Causative agent 
- ILT virus, family Herpesviridae



Differential diagnosis 
- Acute infectious bronchitis
- Newcastle disease
- Infectious coryza
- Fowl pox
- Mycoplasmosis
- Avian influenza
- Avitaminosis A



1. History taking 
- Chicken of all ages are susceptible
- Incidence relate to recent introduction of new
  chickens to farm, recent visit of man associated
  with poultry farms or similar disease in farms
  nearby



2. Clinical examination 
- Acute form : nasal discharge and moist rales
  followed by gasping and coughing out bloody
  tracheal obstruction (characteristic signs)
- Mild form : conjunctivitis with watery eyes,
  lacrimation and nasal discharge, swollen
  infraorbital sinuses, lower egg production



3. Necropsy 
- Severe laryngotracheitis, tracheal hemorrhage
  with bloody exudate
- Diptheritic membrane or cheesy plug in the
  upper trachea and larynx
- Edema and congestion of conjunctiva and
  infraorbital sinuses

4. Histopathological observation 
- lntranuclear inclusion bodies in the respiratory
  mucus membrane of larynx, trachea and lung
- Desquamation of tracheal epithelium and
  lymphocytes, plasma cells and histocytes
  infiltration into mucosa and submucosa
- Hemorrhage of tracheal mucosa and separation
  of mucosa and submucosa



5. Antigen detection 
Specimen : tracheal smear
Method    : FA test and observe fluorescence in the
                  cytoplasm and nuclei of infected cells



6. Virus isolation 
Specimen : trachea, lung
Method :
1. chick embryo inoculation at 9-11 days of age by
    CAM route and observation of circular, irregularly
    outlined, thickening plaque lesions on the CAM
2. CK inoculation and CPE observation of
    multinucleated polykaryocytes (syncytial cells)



7. Virus identification 
- VN test
- FA test

Control 
- Vaccination
- Site quarantine and hygiene measurement
- Avoidance of adding vaccinated or recovered
  birds to a susceptible flock