Diagnosis of bovine tuberculosis in Mozambique

Comparison of diagnostic methods

1Maxhuza, G., 2Adelina Machado, A., 3Manfred Tanner,4Irmgard Moser 1National Department of Veterinary Services, Ministry of Agriculture, Maputo, Mozambique

2Veterinary Faculty, Eduardo Mondlane University, Maputo, Mozambique 3Institute of Infectious diseases and Zoonoses, Ludwig-Maximilian-University, Munich, Germany

4Friedrich-Loeffler-Institut, Institute of Molecular Pathogenesis, Jena, Germany

VI International M.bovis Conference

16th - 19th June 2014

Cathays Park, Cardiff, Wales, CF10 3ND, Great Britain

Tuberculosis (bTB) prevalence in cattle

Morrumbala 12% bTb

Govuro 60% bTb

Massingir 1% bTb

Manifestation of tuberculosis and immune response in cattle

Imm

une R

esp

onse

Time

Cellular Immunity Humoral Immunity

Anerg

y

Bacterial Load

Pathology

Visible Lesions

γ-IFN

Tuberkulin-Test

Modified according to

de la Rua-Domenech et al., 2006

Symptoms

Non Visible Lesions

A Positive herd 106 animals 69/89 SICCT positive

B Positive herd 80 animals 28 SICCT positive

C „Negative“ herd 100 animals 9 SICCT positive

Animals and testing methods

Single interdermal cervical comparative tuberculin test (SICCT)

Gamma interferon release assay (IFN γ; Bovigam®)

ELISA (IDEXX M. bovis Ab Test; IDEXX®)

Meat inspection

Bacteriological culture

Molecular identification of isolates (PCR)

IFNƴ SICTT Culture Inspection IDEXX

SICTT IFNƴ

SICTT Inspection

SICTT IDEXX

Inspection IDEXX

1 2 3 4 5 2 1 2 4 2 5 4 5

1 IFNγ

2 SICCT

3 Culture

4 Inspection

5 IDEXX

Synopsis of the results of

diagnostic procedures in herd A

106 animals tested

positive

not tested

inconclusive

negative

BTB Detection methods – Comparison of results

Animals positive / Animals tested

Method IFN γ SICCT Meat inspection Culture IDEXX

N 28/103 14/103 ? 69/89 88/94 31/41 29/75

% 27.2 13.6 77.5 93.6 75.6 38.6

SICCT Meat N %

insp..

+ + 61 74.4

- + 13 15.8

? + 4 4.8

+ - 3 3.7

- - 1 1.3

Total 82 100.0

SICCT IDEXX N %

+ + 22 34.9

+ - 24 38.1

- + 3 4.8

- - 8 12.7

+ ? 3 4.8

- ? 2 3.2

? - 1 1.5

Total 63 100.0

Meat IDEXX N %

insp.

+ + 28 41.2

+ - 30 44.2

- - 5 7.3

+ ? 5 7.3

Total 68 100.0

5/75 ?

6.6

SICCT IFNγ N %

+ + 24 27.9

+ ? 10 11.6

- + 1 1.2

+ - 35 40.7

Total 86 100.0

IFNγ and IDEXX results interpretation

A/P>0.3 Positive

A/P<0.3 Negative

A : Sample

P: Positive Control

OD values of positive samples

1,005814

5,478405

3,773256

OD values of negative samples

-0,02492

-0,03654

-0,02907

OD values of inconclusive samples

0,121262

0,20515

Positive OD PPDbov – NIL antigen > 0.1 and

OD PPDbov – PPDav > 0.1

Negative OD PPDbov – NIL antigen < 0.1 or

OD PPDbov – PPDav < 0.1

Inconclusive OD PPDbov – NIL antigen > 0.1 and

OD PPDbov – PPDav > 0.05

Active cells OD PWM – NIL antigen > 0.5

Active cells OD PWM – NIL antigen > 0.3

Routine

Masseter muscle

Tongue

Lungs

Liver

Spleen

Lymph nodes

Prescapular

Mediastinal

Bronchial

Precrural

Mesenterial

Inspection of the inner and

outer wall of the carcass

Additionally for research

Kidney

Lymph nodes

Tonsils

retropharyngeal

parotidic

Meat inspection

Score of lesions (herd A)

53 Bronchial Ln.

49 Mesenterial Ln.

47 Mediastinal Ln.

34 Retropharyngeal Ln.

34 Lungs

30 Liver

13 Tonsils

13 Prescapular Ln.

10 Submandibular Ln.

9 Spleen

6 Mandibular Ln.

5 Parotidic Ln.

4 Diaphragma

3 Precrural Ln.

2 Kidney

2 Intercostal Ln.

1 Pleura/Percard

Pathological lesion at meat inspection

Summary and conclusion

Four diagnostic methods to detect bTb in a highly infected cattle herd have been compared:

Single interdermal cervical comparative tuberculin test (SICCT)

Gamma interferon release assay (IFN γ; Bovigam®)

ELISA (IDEXX M. bovis Ab Test; IDEXX®)

Meat inspection

SICCT and meat inspection yielded the highest detection rate with 77.5% and 93.6%,

respectively, and the highest single animal agreement with 77.4%.

IGRA yielded the lowest detection rate with only 27.2% , 40.8% with „severe“ interpretation.

IDEXX ELISA yielded a detection rate of 38.6%, 45.2% with „severe“ interpretation.

Bacteriological culture yielded a detection rate of 75.6%. However, the species identification

of the isolates has not yet been done.

From the diagnostic methods for intra vitam diagnosis of bTb SICCT yielded by far the highest

detection rate.

Tuberculin skin testing – rough conditions

Tuberculin skin testing – using a mobile crush barrier

Many helpful hands available

Tables for veterinary equipment

and documentation

Tuberculin skin testing – normal procedure

Tuberculin skin testing – normal procedure (cont.)

Tuberculin skin testing – rough conditions

Tuberculin skin testing – rough conditions (cont.)

Capturing escaped cows for testing

Tuberculin skin testing - Measuring skin fold thickness

Tuberculin skin testing - Injecting PPDs and harvesting blood

Positive skin test reactions

Accommodation in the field

Lab Appartments

back home

from the field

Friendly contacts

at the water supply

Lab work in the field – and in Maputo

Border control

On the way to Malawi having negotiations

Crossing

the border

Walking towards Rio Chire

Fans and audients everywhere

Thank you for your attention!

Obrigada pela vossa atenção!

Bem Vindo Mocambique!