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