Paratyphoid disease :

       It is an important bacterial disease of chicken worldwide.

• Chicks from hatcheries are most at risk .

  When chicks are raised by mother hen ; a chick gets beneficial microflora by consuming some of its mother fecal material ,  but no option in hatcheries.

• Zoonotics disease

  Etiology :

      It is caused by one of many non-host-adapted Salmonella. S. enterica enteritidis

Transmission :

• Horizontally via contaminated environment or infected rodents
• Vertical transmission to progeny from infected breeders through contamination of egg shell
• Transovarial transmission ( salmonella can infect the interior of egg )

 Clinical signs :

• Lethargy
• Increased thirst
• Huddling near the source
• Pasty butt
• Swollen eye
• Swollen joints
• Droopy wings
• Decreased egg production
• Diarrhoea
• Cyanosis of comb and wattle

Postmortem finding :

Gross lesion:

a. Chicks :

• Focal or diffuse necrosis in liver
• Unabsorbed yolk sac

b. Adult :

• Splenomegaly
• Cu coloured enlarged liver with focal or diffuse area of necrosis
• Enteritis ( duodenum and jejunum )
• Pericardium may show milky fluid
• Infection occasionally localize in eye or synovial tissue

fig: Focal necrosis in liver

fig: unabsorbed yolk sacs

Microscopic lesions :

• SI : congestion and some mononuclear cell infiltration.
• Necrosis in the liver and heart with infiltration of heterophil and mononuclear cells.
• Necrosis of lymphocytes in lymphoid follicles of spleen.
• Lungs : reveal pneumonic lesions consisting of some heterophilic infiltration along with serous exudate

      Diagnosis :

• History
• Clinical sign and lesion
• Isolation and identification of bacteria
• Antibiotic sensitivity test
• Ag detection test
• Whole blood agglutination test

    DDx :

• Pasteurellosis : edema of combs and wattle , septicaemia , and bipolar staining organism
• Pullorum disease : chalk like diarrhoea , young chicks
• Coli-septicaemia : bronchopneumonia