Pullorum disease

• The historical name is bacillary white diarrhoea.
• Pullorum disease is characterized by very high fever in young chicken and turkeys. Affected birds huddle near the heat source, they are anorectic, weak , depressed , and have white fecal material pasted in the vent area.
• Birds may have respiratory disease, blindness or swollen joints.

Etiology:

                 Salmonella enterica Pullorum   usually causes mortality in young chicken and turkeys within the first 2-3 weeks of age and also affects other chickens and domestic fowl.

• Salmonella : Rod-shaped, Gram-negative, Facultative anaerobic, Non-spore-forming

                  It belongs to the same family as Escherichia, which includes the species E.coli.

Transmission :

• Vertical ( transovarial) but also occurs via direct or indirect contact with infected birds ( respiratory or fecal)
• Through contaminated fed , water , or litter
• Egg or hatchery infection
• Transmission between farm is due to poor biosecurity

Pathogenesis :

  Infection with high or infective   dose of S. pullorum via oral route

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Bacteria invades digestive epithelia ; irritation and causes diarrhoea

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                           Ultimately enters into blood causing bacteremia.

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 Bacteria seeded into cells and tissues of different organs (liver, lung, spleen, kidney  , different parts of the reproductive tract of hens and testes of male ) causing pathological lesions.

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The bacteria invade ovary and egg follicle and transmit into laid eggs then to hatched  chicks.

 Lesions:

1.     Gross lesion  :

• No lesions occur in acute cases due to septicaemia and death.
• Gross lesions in adults are not generally seen.
• Lesions in young  include :
• Unabsorbed  yolk sac.
• Classic grey nodules in liver , spleen , lungs, heart , gizzard , intestine , etc .
• Synovitis
• Gross lesions in adults are not generally seen .
• Deformed ova with atrophic follicles.
• Pericarditis
• Articular and peri articular swelling of hock and wing joint ( arthritis)
• Tumor like lesion in gizzard and heart

Fig: misshapen ovaries with atrophic follicles.

Fig : granulomatous hepatitis( small necrotic foci )

Fig: granulomatous lesion in spleen(raised white spot)

Fig : granulomatous lesion in ovary ( oophoritis)

2. Microscopic lesion:

• firm, cheesy material in the caeca ( caecal core ) and raised plague in the mucosa of lower intestine .
• nodular pericarditis
• Fibrinous peritonitis or haemorrhagic  
• Regressing   ovarian follicle with caesous content.
• Chronic infection produces lesions indistinguishable from those of fowl typhoid.

Clinical   sign :

• Droopiness
• ruffled feather
• chilled appearance with birds huddling near source of heat
• labored  breathing or respiration distress
• presence of white diarrhoea pasted  around the vent known as “pasted vent”.
• Pot bellied
• Loss of appetite
• Depression
• Pale shrunken comb
• Low egg production

Diagnosis :

• History
• Clinical signs and lesions
• Postmortem finding
• Isolation and identification of bacteria