Halasa
authors.affiliation: Department of Large Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 8, DK-1870 Frederiksberg C, Denmark; Division of Veterinary Diagnostics and Research, National Veterinary Institute, Technical University of Denmark, Bülowsvej 27, DK-1870 Frederiksberg C, Denmark.
authors.forename: Nils
authors.initials: N
authors.lastname: Toft
mesh_terms: D000818:Animals; D002417:Cattle; D003198:Computer Simulation; D003612:Dairying; D003718:Denmark / Q000453:epidemiology; D005260:Female; D015994:Incidence; D008414:Mastitis, Bovine / Q000453:epidemiology / Q000382:microbiology* / Q000517:prevention & control; D008892:Milk / Q000382:microbiology*; D009010:Monte Carlo Method; D013029:Space-Time Clustering; D013290:Streptococcal Infections / Q000453:epidemiology / Q000382:microbiology / Q000517:prevention & control / Q000662:veterinary*; D013292:Streptococcus agalactiae / Q000302:isolation & purification*
keywords: Biosecurity; Cattle; Incidence; Spatiotemporal; Streptococcus agalactiae