118. Fowl tuberculosis.

Question 1

Occurrence of Fowl tuberculosis?

Answer 1

Occurrence:

• Backyard poultry,
• zoo animals,
• wildlife park

Question 2

Aetiology of fowl tuberculosis?

Answer 2

Aetiology – M. avium-complex

• M. avium subsp. avium:
• resistance (soil); old hens, pheasant, water fowl
• M. tuberculosis: cage birds, parrot (see above)
• M. avium subsp. silvaticum: wild living birds

Question 3

Epidemiology?

Answer 3

Epidemiology:

• Chronic disease,
• extremely resistant; shed in faeces (long survival in the environment >1y),
• indirect transmission (food, water etc.),
• old birds (parks, zoo, free living)

Question 4

Pathogenesis?

Answer 4

Pathogenesis:

• PO infection → gut, lymphoid patches →
• blood → always generalisation (no local form – b/c
• no LNs in birds & primary complex will not form);
• repeatedly gets into the blood (repeated generalisation)

Question 5

Clinical signs?

Answer 5

Clinical signs:

Not very informative, chronic disease (always adult animals)

• weight loss
• anaemia
• drop of egg production

Organic signs

• gut: diarrhoea
• liver: jaundice
• lungs: respiratory signs
• bones, joints: lame, limping

Question 6

Pathology?

Answer 6

Pathology:

• Very informative & typical:
• Weight loss,
• anaemia,
• tuberclues (liver, spleen, gut, bones etc. –
• different size of tubercles due to repeated generalisation so the age of the tubercles differ)

Question 7

Diagnosis of fowl tuberculosis?

Answer 7

Diagnosis

• Epidemiology - clinical signs - PM lesions
• Histology – reliable!
• Detection of the bacterium: Z-N staining (nest form of the bacteria), isolation, PCR
• Detection of the immune response:
• Tuberculin test (?): wattle enlarged & painful, 36-48 hours after injection, not reliable
• Cellular tests
• Detection of antibodies: there is always a generalisation - plate agglutination (stained
• antigen),
• ELISA – can get false negative reaction so repeat a week later

Question 8

Prevention, control?

Answer 8

Prevention, control

• There is no treatment, Prevention of infection
• Vaccine: M. avium subsp. avium, M. intacellulare: not effective
• Stamping out
• Soil remains infected - Don’t keep old birds (after the laying period then get rid of them)
• Prevention ʹ closed keeping, limited life span
• Eradication ʹ zoo, generation shift