Salmonellosis
|
Synonyms – Paratyphoid
-
Salmonellosis occurs in all animals but is more common in cattle (S. Dublin, S. typhimurium), horses (S. typhimurium) pigs (S. choleraesuis, S. typhimurium). It is rare in dogs and cats
Transmission
- Direct or indirect
- Contamination of feed, water and environment
- Ingestion of materials contaminated with faeces
- Carrier animals
Pathogenesis
- Entry of bacteria
- Adhere to intestinal epithelial cells by fimbriae or pili
- Invasion of epithelial cells are controlled by invasion genes in bacteria induced by low oxygen tension in intestine
- Attaches to intestinal cells
- Proliferate within enterocytes and macrophages
- Macrophages transport bacteria to lymphnodes
- Growth of bacteria within macrophages is aided by bacterial genes induced by acidic pH within macrophage phagolysosomes
- Multiplication occurs
- Infection ranges from mild enteritis or septicemia
Clinical signs
-
Septicaemia
- Characteristic form in new born foal, calves and guinea pigs
- Depression, dullness, prostration, high fever (105˚ – 107˚)
- Death within 24 – 48 hrs
-
-
Chronic enteritis
-
Common syndrome in pigs, cattle, horses
-
Persistent diarrhoea with passage of spots of blood, mucus, fibrinous casts; moderate fever. Loss of weight – emaciation
Lesions
-
Enterocolitis – Hyperaemia, thickening, hemorrhages in the mucosa of ileum and colon ulcerations
-
Microscopical lesions – Haemorrhage, oedema, necrosis, leucocytic infiltration
-
Multiple necrotic foci in liver, presence of paratyphoid nodules (Small aggregation of reticulo – endothelial cells)
-
Enlargement of spleen and lymphnodes – Hyperplasia of reticulo endothelial cells
-
Septicaemia – fibrinoid necrosis of vessel walls and hyaline in glomerular capillaries
-
Ulcerative proctitis
-
Abortion – occurs late in gestation; Oedematous placenta with focal haemorrhage and necrosis; oedema of foetus
Diagnosis
|
Last modified: Wednesday, 21 March 2012, 11:31 AM
Participants