Impact of persistent bovine viral diarrhea viral infection on the duration and level of shedding of Escherichia coli O157 in calves.
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.
Sreerama
Sruti
S
Department of Clinical Sciences, Kansas State University, Manhattan, Kansas 66506-5701, USA.
Sanderson
Michael W
MW
Wilkerson
Melinda
M
Nagaraja
T G
TG