TABLE 3.
Virulence of B. abortus 2308 and BHB1 (ΔdhbC) in pregnant cattle
| Strain | No. of heifers with result/no. tested
|
||
|---|---|---|---|
| Maternal colonizationa,b | Fetal colonizationb,c | Fetal pathologyd | |
| 2308 | 10/10 | 10/10 | 8/10 |
| BHB1 | 1/10e | 1/10e | 1/10e |
a
B. abortus (≥ 1 CFU) isolated from a vaginal swab and/or one or more of the following tissues from the heifer: parotid, internal iliac, or supramammary lymph node, mammary gland, or milk.
b
B. abortus isolates were identified by standard biochemical reactions and their reactivity with B. abortus antiserum.
c
B. abortus (≥1 CFU) isolated from the lungs and/or abomasal fluid of the fetus or calf.
d
Fetus aborted or birth of a weak calf (e.g., a calf that cannot stand alone and cannot or will not nurse).
e
P ≤ 0.005 versus 2308 by Fisher's exact test (41).