title: Risk factors associated with herd-level exposure of cattle in Nebraska, North Dakota, and South Dakota to bluetongue virus.
abstract: OBJECTIVE
  To evaluate herd-level risk factors for seropositive status of cattle to 1 or more bluetongue viruses.
  
  
  METHODS
  110 herds of cattle in Nebraska, North Dakota, and South Dakota.
  
  
  METHODS
  Blood samples were collected before and after the vector season. Samples were tested for antibodies against bluetongue virus by use of a commercially available competitive ELISA. Factors evaluated included descriptors of geographic location and management practices. Trapping of insect vectors was conducted to evaluate vector status on a subset of 57 operations. A multivariable logistic regression model was constructed to evaluate associations.
  
  
  RESULTS
  For the full data set, altitude and latitude were associated with risk of having seropositive cattle (an increase in altitude was associated with an increase in risk, and a more northerly location was associated with a decrease in risk of a premise having seropositive cattle). Import of cattle from selected states was associated with an increase in risk of having seropositive cattle. From the subset of herds with data on vector trapping, altitude and latitude were associated with risk of having seropositive cattle, similar to that for the full model. However, commingling with cattle from other herds was associated with a decrease in risk of seropositivity.
  
  
  CONCLUSIONS
  Findings reported here may be useful in generating additional hypotheses regarding the ecologic characteristics of bluetongue viruses and other vector-borne diseases of livestock. Sentinel surveillance programs are useful for documenting regionalization zones for diseases, which can be beneficial when securing international markets for animals and animal products.
authors.affiliation: USDA, Animal and Plant Health Inspection Service, Veterinary Services, Centers for Epidemiology and Animal Health, 2150 Centre Ave, Bldg B, Mail Stop 2E7, Fort Collins, CO 80526-8117, USA.
authors.forename: Alice L
authors.initials: AL
authors.lastname: Green
authors.forename: David A
authors.initials: DA
authors.lastname: Dargatz
authors.forename: Edward T
authors.initials: ET
authors.lastname: Schmidtmann
authors.forename: Marco V
authors.initials: MV
authors.lastname: Herrero
authors.forename: Ann H
authors.initials: AH
authors.lastname: Seitzinger
authors.forename: Eileen N
authors.initials: EN
authors.lastname: Ostlund
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Wagner
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Moser
authors.forename: Nora E
authors.initials: NE
authors.lastname: Wineland
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Walton
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D001819:Bluetongue / Q000453:epidemiology*; D001820:Bluetongue virus / Q000276:immunology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology*; D016015:Logistic Models; D009329:Nebraska / Q000453:epidemiology; D009658:North Dakota / Q000453:epidemiology; D016017:Odds Ratio; D015995:Prevalence; D012307:Risk Factors; D016036:Seroepidemiologic Studies; D012756:Sheep; D013023:South Dakota / Q000453:epidemiology
chemical_list: D000914:Antibodies, Viral