title: Prevalence, outcome, and health consequences associated with persistent infection with bovine viral diarrhea virus in feedlot cattle.
abstract: OBJECTIVE
  To estimate prevalence of cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV) at arrival at a feedlot, prevalence of chronically ill and dead PI cattle, and the magnitude of excess disease attributable to a PI animal.
  
  
  METHODS
  Cross-sectional and cohort studies.
  
  
  METHODS
  2,000 cattle at the time they arrived at a feedlot, 1,383 chronically ill cattle from 7 feedlots, and 1,585 dead cattle from a single feedlot.
  
  
  METHODS
  Skin biopsy specimens were collected and evaluated via immunohistochemistry. Cattle were characterized as either PI or not PI with BVDV on the basis of characteristic immunostaining. Follow-up was obtained for the 2,000 cattle from which samples were collected at arrival, and health outcomes were determined for cattle exposed and not exposed to a PI animal.
  
  
  RESULTS
  Prevalence of PI cattle was 0.3% at arrival, 2.6% in chronically ill cattle, and 2.5% in dead cattle. Risk of initial treatment for respiratory tract disease was 43% greater in cattle exposed to a PI animal, compared with those not exposed to a PI animal. Overall, 15.9% of initial respiratory tract disease events were attributable to exposure to a PI animal.
  
  
  CONCLUSIONS
  Relatively few PI cattle arrive at feedlots. However, those cattle are more likely to require treatment for respiratory tract disease and either become chronically ill or die than cattle that are not PI. In addition, they are associated with an increase in the incidence of respiratory tract disease of in-contact cattle.
authors.affiliation: Feedlot Research Group, Division of Agriculture, College of Agriculture, Nursing, and Natural Sciences, West Texas A&M University, Canyon, TX 79016, USA.
authors.forename: Guy H
authors.initials: GH
authors.lastname: Loneragan
authors.forename: Daniel U
authors.initials: DU
authors.lastname: Thomson
authors.forename: Donald L
authors.initials: DL
authors.lastname: Montgomery
authors.forename: Gary L
authors.initials: GL
authors.lastname: Mason
authors.forename: Robert L
authors.initials: RL
authors.lastname: Larson
mesh_terms: D000818:Animals; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000150:complications / Q000453:epidemiology* / Q000821:virology; D002417:Cattle; D002418:Cattle Diseases / Q000453:epidemiology* / Q000821:virology; D002908:Chronic Disease; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D001908:Diarrhea Viruses, Bovine Viral; D007150:Immunohistochemistry / Q000662:veterinary; D008297:Male; D012141:Respiratory Tract Infections / Q000150:complications / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D012867:Skin / Q000821:virology