Coccidiosis is a parasitic disease of the digestive tract.
It is difficult to control by sanitation practices alone. The best prevention is to include a drug or coccidiostat in the feed. This coccidiostat is added to the feed at low levels and fed continuously. Some coccidiostats can be given at higher levels to treat the disease after the birds show symptoms. Before increasing the drug level, check with someone who is familiar with the proper use of the coccidiostat in question since some coccidiostats can be toxic at higher levels.