Poultry Salmonella Pullorum

Salmonella pullorum infection is an infectious, egg-transmitted disease affecting chicks and turkey poults. This disease is often associated with white diarrhea and high mortality in young birds, whereas adults are non-symptomatic carriers of infection. This disease has also been known as bacillary white diarrhea or pullorum disease.

Salmonella pullorum is a Gram-negative, rod-shaped bacterium that is usually poultry-specific and is closely related to Salmonella gallinarum, the causative agent of fowl typhoid. These two bacteria share surface antigens and the pullorum test can be used to identify reactors to both pullorum disease and fowl typhoid.

Young chicks and turkey poults are particularly affected and infection is often fatal. Older birds are more resistant and may not show clinical signs or may serve as inapparent carriers, but can transmit this infection through the egg to the hatchling. Infected hatchlings can also transmit the infection horizontally to other birds in the hatcher.

Because egg-transmittion can occur, the concern for backyard flocks is that infected hens lay infected eggs, which hatch to produce infected chicks. Infected chicks that survive can later on lay infected eggs to repeat the cycle. Hence, this disease is of concern for farmers hatching their own breeding stock.

Peak mortality occurs about 2–3 weeks after hatching and can begin prior to 10 days of age.


Clinical Signs

In young birds:

• anorexia
• depression
• diarrhea
• dying or death (highest mortality rate in the first 2 weeks of life and in incubators); and
• laboured breathing.

In growing and mature birds:

• anorexia
• decreased egg production
• depression
• diarrhea
• high fever
• increased mortality (usually higher in chickens than turkeys); and
• poor hatchability.

In severe cases, dead chicks can be found in the brooder. Pasty white vents (cloaca) are noted in affected birds which appear chilled and are reluctant to feed.

Adult birds that are necropsied occasionally have misshapen ovaries, pericarditis, and peritonitis, but some have no lesions. Young birds may have no gross lesions if the infection is peracute.

White to gray nodules in the heart, liver, cecum, and gizzard may be seen. Moreover, cecal plugs, firm, caseous, yellow cores found in the lumen of the cecum, are characteristic of this disease.

Birds may also have septicemia with hepatosplenomegaly (hepatitis).


Diagnosis

Bacterial culture of samples from dead birds and/or blood testing (whole blood plate test) from live birds is needed for a definitive diagnosis.

Differential diagnosis should include fowl typhoid, colibacillosis, chilling or overheating associated with white diarrhea, omphalitis (navel infection) caused by Escherichia coli, Pseudomonas, or Staphylococcus.


Treatment

Treatment of infected flocks will not alleviate the perpetuation of the carrier state and is never recommended.

Amoxycillin, potentiated sulponamide, tetracylines, fluoroquinolones may be used to manage the course of the disease.

Control is based on strict biosecurity measures put in place to prevent the introduction of infection into the flock.