61. Infectious bronchitis of chicken, coronaviral enteritis of turkey.

Question 1

Infectious bronchitis History?

Answer 1

Infectious Bronchitis

Domestic fowl (chicken), pheasant (different but closely related virus)

History

• 1931 first description of disease
• Present worldwide
• Domestic fowl, pheasant, grey partridge, guinea fowl, peacock
• Pheasant CoC: only pheasant

Question 2

Epidemiology of Infectious bronchitis?

Answer 2

Epidemiology

• 4 structural protein
• Embryonated egg: allantois, trachea
• Many serotypes and genotypes: VN, HA and HAI after phospholipase treatment, MAb, S1 sequences
• USA strain in Massachusetts, Italy

Question 3

Transmission of Infectious bronchitis?

Answer 3

Transmission

• Infected, shedding animals, contaminated equipment
• No vertical transmission, eggs are not infected
• On surface of egg shell: inactivated within 5-6 days at hatchery
• From respiratory tract up to 1 month
• Faeces/urine up to 3-4 months
• Rapid spread
• High morbidity
• Mortality depends on age, environment, coinfections (infectious bursitis, E. coli, Ornithobacterium rhinotracheale, dust,

ammonium)

• No cross protection, short maternal immunity

Question 4

Pathogenesis of Infectious bronchitis?

Answer 4

Pathogenesis

1. Viral intake: PO, nasal
2. Viral replication: trachea, bronchus ➝ inflammation with degeneration, sera exudation
3. Viraemia: liver, kidney, ovary, oviducts, testicles

‣ Depends on organ tropism and age

‣ Below 6 weeks: permanent oviduct damage

‣ Grower: transient damage ➝ can be recovered by laying period

‣ Layer: transient damage ➝ drop in egg production (enervation, inappetence), egg shell malformation

‣ Nephropathogen: nephritis/nephrosis, arthritis

Question 5

IBV Under 6 weeks old Infectious bronchitis?

Answer 5

IBV Under 6 weeks old

• Clinical signs

‣ Incubation: 18-36 h

‣ Chickens are depressed and huddle under heat source

‣ Respiratory signs: gasping, coughing, tracheal rales, nasal discharge

• Pathology

‣ Serous, catarrhal or caseous exudates in trachea, nasal passages and sinusitis

‣ Cloudy air sacs which may contain yellow caseous exudates

‣ Caseous plug may be found in trachea

‣ Pneumonia

‣ Degeneration of ovary and swollen oviducts

Question 6

Nephropathogen strain?

Answer 6

Nephropathogen strain

• Clinical signs

‣ Incubation: 4-6 days

‣ Mild respiratory signs

‣ Depression, ruffled feathers

‣ Increased water intake, wet litter

‣ Increasing mortality

• Pathology

‣ Swollen, pale kidneys with broad septa

‣Kidney tubules and ureters contain irate crystals

‣ Nephritis histopathologically

Question 7

Growing chciken IB?

Answer 7

Growing chicken

• Mild respiratory signs
• Decrease in weight gain
• Temporary damage to oviduct

Question 8

Layer IB clinical signs and pathology?

Answer 8

Layer

• Clinical signs

‣ Mild respiratory signs

‣ Depression, loss of appetite

‣ Lobe is swollen

‣ Drop in production, increased number of poor quality eggs

‣ Production often does not return to pre-infection levels

‣ Hatchability may be negatively affected

‣ External and internal quality of eggs may be affected, resulting in misshaped or soft-shelled eggs with watery

content

• Pathology

‣ Egg peritonitis

‣ Degeneration of ovary

‣ Swollen oviducts

Question 9

Diagnosis and prevention of Infectious bronchitis?

Answer 9

Diagnosis

• IF, ELISA, VN, PCR, HAG
• CAM: kills embryo, dwarfing
• Differentiation: NDV, ILTV, EDS

Prevention: Vaccines

• Attenuated ➝ aerosol, drinking combined
• Inactivated ➝ combined with NDV, IBDV, EDS
• Cross-protection within serotype

Question 10

Turkey Coronavirus Enteritis ethiology and pathogenesis?

Answer 10

Turkey Coronavirus Enteritis (TCoV)

• Turkey transmissible enteritis, Blue comb, Mud fever

Etiology

• 1940 USA
• 1970 GB, India, Australia, Canada
• Worldwide but suppressed
• Virus closely related to BoCoV and IBV

Pathogenesis

1. Infection PO
2. Replication in epithelial cells of small intestine and caecum and in bursa Fabricii
3. Morbidity: 100%, Age-dependent mortality: 0-50%

Question 11

Clinical signs and protection of Coronaviral enteritis of turkey?

Answer 11

Clinical signs

• Incubation: 1-5 days, lasts 2 weeks
• Rapid spread
• Loss of appetite, depression
• Diarrhoea (foamy, watery), exsiccosis, anorexia, blue comb, decreased egg production
• Spiking mortality syndrome in severe cases
• No maternal immunity

Protection

• No vaccines
• Eradication
• Seroconversion (where endemic)