Objective—To compare experimentally induced concurrent
infection with bovine viral diarrhea virus
(BVDV) and bovine rotavirus (BRV) with infection of
either virus alone in calves.
Animals—Seventeen 1-day-old gnotobiotic calves.
Procedure—Calves were allotted to 8 treatments as
follows: group 1, mock-infected control calves (n = 2);
group 2, inoculated with BVDV on day 1 (2); groups 3,
5, and 7, inoculated with BRV on days 1 (2), 4 (1), or 7
(2), respectively; and groups 4, 6, and 8, inoculated
with BVDV on day 1 and with BRV on days 1 (2), 4 (2),
or 7 (4), respectively. Concentrations of BVDV in
serum and ileal tissues were measured, and BRV
shedding in feces was determined. Histologic examination
and immunohistochemical analysis were conducted
to detect lesions and viral antigens.
Results—Neonatal calves inoculated with BVDV
alone or with BVDV on day 1 and BRV on day 7 developed
villus atrophy and submucosal inflammation of
the intestines. Concurrent BVDV and BRV infections
acted synergistically in the intestinal tract, causing
more severe enteric disease than infection with either
virus alone. Severe lymphoid depletion was associated
with BVDV infection in calves regardlesss of concurrent
Conclusions and Clinical Relevance—Infection with
BVDV played direct and indirect roles in enteritis in
neonatal calves, causing villus atrophy in the duodenum
and submucosal inflammation of the intestines.
Also, BVDV potentiated effects of BRV. Concurrent
infection with BVDV and BRV resulted in more severe
enteric disease in neonatal calves than infection with
BRV or BVDV alone. (Am J Vet Res 2002;63:1179–1186)
Objective−To report the prevalence of bovine viral diarrhea virus (BVDV) in calves and calf groups (ie, calves from the same farm) in beef breeding herds and evaluate the ability of biosecurity risk assessment questionnaires to identify calf groups with positive results for BVDV.
Animals−12,030 calves born in spring from 102 operations.
Procedures−Cow-calf producers that voluntarily enrolled in a screening project submitted ear notch specimens from calves and answered a 29-question survey instrument. Ear notch specimens were tested for BVDV with an antigen-capture ELISA (ACE), and ear notch specimens with positive ACE results for BVDV were immediately retested by performing immunohistochemistry (IHC). Follow-up testing, 3 to 4 weeks after initial positive ACE results, was done by use of a second IHC test and virus isolation on a subsequently submitted ear notch specimen from the same calves to identify those that were persistently infected (PI).
Results−102 producers submitted ear notch specimens for BVDV screening. Initially, 24 of 12,030 calves had positive ACE results for BVDV. A second ear notch specimen was submitted for 20 of these 24 calves. Of 20 retested calves, 12 had positive ICH results for BVDV, confirming PI status. The 12 PI calves came from 4 calf groups (3 singletons and 1 calf group with 9 PI calves).
Conclusions and Clinical Relevance−Prevalence of BVDV in calf groups was low, and questions designed to identify high-risk biosecurity behaviors had little value in identifying calf groups with positive results for BVDV.