Avian Tuberculosis (TB) in Laying H ...

Avian Tuberculosis (TB) in Laying Hens

Avian Tuberculosis (TB) in Laying Hens

Avian Tuberculosis is diagnosed rarely in commercial poultry. It has been diagnosed in small flocks and in relatively small free-range commercial flocks.

Avian Tuberculosis (TB) is a contagious disease and chronic infection. Persistence in a flock, once established, induces unthriftiness and finally causes death. Clinical signs are not pathognomonic. In advanced infections, the bird will live for a shorter period of time than its pen mates, so it may trigger them fatigue easily and possible depression. Although appetite usually remains good, progressive and striking loss of weight commonly occurs. Feathers assume dull and ruffled appearances. Comb, wattles and earlobes often appear pale and thinner than normal and have a dry epidermis. Occasionally, the comb and wattles have a bluish discolouration. In many instances, the bird reveals a unilateral lameness and walks with a peculiar jerky hopping gait. Paralysis from tuberculous arthritis can sometimes occur. There is often persistent diarrhea with soiling of the tail feathers. Avian tuberculosis appears to be less prevalent in younger birds.

Observed Clinical Signs Happenings

Clinical signs are not pathognomonic

Visibly sick birds

  • Few visibly sick birds
  • Comb, wattle and earlobes often appear pale and thinner than normal and have dry epidermis
  • The face of affected birds appears smaller than normal
  • Birds will be less lively than its pen mates
  • Birds will fatigue easily
  • Birds may be depressed
  • Birds will fatigue easily
  • Some may adopt a sitting position
  • Progressive and striking loss of weight commonly occurs
  • Atrophy of breast muscles with the prominent keel
  • One group within the flock had good body condition continued to lay eggs. Another group within the same flock was emaciated, did no lay eggs.

Mortality

  • Low mortality or increases gradually
  • Affected birds may die within a few months  or live for many depending on the severity or extent  of the disease
  • Sporadic deaths

Dead Birds

  • Poor body fleshing condition
  • Occasionally, birds may die suddenly in good bodily condition

Dropping

  • Often there is persistent diarrhea with soiling of the tail feathers
  • Intestinal nodules may be ulcerative, resulting in severe diarrhea
  • Diarrhea with soiling of the tail feathers
  • Soiled vent feathers or pasty droppings
  • Feces smeared on feathers around the vent

Head Comb Wattles Face Nostrils Sinuses Mount Beak Earlobes

  • Comb, wattle and earlobes often appear pale and thinner than normal and have dry epidermis
  • Occasionally, the comb and wattles have a bluish discolouration
  •  Icterus of the comb and wattles is an indicative of advance hepatic damage may be noted
  • One group within the flock had good body condition continued to lay eggs. Another group within the same flock was emaciated, did no lay eggs.

Body Parts (Neck wings breast abdomen shanks legs hocks feet joints vent skin)

  • Atrophy of breast muscles with a prominent keel
  • Progressive and striking loss of weight commonly occurs
  • Atrophy of breast muscles with the prominent keel
  • Loss weight commonly occurs

Lameness or unusual movement, incoordination, ataxia

  • In many instances, the birds reveal and unilateral lameness
  • The birds walk with a peculiar jerky hopping gait
  • Paralysis from tuberculous arthritis can sometimes occur

Feather Abnormalities

  • Feathers assume a dull and ruffled appearance
  • Diarrhea with soiling of the tail feathers
  • Soiled vent feathers or pasty droppings
  • Feces smeared on feathers around the vent
  • Dirty or Pasty vents or feathers with droppings around the vent

Avian Tuberculosis (TB) in Laying Hens DOES NOT exhibit or manifest any of the following clinical signs happenings:

  1. Egg drop
  2. High mortality or increases rapidly
  3. Many visibly sick birds
  4. Flock behaviour activity change
  5. Respiratory abnormalities
  6. Eyes abnormalities
  7. Neurological Nervous
  8. Feed Consumption Changes
  9. Diet or Feed Changes (Recent Feed delivery, Recent formulation /diet, Other silo or improper storage, Another feed brand)
  10. Shell quality defects
  11. Internal Egg defects
Causing Agents
Bacterial Infection. Mycobacterium avium serovars 1,2 and 3. Mycobacterium avium serovar 2, the organism most frequently isolated from chickens is rarely isolated from humans.
Affected Systems/Organs
Digestive and Locomotor System. Various organs and tissues. Bones and joints.
Spread
Transmission bird to bird. Droppings. Objects or items contaminated with droppings.
Mainly Affects
Liveability.
Solution
Quarantine. Biosecurity, Hygiene. Disinfection and anything that might be contaminated by their excretions or faeces.
Suggested Actions
  • Can be confirmed with clinical signs and gross lesions
  • Technical assistance recommended
  • Diagnosis should be confirmed with rapid assays and/or a certified laboratory
  • Veterinary intervention is recommended
  • Can be managed with vaccination programs.
  • This is a notifiable disease, veterinary intervention is essential. It is advisable that you run DTECT again to ensure you have answered all the questions correctly. If you suspect that you may have this disease please contact your local authorities immediately.

Impact on Egg quality

0

Impact on Liveability

3


Impact on Production

0

Overall Economic Impact

4



Y.M. Saif.2008.Disease of Poultry. 12th Edition. page 944

David E. Swayne. 2013. Diseases of Poultry 13th Edition. page 1012

Mark Pattison, Paul F. McMullin, Janet M. Bradbury. Dennis J. Alexander. 2008. Poultry Diseases. 6th Edition. 252

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