Fowl paratyphoid is caused by Salmonella typhimurium. Organism is motile, Gram negative, Ubiquitous in distribution, Stable in environment, Remain in feed and water for weeks.
- Young chicks are highly susceptible leading to serious illness and death. Older birds are less susceptible without significant morbidity and mortality.
- Environmental and management factors influence susceptibility.
- Exposure to stressful conditions facilitates salmonella infection. E.g. lowering of brooder temperature by 5º to 8º C increases mortality.
- Spread through vertical and horizontal transmission but not a true vertically transmitted disease.
- Infection carried on egg by Faecal contamination or nest-box dust.
- Lateral spread by direct contact, contaminated feed and water.
- Contaminated feedstuff mainly animal protein in ration like bone meal, meat meal, fish meal, etc.
- Biological vectors like insects, cockroach, mealworm, rats, mice etc. help in transmission.
- Three categories of toxins are released by PT salmonellae: Endotoxin associated with lipid it produces fever, causes liver and spleen lesions. Enterotoxins (heat labile) induce a secretory response in epithilial cells leading to fluid accumulation in intestine. Cytotoxin (heat stable) cause structure damage to intestinal epithelium by inhibiting protein synthesis.
For more details please download the attachment- PPT.
