| Pathogenesis
|
| Once infection
is established the organisms are carried from the point of entry to the
regional lymph nodes, leading to acute lymphadenitis. |
| Bacteria multiply inside
phagocytes and disseminate via systemic circulation to other organs or tissues
such as the spleen, lymph nodes, uterus and the mammary gland. In males,
B. abortus can be found mostly in the testicles where the organisms cause
orchitis, and accessory sex glands as well as lymphoid tissue. The bacteremia
can last for months, and in cases of chronic disease it can be intermittent,
recurring mostly around parturition. |
 |
| The bacteria
localize in the uterus during gestation and cause ulceration of the endometrium.
The initial lesions are seen in the wall of the uterus, but the organism
quickly spreads to the placental cotyledons and destroys the villi. Depending
on the severity of the lesions potential sequelae include: abortion, especially
in the last trimester, stillbirths, and premature or weak calves. Following
abortion or parturition the organism is shed by the uterus for weeks, and
the animal remains infected for life. |
 |
 |