Pullorum disease in Poultry

Pullorum disease is a highly contagious, egg-transmitted disease. It is mainly a blood infection of chickens.

The disease is characterized by white diarrhoea in young chicks.

Cause

A bacterium called Salmonella pullorum. Mortality from pullorum disease is usually confined to the first 2-3

weeks of age.

Spread

I. The most important method of spread is vertical transmission. That is. from an infected hen through

the eggs to the newly hatched chicks.

2. Such newly hatched chicks spread the infection to other chicks in hatcheries through their soft feathers which are heavily contaminated by S. pullorum.

3. Affected chicks shed S. pullorum through the faeces. This is the major method of spread among chicks.

4. Contaminated feed, water and litter can also be a source of S. pullorum infection.

5. Attendants, visitors, feed dealers, and chicken buyers who move from house to house and from farm to farm, may carry infection.

Symptoms

I. Pullorum disease is mainly a disease of chicks. It is seen in chicks below 3 weeks of age. The first

indication is usually a large number of dead-in-shell chicks, and deaths soon after hatching.

2. Affected chicks show depression with a tendency to crowd together in a small space, respiratory distress, loss of appetite and white thick and sticky droppings that adhere to the feathers around the vent. That is, white diarrhoea. The chicks breathe with difficulty and death may soon follow. The peak mortality usually occurs during the 2nd and 3rd week. Mortality varies greatly and in extreme cases can be 100%.

3. Older birds may appear depressed and have pale shrunken combs with ruffled feathers. Low egg

production may be the only symptom of the disease when adult birds are affected. The condition, however, is rare in adult birds.

Postmortem Findings

I. Chicks may have an inflamed, unabsorbed yolk sac. The lungs may be congested and the liver dark and

swollen with haemorrhages visible on surface.

2. Chicks that die after showing signs for I or 2 days show inflammation of the caeca. The caeca are enlarged and distended with hard, dry, necrotic (dead) material. Distinct, small, white, necrotic foci (area of dead tissue) are also usually found in the liver  lungs, heart, and gizzard wall.

3. In adult birds, the characteristic lesion is an abnormal ovary. The ova are irregular, cystic, deformed and

pedunculated (attached) with prominent thickened stalks. In some infected adult hens the ovary is inactive, the ova being small, pale and undeveloped.

Diagnosis

I. The symptoms and postmortem findings may vary and are not quite character istic to make a firm diagnosis.

The disease is diagnosed in the chick by isolating S. pullorum from liver or lungs.

2. Infection in older birds can be detected by demonstrating S. pullorum antibodies in blood samples by agglutination test.

Treatment

A number of antibiotics reduce the mortality.

Control

I. Test repeatedly the blood of breeding flocks (parents) and remove reactors. This must be combined with high management standards and hatchery discipline.

2. Replacement birds must be purchased only from flocks known to be free of the disease.

3. Eggs from pullorum-free flocks should be incubated and hatched only in hatcheries receiving eggs exclusively from clean flocks.