DIAGNOSIS: Characteristic coughing and gasping. Virus can be isolated in embryonated eggs from tracheal swabs. Rising antibody titres may be demonstrated in infected birds.

CONTROL OF DISEASE: Combination of maternal passive and active immunity. Chicks are vaccinated within the first week with an attenuated vaccine by aerosol or in drinking water. Cross-serotype protection occurs but virus strains relevant to local area are used.