bovine tuberculosis monaya ekgatat niah tbtb. - introduction - etiology & epidemiology -...
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Bovine Bovine
TuberculosiTuberculosiss
Monaya Ekgatat NIAH
TB
- Introduction
- Etiology & Epidemiology
- Clinical Signs
- Post mortem lesions
- Diagnosis- Public Health- Prevention and
control
Bovine Tuberculosis
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Zoonosis human- aerosol- ingestion
Developed countries- reduced prevalence
Less developed countries- still common- economic loss
Introduction
Control relies on- early diagnosis
- removal of infected animal- tracing- exposing infected cases
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Etiology and epidemiology
Agents
Mycobacterium tuberculosis (human)
Mycobacterium bovis (animal)
Mycobacterium avium (bird)
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Mycobacterium tubeMycobacterium tuberculosisrculosis complex complex (MTB. Complex)(MTB. Complex)
M. tuberculosis M. capraeM. caprae
M. bovis M. pinnipediiM. pinnipedii
M. africanum M. canetti
M. microti
Etiology and epidemiology
Mycobacterium bovisMycobacterium bovis
• Can survive for several months in the environment
(cold, dark and moist condition)
• 12-24 oC survival time 18-332 days
• Dry or moist soil (34 oC) : 4-8 weeks
• Summer : 4 days
Maintenance hosts for Maintenance hosts for M. bovisM. bovis
- cattle
- buffalo
Reservoir hostsReservoir hosts
- brush-tail possum (New Zealand)
- badger (United Kingdom, Ireland)
- deer (United States)
- bison (Canada)
- greater kudu, common duiker
African buffalo, warthogs (Africa)
Etiology and epidemiology
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Badger
African buffalo
Warthog
Common duiker
Greater kudu
Brush-tail possum
Etiology and epidemiology
TransmissionRespiration----aerosal (short distance)
Ingestion ( unpasteurized milk)
Source of infectious bacteria- respiratory secretion- feces- milk- (urine)- vaginal secretion- semen
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Incubation PeriodIncubation Period
• 3 weeks – years: under natural condition
Morbidity and MortalityMorbidity and Mortality
• 1-2 animals = 0 - 40% infected
= 0 - 10% developed gross lesions• Severity - dose of agents
- individual immunity• Mortality : rare
Clinical SignsClinical SignsChronic ( rare: acute & rapidly progressive)
Early infection ---- asymptomatic
Late stage: symptomatic- progressive emaciation- fluctuating fever- weakness- inappetite- moist cough (pulmonary involve)- dyspnea
No specific signs
Asymptomatic and anergic carriers (ill: stress, old age)
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Post mortem lesionsPost mortem lesions
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Lymphnodes: calcifiedLymphnodes: calcified
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Tubercles in liver
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Mesenteric lymph node
Diagnosis
• Clinical signs Clinical signs (lacking)(lacking)• Laboratory diagnosisLaboratory diagnosis
1. Identification of the agenta) Microscopic examinationb) Culture of M. bovis (3-6 weeks)
- biochemical tests - culture characteristics
c) Nucleic acid recognition methods
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2. Delayed hypersensitivity test
Tuberculin test : SID, SCITT
3. Blood-based laboratory tests
a) Gamma-interferon assay
b) Lymphocyte proliferation assay
c) ELISA
(late stages of infection, anergic cattle)
Diagnosis
Presumptive DiagnosisPresumptive Diagnosis
• Histopathology• Microscopic demonstration of acid-fast bacilli• Direct smear from clinical samples/tissues and
stained with Z-N stain, fluorescent acid-fast stain or immunoperoxidase
- Contagious bovine pleuropneumonia- Contagious bovine pleuropneumonia
- Pasteurella or Corynebacterium pyogenes pneumonia
- Aspiration pneumonia ( secondary infection)
- Traumatic pericarditis
- Caseous lymphadenitis or melioidosis (small ruminant)
- Chronic aberrant liver fluke infestation
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Differential DiagnosisDifferential Diagnosis
Laboratory Diagnosis
1. Identification and isolation of the agent
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M. bovisM. bovis: Cord Formation: Cord Formation
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M. bovisM. bovis: granule in P&B: granule in P&B
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Immunohistochemistry
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DNA - hybridization
ELISA: Detection of MTB complexELISA: Detection of MTB complex
1 2 3 1 2 3 1 2 3 1 2 3
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The immune system : Antigen
Antigen presenting cells(Macrophages & reticulocites)
Humoral immunity
B-lymphocytes
Plasma cells antibodies Lymphokines cytooxicity
T-lymphocytes
Cell mediated immunity
Diagnostic measures of an Immune response
ELISA Skin test / Lymphocyte stimulation / Gamma-interferon
Memory
Antigen:Bov. PPD 0.1 ml(not more than 0.2 ml) = 2,000 IU – 5,000 IU
Work plan
0 h 24 48 72 hrs
2.Tuberculin test
1stmeasureinjection
2ndmeasure
Negative reaction < 2 mm w/o local clinical signs
Inconclusive reaction 2-4 mm w/o local clinical signs
Positive reaction ≥ 4 mm with or w/o local clinical signs
(one fold + ≥ 8 mm)
Retest: after 42- 60 days (cattle), 120 days (deer) NIAH
Cervical Test
Caudal fold Test
Axillary Test
Base of the ear
Anywhere
Tuberculin test
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Positive reaction
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Tuberculin test at cervical
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Deer: Tuberculin test (cervical)
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a) a) Gamma-interferon assay (Gamma-interferon assay (IFN)IFN) – early detection
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33. Blood-based laboratory tests. Blood-based laboratory tests
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IFN Assay
b) Lymphocyte proliferation assayb) Lymphocyte proliferation assay
• Antigen : PPD-Bov, PPD-Avi• Not used for routine diagnosis
- long incubation times
- use of radio-active nucleotides• Expensive
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c) ELISA: complementary test
d) Chromatographic Immunoassay
Chromatographic Immunoassay
ChrChroomatographic Immunoassaymatographic Immunoassay
Samples CollectionSamples Collection
• Live animal
- body fluids: microbiological examination
- blood samples: IFN, lymphocyte proliferation
- serum: ELISA
• Necropsy
- abnormal lymph nodes
- affected organs (lung, liver and spleen)
For bacteriology and histopathology
Public Health
• Due to M. bovis : very rare• Asymptomatic• Localized: lymph nodes, skin, bones and joints,
genitourinary system, meninges or respiratory system
Prevention and ControlPrevention and Control
Sanitary ProphylaxisSanitary Prophylaxis
- Tuberculin Test slaughter
- Re-testing schedule for high risk herds
- Animal movement control, identification
and surveillance
- Disinfection Effective disinfectants: 5 % phenol, iodine solution, glutaraldehyde
and formaldehyde
Environment : 1% sodium hypochlorite (long contact time)
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- Quarantine measures
- Slaughter inspection surveillance
and trace - back
- Surveillance in other animals
- Pasteurisation of milk
Medical ProphylaxisMedical Prophylaxis No chemophophylaxis or treatment
Prevention and Control
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ControlControl
• Test-and-slaughter (domestic animals)
• Test-and-segregation
Affected Herds - re-tested periodically
Thank you for your attention
Thank you for your attention