36. 37. Pullorum disease is an acute systemic disease in chickens and turkey poults. The infection is trans-mitted with eggs and is commonly characterized by a white diarrhoea and high death rate, whereas adult birds are asymptomatic earners. The morbidity and the mortality rates increase about the 7th - 10th day after hatching. The affected chickens appear somnolent, depressed and their growth is retarded. The feathers around the vent in many chickens is stained with diarrhoeic faeces or pasted with dry faeces.

38. The oedema of tibiotarsal joints is a frequent associated sign. Pullorum disease is widely distributed among all age groups of chickens and turkeys. The highest losses are in birds under the age of 4 weeks.

39. 40. The aetiological agent is S. pullorum, a non-motile Gram-negative microorganism. S. pullorum is very resistant under moderate climatic conditions and could survive for months. It could be killed by fumigation with formaldehyde of breeder eggs in the hatchery. Typical for this form are the greyish-whitish nodes in one or some of the following places: heart (39), lungs, liver, gizzard walls (40) and intestines, the peritoneum.

Sometimes, greyish-whitish milliary necroses are found out in the liver. S. pullorum is transmitted by infected eggs of layer hens that are carriers. Many hatched infected chickens spread the microorganism by a horizontal route to other birds via the gastrointestinal and the urinary tracts. Adult carrier birds also spread the agent through their excreta.

42. Ureters are often filled with urates. For confirmation of the diagnosis, 5. pullorum should be isolated and typed. Pullorum disease must be differentiated from other salmonelloses, E. coli infections, Aspergillus that produces similar pulmonary lesions. Staphylococcus aureus, causing arthrites etc. Sometimes, the pulmonary nodes resemble the tumours in Marek's disease.

43. Acute fowl typhoid. The outbreaks usually begin with a sharp decline in forage consumption and egg production. The fertilization and hatchability rates are considerably reduced. Diarrhoea appears. The death rate in acute fowl typhoid is high and varies between 10% and 90%. About 1/3 of chickens hatched from eggs from typhoid-infected flocks die. A characteristic lesion for acute fowl typhoid in adult birds is the enlarged and bronze greenish tint of liver.

. 44. . Acute fowl typhoid. In some instances, the enlarged liver is mottled with multiple milliary necroses. The outbreaks are observed primarily in hens and turkeys, but the disease is sometimes encountered in other domestic or wild fowl.

45. Acute fowl typhoid. In other cases, the size of liver necroses varies from milliary to spots with a diameter of 1 - 2 cm. Unlike pullorum disease, fowl typhoid is lasting for months.

46. Acute fowl typhoid. The spleen is 2-3 times bigger, sometimes with greyish-whitish nodules prominating on the surface, representing hyperplasic follicles.

47. Acute fowl typhoid. Often, enteritis, especially of the anterior part of small intestine, sometimes with ulcerations, is present. The aetiological agent is Salmonella gallinarum. This organism usually shares common antigens with 5. pullorum and the two microorganisms often give a cross-agglutination reaction.

48. Acute fowl typhoid. More rarely, myocardial necroses due to Salmonella toxins are detected. The transmission of the infection by contaminated eggs is especially important. Moreover, the transmission of 5. gallinarum occurs mainly among growing or productive flocks and the death rate among adult birds is higher.

49. Acute fowl typhoid. The lungs acquire a characteristic brown colour. Here, necroses and, following their organization, „sarcoma-like nodules"

50. Chronic fowl typhoid. The lesions are primarily in the gonads. The ovaries are affected by inflammatory and degenerative changes.

51 Chronic fowl typhoid. Frequently, affected follicles are deformed and appear like thick pendulating masses. Fowl typhoid should be differentiated from other salmonelloses, E. coli infections, Pasteurella spp. infections etc. If breeder flocks are proved to be carriers of the infection, their eggs should not be used for breeding.

52. Chronic fowl typhoid. Sometimes, the going out of yolk from degenerated follicles results in fibrinous adhesive peritonitis. Taking into consideration that chemotherapy does not eliminate the carriership, the treatment of poultry infected with fowl typhoid or pullorum disease is not justified and is never recommended.