Infectious Bronchitis (IB) disease is one of the highly contagious viral diseases caused by the Infectious Bronchitis Virus (IBV), a member of the Coronaviridae family. The disease primarily targets the respiratory system of chickens but infectious bronchitis can also affect the reproductive system and ultimately affect egg production, and renal systems, leading to significant economic losses in poultry farming. The effect of infectious bronchitis is a dramatic decline in egg production. Infected hens may produce fewer eggs, and those laid are often misshapen, have thin or rough shells, or contain watery albumen. The virus disrupts the normal functioning of the oviduct, which is responsible for egg formation. If the infection occurs during a critical developmental stage, it can cause permanent damage to the oviduct, rendering the bird incapable of laying eggs altogether.
Pathogenesis and Mechanism Behind Egg-Laying Disruption
The pathogenesis of IB begins when the virus enters the chicken’s body via inhalation or ingestion, targeting epithelial cells in the respiratory tract. Within 18–36 hours post-infection, the virus rapidly replicates, causing inflammation and congestion in the trachea and air sacs, leading to symptoms like coughing, sneezing, and nasal discharge. As the infection spreads to the reproductive system, the virus causes necrosis and inflammation in the oviduct tissues. This damage disrupts the hormonal signals and mechanical processes required for normal egg development. In cases of severe infection, the oviduct may atrophy, permanently impairing egg production. Studies indicate that IB outbreaks can reduce egg production by up to 50%, with some flocks requiring weeks to recover fully.
Economic and Preventive Measures
The economic implications of IB extend beyond reduced egg production. Poor-quality eggs are often unsellable, and secondary bacterial infections, such as Escherichia coli, can further exacerbate flock health issues, increasing treatment costs. Vaccination programs tailored to specific IBV strains are a critical component of disease management, helping to reduce the severity and spread of the disease. However, due to the high mutation rate of IBV, new strains frequently emerge, posing a challenge for vaccine efficacy. Biosecurity measures, including regular cleaning, disinfection, and controlling the movement of people and equipment, play a vital role in preventing outbreaks. Understanding the epidemiology of IB and implementing integrated disease control strategies are essential to mitigate its impact on poultry health and productivity.
