title: Impact of persistent bovine viral diarrhea viral infection on the duration and level of shedding of Escherichia coli O157 in calves.
abstract: OBJECTIVE
  The goal of this study was to determine whether calves persistently infected with bovine viral diarrhea virus (BVDV) and inoculated with Escherichia coli O157 will shed the organism at a higher concentration and for a longer duration than calves not infected with BVDV.
  
  
  METHODS
  Nine calves, 6-8 weeks old, persistently infected with noncytopathic BVDV and eight calves not infected with BVDV obtained from separate cow-calf operations were used in this study. BVDV status, positive or negative, of all calves was confirmed by repeated testing throughout the study. Both groups were orally inoculated with 10(9) colony-forming units (CFU) of five nalidixic acid-resistant strains of E. coli O157. All calves were examined daily, and fecal samples were collected three times a week for 55 days for detection and enumeration of the nalidixic acid-resistant E. coli O157. Calves were then necropsied, and samples from the gastrointestinal tract were taken for the detection of the nalidixic acid-resistant E. coli O157.
  
  
  RESULTS
  Data analysis indicated no statistical difference in the concentration of E. coli O157 shed or the duration of shedding between the persistently infected BVDV calves and the control calves throughout the length of the study.
  
  
  CONCLUSIONS
  Our data indicate that persistent infection with noncytopathic BVDV does not play a role in the level or duration of shedding of E. coli O157 in cattle.
authors.affiliation: Department of Clinical Sciences, Kansas State University, Manhattan, Kansas 66506-5701, USA.
authors.forename: Sruti
authors.initials: S
authors.lastname: Sreerama
authors.forename: Michael W
authors.initials: MW
authors.lastname: Sanderson
authors.forename: Melinda
authors.initials: M
authors.lastname: Wilkerson
authors.forename: T G
authors.initials: TG
authors.lastname: Nagaraja