Causative agent
- Brucella abortus
Differential diagnosis
- Bovine campylobacteriosis
- Bovine salmonellosis - Trichomoniasis
- Akabane disease - Bovine chlamydiosis
- Leptospirosis - Mycological abortion
1. History taking
- Introduction of cattle from infected herd
- Previous occurrence within the farm
- Multiple abortions at advanced pregnancy
2. Clinical examination
- Abortion
- Retention of the placenta
- Asymptomatic in nonpregnant females
- Sterility
- Orchitis and epididymitis in bull
3. Serological tests
Specimen: serum and milk
- Screening tests
*Rose bengal plate test (RBPT)
antigen 0.03 ml + serum 0.03 ml mix and rock for 4
minutes and observe the agglutination
Any visible reaction is considered to be positive
*Rapid plate test (RPT)
Drop serum 0.08, 0.04, 0.02 and 0.01 ml dilutions
on a glass plate in 1x1 inch squares and drop antigen 0.03 ml to each dilution then mix and rotate for 5-8 minutes
Observe for agglutination (any visible reaction is considered to be positive in each dilution)
- Confirmation tests
Tube agglutination test (EDTA or 2 ME treatment
Complement fixation test (CFT), ELISA
4. Necropsy
- No significance in diagnosis
- Necrotizing placentitis and disseminated
inflammatory reactions in aborted fetal tissues
are characteristic changes
- Granulomatous lesions and focal necrosis in
several organs
5. Histopathological observation
- Granulomatous lesions
- "Brucella nodule" formation
- Immunohistochemistry : demonstration of
intracellular Brucella organism
|
6. Bacterial isolation
(All procedures must be done in biohazard cabinet)
Specimen : aborted fetal tissues and contents of
stomach, small intestine and cecum from
aborted fetus, milk, samples of tissue
collected at post-mortem such as
supramammary and other lymph nodes
from female, testes and related lymph
nodes from male, visceral organs and
lochia
Medium : selective medium (agar 7.5 g, trypticase
soy broth 15 g, D.W. 500 ml, horse
serum 25 ml and Brucella selective
antibiotics 1 vial) biphasic medium
(castaneda medium)
Culture : lymph nodes and organs, grind in PBS,
inoculate on media and incubate at 37°C
under 5-10% CO2 condition for 5-7 days
- Characteristics of colony : raised convex, circular
outline, transparent, smooth surface and slow
growing, Gram negative coccobacilli or short rods
- Tentative identification : oxidase and urease tests
are positive and prove agglutination test with
monospecific antiserum
Differential characteristics of the species in genus Brucella
|
| |
Growth on dye agar |
| |
Basic |
|
Thionin |
|
CO2 |
H2S |
fuchsin |
|
|
Requirement |
product |
1:50,000 |
|
1:25,000 |
1:50,000 |
| Br.melitensis |
- |
- |
+ |
|
- |
+ |
| Br.abortus |
d |
d |
+* |
|
- |
d |
| Br.suis |
- |
d |
d |
|
d |
+ |
| Br.neotomae |
- |
+ |
- |
|
- |
+ |
| Br.ovis |
+ |
- |
+ |
|
+ |
+ |
| Br.canis |
- |
- |
- |
|
+ |
+ |
| *Br. abortus Type 3: + d : difference by strains. |
Control and Prevention
- Test and slaughter of reservoir of infection
- Quarantine for imported cattle
- Depopulation (Regular serum examination)
- Calfhood vaccination : Application the strain 19
vaccine of Br. abortus in female young calves age
3-8 months (1 time)
Precaution
- Brucella sp. is a zoonotic agent
- Vaccine Br. abortus strain 19 is an attenuated
strain and still capable of causing disease in
humans. It must be handled under appropriate
conditions
- Disinfectants : phenolic, iodophor, aldehyde-
formulation, 2% medol, 2% lysol, 2% biogram
- Field personnel should handle the specimens
under appropriate procedures |
