Infectious Bronchitis (IB) is a highly contagious and acute disease and is caused by an avian coronavirus which targets not only the respiratory tract but also the uro-genital tract. Several different IB serotypes have been identified in the field, such as classic Massachusetts and a number of variants such as 793B, QX, D274 and Arkansas. The virus is spread horizontally via the airborne route. The incubation period is only 1-3 days.
Although IB mainly affects chickens, other poultry species such as quail and pheasants can also be affected.
Drop in egg production
Increased number of poor quality eggs
Respiratory signs such as coughing and gasping
Loss of appetite
Increased water intake
Diagnosis based only on clinical signs is very difficult, as many respiratory signs are similar to other diseases such as ILT and ND. Definitive diagnosis must be confirmed by laboratory confirmation based on virus isolation and identification with PCR and serology.
Currently there is no treatment for IB and antibiotics are used to control secondary bacterial infections.
The virus is easily destroyed by heat and ordinary disinfectants. In young chickens it is helpful to increase the brooder temperature and to optimise environmental conditions.
There are many strain specific live vaccines, and for layers and breeders the addition of inactivated vaccines at point of lay to induce long lasting systematic immunity.
To ensure optimum protection it is important to try and use homologous live vaccines. Where a homologous strain vaccine is not available vaccines containing more than one strain can be used to provide as broad a protection as possible. This is often referred to as cross protection.