Diagnosis of Infectious Bronchitis on the basis of clinical signs alone is very difficult.
- Respiratory signs ‐ Respiratory signs similar to IB are observed in many other respiratory diseases such as Newcastle Disease, Infectious Laryngotracheitis or Pneumovirus infections. Often these diseases may present themselves in milder forms making it impossible to distinguish one from the other.
- Decreased egg production and poor egg quality ‐ The sign “egg drop” is even less specific. Post mortem findings are often not conclusive.
Laboratory tests to identify the viral genome, viral antigen (proteins) or antibodies against the virus are important to confirm IBV infections.
Testing serum samples at intervals (for example at the time of the clinical signs and 2 or 3 weeks later) provide the best basis for serological diagnosis. This is also applicable for monitoring vaccination results.