Infectious bronchitis in poultry

Related to veterinary pathology

1. Infectious Bronchitis Suggested By - Submitted By – Dr A.K. Srivastava Pratiksha Srivastava Dr Neeraj Gangwar 3 rd Yr, 6 th Semester B.V.Sc & A.H Department Of Veterinary Pathology, DUVASU

2. Introduction First reported in 1931 in U.S.A. Highly infectious & contagious respiratory disease. Great economic importance due to adverse effect on production. Caused By – IB Virus ( Corona Virus ) Corona Virus – Enveloped , pleomorphic , Positive Sense ssRNA virus, pear shaped peplomers present on envelope which lacks matrix protein. Capsid on virus show crown like pattern. Helical Symmetry present.

3. Replication of Coronavirus

4. Serotypes Of Virus Massachusetts Affinity for respiratory Tract Connecticut T Gray Nephrotoxic Nature Holte Hosts Chicken – Naturally infected. Respiratory form – more severe in chicks. Nephritic Form – seen in birds under 10 wk of age.

5. Spread Direct airborne transmission – most common. Via Infected Faeces . Through fomites . Transmission via egg – exceptional. Forms Of Disease Respiratory Nephritic Genital GIT ( Enteropathogenic Form )

6. Pathogenesis Virus readily infects respiratory tract ,intestinal tract, kidneys and oviducts. New virus start to appear 3 to 4 h after infection. Maximum output reaches in 12 h. In many cases recovery occurs unless chickens are very young or air sacculitis develops from secondary bacterial infections.

7. Air Sacculitis

8. Signs Respiratory Signs – Rales , gasping, sneezing, watery nasal discharge, lachrymation & swelling. Chicks huddle under source of light.

9. Genital Form – Cystic dilatation in oviduct, thin shelled misshaped eggs, Watery albumin, Internal ovulation may occur.

10. Watery Albumin

11. Nephritic Form – Marked depression

12. Enteropathogenic Form - Diarrhoea

13. Lesions Gross – Caseous plug in bronchi at point of entry in lungs. Air sacs may appear cloudy, may contain yellow caseous exudate . Bronchial mucosa very much thickened. Ureters filled with white chalky substance ( urates ). Juction of isthmus & magnum get atrophied.

14. White Caseous Plug in Bronchi Accumulation Of White Urates

15. Microscopic – Tracheal mucosa – oedematous , loss of cilia, rounding & sloughing of epithelial cells. Interstitial nephritis in kidney, granular degeneration, vacuolation & desquamation of tubular epithelium ( prominent in medula ), focal areas of necrosis, ureters distended with urates . In oviduct – decrease in height & loss of cilia from epithelial cells, dilation of tubular glands.

16. Oedema in Trachea Ureter distended with Urates

17. Diagnosis On the basis of symptoms & lesions. Isolation & Identification of virus. Samples to be collected – trachea, bronchi, caecal tonsils. 9 – 11 days old Embryonated chicken egg inoculation via allantoic sac route – after 3-4 days curling & dwarfing of embryo is seen. Tracheal Organ Culture (TOC) Immunoperoxidase Assays Ab detection by – VNT, ID, Immunoflourescence , ELISA.

18. Thickened amnion & Allantois Stunting & Curling Of embyoes

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