This is an acute and highly contagious respiratory disease of the chicken. It is characterized by respiratory signs like gasping, coughing, sneezing, tracheal rales and discharge from nasal area. In layers, the distress decreases the egg production and loses internal egg quality and egg shell quality.
Infectious bronchitis is only found in chickens, and it is world wide. Normally experienced during cooler months. It is said to have been first found in 1931 in USA. It was found in young chickens but since then it has been identified in broilers and layers as well.
The virus is spread through droplets expelled during coughing and sneezing by the infected chicken. It thus makes it easy to spread in a flock very fast. Transmission can also be enhanced by movement of people, equipment and vehicles from farm to farm. The signs are coughing, sneezing and rales may be observed. Also a drop of egg production from 5 to 10%. Eggs produced during this disease have thin shells and loss of pigment in brown shelled eggs. To prevent vaccination is important.
Prevention of infectious bronchitis (IB) is best achieved through an effective bio security program. As a second line of defense, chickens in IB problem areas should be vaccinated with modified live vaccines to provide protection. The multiplicity of stereotypes identified in the field presents a challenge in designing an effective vaccination program.
To be successful in protecting chickens against challenge, it is essential to identify the prevalent serotypes in the region and to determine the cross-protective potential of available vaccines. In North America, the common serotypes used in most vaccination programs are the Massachusetts, Connecticut, and Arkansas serotypes. These serotypes are available in both modified live vaccines and inactivated water-in-oil emulsions.