Clinical signs in affected birds are often
indicators of the disease and should be recorded in
the epidemiological enquiry form (Annexure
Low pathogenic strains
Mild to severe respiratory symptoms.
Decrease in egg production up to 45% (takes 2 -
4 weeks to recover)
Mortality 3% (layers), 15% (broilers).
Severe respiratory distress, depression, ruffled
Watery eyes and sinuses.
Cyanosis of combs, wattles and shanks.
Edema of head and sinuses.
Diarrhea (initially bright green later white).
Nervous signs as with highly virulent Newcastle (Ranikhet)
Sudden death (within 24 hrs of first signs),
mortality can approach 100%.
HPAI virus needs to be differentiated from Newcastle disease,
Infectious laryngo-tracheitis (ILT), fowl cholera
(caused by Pasteurella
other diseases which induce similar clinical signs
Post mortem lésions:
In per-acute cases (day 1 & 2), death occurs without
gross lesions. Generally, congestion, hemorrhage and
edema are found in internal organs. In acute cases
(day 3 –5), the following lesions are observed:
Subcutaneous edema of head and neck.
Conjunctivae congested and petechiated.
Abdominal fat, serosa, peritoneum with pinpoint
Diffuse haemorrhages between hock and feet and
Petechiation of whole viscera.
Air sacculitis, peritonitis (cattarhal,
Atrophy of lymphoid organs.
Perivascular cuffing (PVC) of lymphocytes in
brain, heart, spleen, pancreas.
Coagulative necrosis in kidney, lungs, spleen.
Edema, hyperaemia, hemorrhage in heart muscles.
Necrotic epithelial and urate casts in kidney
Links to other information
resources of Avian Influenza
For Laboratory Diagnosis of AI, please refer to Lab
Diagnosis of AI
For guidelines to send samples of AI to NIHSAD,
please refer to Annexure
detailed information about control of AI in
India, please download the Action
Plan, 2006 prepared by DADF,
Ministry of Agriculture, Govt. of India.
Collection and shipment of
Avian Influenza samples to NIHSAD
For general guidelines about collection and
shipment of diagnostic specimens, please refer
2008 manual- chap. 1.1.1