Broiler chickens will show poor weight gain and may develop secondary bacterial infections. Infected birds usually cough, because of excessive mucus in their trachea. This disease spreads rapidly through the entire flock. In uncomplicated cases, the flock recovers quickly. There is no effective treatment.
Prevention is by vaccination.
In any case of respiratory illness, it is important to know if you're dealing with a viral, bacterial, fungal or parasitic disease. The treatment for one disease may be ineffective or even harmful for others. Microscopic evaluation of affected tissues is helpful and can be performed at a diagnostic laboratory. A fecal test for parasites also should be done. Attempts to isolate virus may be required.