Occurrence: Worldwide.
Species affected: Chickens only.
Age affected: All, young are most susceptible.
Causes: Infectious bronchitis virus is a coronavirus, and is the most contagious viral respiratory disease in poultry.
Effects: Sneezing and watery eyes are seen early on, followed by depression, coughing and nasal discharge. Producing birds exhibit drop in egg production or weight gain. Eggs have poor shell quality and watery albumin. Layers also have ruffled feathers and wet droppings. Tracheal rales, gasping and urate diarrhoea are also seen.