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Bovine Tuberculosis Monaya Ekgatat NIAH TBTB. - Introduction - Etiology & Epidemiology - Clinical Signs - Post mortem lesions - Diagnosis - Public Health.

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Presentation on theme: "Bovine Tuberculosis Monaya Ekgatat NIAH TBTB. - Introduction - Etiology & Epidemiology - Clinical Signs - Post mortem lesions - Diagnosis - Public Health."— Presentation transcript:

1 Bovine Tuberculosis Monaya Ekgatat NIAH TBTB

2 - Introduction - Etiology & Epidemiology - Clinical Signs - Post mortem lesions - Diagnosis - Public Health - Prevention and control Bovine Tuberculosis NIAH

3 Zoonosishuman - 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 NIAH

4 Etiology and epidemiology Agents Mycobacterium tuberculosis (human) Mycobacterium bovis (animal) Mycobacterium avium (bird) NIAH

5 Mycobacterium tuberculosis complex (MTB. Complex) M. caprae M. tuberculosis M. caprae M. pinnipedii M. bovis M. pinnipedii M. africanum M. canetti M. microti Etiology and epidemiology

6 Mycobacterium bovis Can survive for several months in the environment (cold, dark and moist condition) o C survival time days Dry or moist soil (34 o C) : 4-8 weeks Summer : 4 days

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8 Maintenance hosts for M. bovis - cattle - buffalo Reservoir 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 NIAH

9 Badger

10 African buffalo Warthog

11 Common duiker Greater kudu

12 Brush-tail possum

13 Etiology and epidemiology Transmission Respiration----aerosal (short distance) Ingestion ( unpasteurized milk) Source of infectious bacteria - respiratory secretion - feces - milk - (urine) - vaginal secretion - semen NIAH

14 Incubation Period 3 weeks – years: under natural condition Morbidity and Mortality 1-2 animals = % infected = % developed gross lesions Severity - dose of agents - individual immunity Mortality : rare

15 Clinical Signs Chronic ( 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) NIAH

16 Post mortem lesions NIAH

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21 Lymphnodes: calcified

22 NIAH

23 Tubercles in liver

24 NIAH

25 Mesenteric lymph node

26 Diagnosis Clinical signs (lacking) Clinical signs (lacking) Laboratory diagnosis 1. Identification of the agent a) Microscopic examination b) Culture of M. bovis (3-6 weeks) - biochemical tests - culture characteristics c) Nucleic acid recognition methods NIAH

27 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

28 Presumptive 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

29 - 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 NIAH Differential Diagnosis

30 Laboratory Diagnosis 1. Identification and isolation of the agent NIAH

31 M. bovis: Cord Formation

32 NIAH M. bovis: granule in P&B

33 NIAH Immunohistochemistry

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35 NIAH DNA - hybridization

36 ELISA: Detection of MTB complex NIAH

37 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

38 Antigen:Bov. PPD 0.1 ml(not more than 0.2 ml) = 2,000 IU – 5,000 IU Work plan 0 h hrs 2.Tuberculin test 1 st measure injection 2 nd measure Negative reaction < 2 mm w/o local clinical signs Inconclusive reaction 2-4 mm w/o local clinical signs Positive reaction ≥ 4 mmwith or w/o local clinical signs (one fold + ≥ 8 mm) Retest: after days (cattle), 120 days (deer) NIAH

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40 Cervical Test

41 Caudal fold Test

42 Axillary Test

43 Base of the ear

44 Anywhere

45 Tuberculin test NIAH

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47 Positive reaction

48 NIAH Tuberculin test at cervical

49 NIAH

50 Deer: Tuberculin test (cervical)

51 NIAH

52 a) Gamma-interferon assay (IFN) a) Gamma-interferon assay (IFN) – early detection NIAH 3. Blood-based laboratory tests

53 NIAH

54 IFN Assay

55 b) Lymphocyte proliferation assay Antigen : PPD-Bov, PPD-Avi Not used for routine diagnosis - long incubation times - use of radio-active nucleotides Expensive

56 NIAH c) ELISA: complementary test

57 d) Chromatographic Immunoassay

58 Chromatographic Immunoassay

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60 Samples 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

61 Public Health Due to M. bovis : very rare Asymptomatic Localized: lymph nodes, skin, bones and joints, genitourinary system, meninges or respiratory system

62 Prevention and Control Sanitary 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) NIAH

63 -Quarantine measures -Slaughter inspection surveillance and trace - back -Surveillance in other animals -Pasteurisation of milk Medical Prophylaxis No chemophophylaxis or treatment Prevention and Control NIAH

64 Control Test-and-slaughter (domestic animals) Test-and-segregation Affected Herds - re-tested periodically

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66 Thank you for your attention


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