6. EPIDEMIOLOGY
Brucella exist world wide ( rare in industrialized countries)
Mediterranean , India , Mexico , central and south America
Risk factor :
1. exposure to infected animals and animal’s product
2. Inhalation of infected aerosols
7. PATHOGENESIS
Rout of infection:
1. Skin ( cut and abrasions )
2. Inhalation ( infected aerosol )
3. Ingestion ( meat and dairy products )
4. Inoculation ( conjunctival sac of the eye )
8. PATHOGENESIS……..
Risk for infection depend on:
1. Nutritional status
2. Immune status
More virulent species
1. Brucella melitensis
2. Brucella suis
Smooth lipopolysaccharide
of cell wall
9. PATHOGENESIS……
This organism is Facultative intracellular and can:
1. Survive and replicate in monocyte and macrophage
2. Ingested by macrophage and localize within RES
3. Granuloma formation
10. PATHOGENESIS…..
The major factor in recovery:
1. Antibody against lipopolysaccharide and cell wall
2. Cell mediated response (macrophage activation enhance
intracellular killing)
3. Sensitized T lymphocyte (interferon gamma ,TNF alpha)
11. CLINICAL FEATURES
Brucellosis is a systemic illness and can be:
1. Acute ( < 2months )
2. Subacute ( 2 – 12 months )
3. Chronic ( > 1 years )
Incubation period : 7days – 3months
Symptoms generally beginning 2-4 weeks after exposure
12. CLINICAL FEATURES…..
Most patient have classic triad:
1. fever ( FUO ) : continues or intermittent and persist for several months.
2. arthralgia / arthritis: particularly knee , hip , ankle (child) sacroiliac ( adult )
3. hepatosplenomegaly
Less common lymphadenopathy
13. CLINICAL FEATURES….
Other symptoms include:
1. Refuse to bear weight on an extremity + fever = typical presentation
2. Headache
3. Pharyngitis
4. Cough
5. vomiting
6. Abdominal pain
7. Diarrhea
8. Rashes
9. Night sweats
10. Weakness
14. CLINICAL FEATURES….
Invasion of nervous system can cause: 1%
1. Headache
2. Mental change
3. Depression
4. Symptom of meningitis
16. ORGAN SYSTEMS OF
INVOLVEMENT
Skeletal system :
1. Arthritis
2. Movement limitation , swelling and tenderness of affected joint
3. Disclosing hip
4. Vertebral involvement
1. MRI
2. Radionuclide bone
scan
3. ultrasound
17. CENTRAL NERVOUS SYSTEM
1. Meningitis
2. encephalitis
3. Myelitis
4. Neuritis
5. Mycotic aneurysm
6. Brain abscess
23. HEMATOLOGIC SYSTEM
Mild hematologic abnormalities are
1. Anemia
2. Lymphocytosis
3. Thrombocytopenia
Rare life threatening complications are:
1. Pancytopenia
2. Thrombocytopenic purpura
3. Mucosal bleeding
24. DIAGNOSIS
1. History of exposure
2. Laboratory findings :
•Blood culture (gold standard) : prior to antibiotic therapy
•Bone marrow culture when organism is in RES (even after antibiotic)
•Serum agglutination test ( =>1:160 or =>1:320 ) except of B.canis
•ELISA (IgG and IgM)