Aspergillosis is a serious fungal disease affecting turkeys, especially young birds, caused by breathing in fungal spores from moldy hay, compost or poorly ventilated housing. The disease causes respiratory problems, can spread to other organs, and can kill 30-50% of affected flocks. Prevention through good ventilation, clean housing and dry feed is more effective than treatment since few antifungal drugs are approved for food animals. Understanding how environmental conditions promote this disease is key to protecting turkey populations.