B313 - PULLORUM DISEASE

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B313 - PULLORUM DISEASE

Nature of the disease
Pullorum disease is the infection of poultry by Salmonella pullorum. The infection is very similar to condition caused by S. gallinarum.
Classification
OIE, List B disease
Susceptible species
Chicken and turkeys, S. pullorum is a specific bacteria but it can affect other bird species.
Distribution
Worldwide, nowadays it seems to be absent from the Pacific region. 
Clinical signs 
The incubation period is usually a few days. The disease affects almost exclusively young birds which exhibit:
  • Peracute infection with sudden death,
  • Acute infection in first few days:
    • Weakness, 
    • Somnolence,
    • Anorexia,
    • Poor growth,
    • Pasting of vent with chalky white excreta, 
    • Death.
  • In older birds:
    • Lethargy, 
    • Huddling under brooders, 
    • Wing droop,
    • Dyspnoea.
  • Growth retardation and poor feathering of survivors.
Post-mortem findings 
Gross lesions may be seen in chronic disease, but are usually absent in peracute disease. When present the following may be seen:
  • Enlargement and congestion of liver, spleen and kidneys,
  • Yolk sac retention, with yolk appearing creamy or caseous,.
  • Lung and heart may have white nodules, pericardium may be thickened, with yellow or fibrinous exudate,
  • Gastro-intestinal tract - may have white nodules on the gizzard, caeca, large intestinal wall.
  • Caseous cores may be seen in the caeca.
  • Joints may be swollen with yellow viscous fluid.
Differential diagnosis 
Specimens required for diagnosis 
Tissue and faeces samples can be submitted for bacteria identification through culture or genetic techniques.

Serological tests are satisfactory for establishing the presence and estimating the prevalence of infection within a flock.

Transmission   
From infected birds, their faeces and their eggs. Ingestion of contaminated food, water or bedding, and contact transmission; also mechanical spread by humans, wild birds, mammals, flies, and on trucks, feed sacks. May occur in newly-hatched birds due to trans-ovarial transmission.
Risk of introduction   
Pullorum could be introduced by importation of live infected chicken, hatching eggs. The bacteria can also be found in poultry meat but contamination of poultry flocks through this route is at low risk.
Control / vaccines  
Live and inactivated vaccines are available for fowl typhoid in some countries.

If introduced control should focus on eradication of the disease through isolation and destruction of contaminated flocks, proper disposal of carcasses and disinfection of fomites. 

References
  • Pullorum disease, In Merck Veterinary Manual, National Publishing Inc. Eight ed, 1998, Philadelphia, p. 1960-1962
  • Office International des Epizooties, 2002