Diseases: Infectious Bronchitis

Introduction

• A group of respiratory, reproductive and nephritic (kidney) diseases of chickens caused by strains of coronavirus
• Affects chickens of all ages, but disease is most severe in baby chicks.

Clinical Signs

• Respiratory form:
  Very short incubation period
  Coughing, sneezing, gasping
  Nasal discharge in young chicks
  Mortality may be high in young chicks
• Reproductive form:
  Reduced egg production
  Eggs may be misshapen and shells may be thin and soft
• Nephritic form:
  Wet droppings
  Increased intake of water
  Rapid weight loss
  Mortality in young chicks up to 25%

Post Mortem Lesions

• Some strains: pale enlarged kidneys containing white deposits (urates)
• Trachea, sinuses and air sacs reddened and may contain fluid

Diagnosis

• Confirm by isolation of virus or demonstration of presence of virus
• Clinical signs are not diagnostic

Sample Collection

• Tracheal swabs
• Caecal tonsils
• Cloacal swabs
• Lungs, kidneys and oviduct, if suggested by clinical signs and post mortem lesions

Transmission

• Highly contagious between infected and susceptible birds
• Airborne spread
• By contamination of personnel and equipment
• Virus is fragile – survives in the environment at 15 to 20oC for only a few days
• Virus may survive in litter containing faces for a considerable time.

Treatment

• No specific treatment
• Good nursing - keep the birds warm, and allow easy access to food and water to help to reduce losses.

Prevention and Control

• Vaccines are available but must use strain that matches strains of virus circulating in flock
• Isolation of sick chickens
• Do not introduce sick or new chickens into flock.