Salmonellosis
fibrinous peritonitis
The gram negative rod shaped bacteria common in poultry are
Salmonella pullorum
Salmonella gallinarum
Salmonella typhimurium
1.1 Pullorum Disease Causative agent – Salmonella pullorum. Incidence and distribution- Chickens all over the world. Transmission
Vertically through hatching eggs.
Horizontal through litter, feed and water.
Signs
whitish milliary necrosis liver
High mortality in chicks below 3 weeks of age.
Excessive numbers of embryos dead in shell.
Chick death shortly after hatching.
Tendency to huddle.
Respiratory distress.
Loss of appetite
Soiled vent with white viscous droppings.
Occasionally swollen joints.
Dropped egg production in layers.
Gross Lesions Chicks
Sudden mortality
Peritonitis with inflamed, unabsorbed yolk sac.
urates inn ureters
Liver enlarged and congested .
Congested or anemic kidneys with distended ureters.
Yolk sac contents filled with yellowish or creamy caseous material.
Enlarged spleen.
Lungs may be congested.
Caeca are enlarged and distended with casts of hard, dry necrotic material.
Layers
Ovaries irregular, misshapen, cystic, discoloured and pedunculated with prominent thickness and stalks.
Occasionally peritonitis arthritis and pericarditis.
Abdominal peritonitis, arthritis and pericarditis.
Discrete small white necrotic focl are often found in liver.
spleenomegaly
Histopathology
Degenerative changes and necrosis of liver parenchyma with infiltration of mononuclear cells.
Degenerative changes and focal necrotic areas of liver parenchyma with congestion and haemorrhages.
Diagnosis
Confirmative diagnosis by isolation and identification of S. pullorum.
Serology by rapid plate agglutination test.
1.2 Fowl Typhoid
Causative agent – Salmonella gallinarum. Incidence and distribution – distributed all over the world in chicken, also reported in ducks, pheasants, guined fowl, goose and quails. Transmission
Through water, feed, wild birds, animals, files, unsterllised fish and meat meals.
It can be transmitted vertically.
Signs
Increased mortality
Reduced feed consumption.
Drop in egg production.
Watery mucoid yellowish diarrhea.
Pale combs.
Gross Lesions
The most consistent finding is swollen fragile liver with dark red or almost black colour and the surface has distinctive coppery bronze sheen.
In subacute or chronic stage-greenish brown or bronze colour swollen liver.
Occasionally Milliary type grayish white foci are seen in the liver and myocardium
Misshapen and discoloured ova.
Enlarged spleen.
Catarrhal inflammation of intestine.
Dark brown bone marrow is the characteristic feature of this disease.
Diagnosis
The organism can be isolated from affected visceral organs.
PARATYPHOID INFECTION
Paratyphoid Infection
Causative agent – Salmonella typhimurium
Transmission
Humans, rhodents, wild birds, insects, pigeons, water and feed are the sources of infection.
Signs
Affected birds are depressed, reluctant to move, have ruffled feathers and drooped wings.
Diarrhoea with pasting of vent.
Gross Lesions
caeca are filled with gelatinous
Visible lesions are not a must but one can see septlcaemic carcass with swollen liver, spleen, lungs and kidneys.
Inflamed unabsorbed yolk sac is a common feature.
The most characteristic feature is typhilltis.
Caeca distended with hard white necrotic cores.
Septicaemia, pericarditis and perihepatitis.
Histopathology
Congestion, haemorrhages, infiltration of mononuclear cells with degenerative changes and focal areas of necrosis in liver.
Catarrhal enteritts with inflammatory cells and necrosis.
Degenerative changes and focal areas of necrosis with hyperemia and presence of a few inflammatory cells in heart.
Diagnosis
Confirmation by isolation and identification of causative agent
Liver, gall bladder, yolksac, intestines, caecal contents are the best sit
es
for isolation of the organism
