Fowl typhoid

Fowl typhoid is disease of poultry caused by Salmonella gallinarum. The disease causes high mortality and it is very similar to Pullorum disease.

Susceptible species

Chicken and turkeys but it can be seen in other birds, however S. gallinarum is host specific.

Distribution

Widely distributed, however it is not present in the Pacific Region.

Clinical signs

In young chicks there is a per acute infection with sudden death, or and acute infection :

• Weakness,
• Somnolence,
• Anorexia,
• Poor growth,
• Pasting of vent with chalky white excreta
• Death in up to 90% of the cases.

In birds older than three weeks:

• Lethargy,
• Huddling under brooders,
• Wing droop
• Dyspnoea,
• Poor feathering of survivors.
• Decreased egg production

Post-mortem findings

• Liver, spleen and kidneys may be enlarged and congested,
• Yolk sac retention may occur, 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

• Pullorum disease
• Fowl Cholera
• Erysipelas

Specimens required for diagnosis

Tissue and feces 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 etc.

May occur in newly-hatched birds due to trans-ovarial transmission.

Risk of introduction

Fowl typhoid 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

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