virus (6) volaille (4) Control (4) Origin (4) Vaccines (4) Poultry (4) Chickens (4) Origin (4) information (3) infection (3) analyse (3) embryon (3) Causes (3) Reading (3) Infection (3) Evidence (3) Reading (3) Analysis (3) Transmission (3) maladie respiratoire (2) champ (2) maladie (2) comparaison (2) Comparison (2) White (2) Viruses (2) Symptoms (2) Immune response (2) Days (2) Canada, Western (2)