Related to veterinary pathology

1. Suggested By Dr A.K. Srivastava
Dr Neeraj Gangwar
Submitted By –
Pratiksha Srivastava
3rd Yr, 6th 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
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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
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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

19. Thank You