bovine tuberculosis monaya ekgatat niah tbtb. - introduction - etiology & epidemiology -...

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