Causative agent 
- IB virus, family Coronaviridae
- Great antigentic variation and many serotypes



Differential diagnosis 
- Newcastle disease
- Infectious laryngotracheitis
- Infectious coryza
- Egg drop syndrome
- Mycoplasmosis
- Nephritis



1. History taking 
- Affect all ages of chickens
- Rapid transmission from flock to flock but low
  mortality
- Outbreak can occur even in vaccinated flock



2. Clinical examination 
- Respiratory signs with tracheal rales
- Drop in egg production and quality
- In some outbreaks, diarrhea is conspicuous but
  the respiratory signs are mild (nephro-nephritis
  type)



3. Necropsy 
- Mild to moderate inflammation of the respiratory
  tract
- Softening and rupture of ovarian follicles
- Swelling of kidney, dilation of ureter with urate

4. Histopathological observation 
- Hyperplasia of respiratory epithelium, cellular
  infiltration of respiratory mucosa and submucosa
  mainly of lymphoid cells, and slight pulmonary
  edema
- Nephro-nephritis
- Lymphocytes and plasma cells infiltration in whole
  area of oviduct



5. Antigen detection 
Specimen : frozen section of trachea, bronchi,
                  lung, kidney
Method    : FA test



6. Virus isolation 
Specimen : tracheal mucosa, bronchi, lung, air
                  sac, kidney
Method    : chick embryo inoculation at 9-11
                  days of age by CAC route, 3-5 blind
                  serial passages and observe stunt,
                  curling of the embryos with urate
                  deposits in the mesonephros



7. Virus Identification 
- VN test
- FA test

Control 
- Vaccination with live attenuated and inactivated
  vaccine