Coccidiosis is a disease which affects many species of animal, and can have serious animal welfare and economic consequences, particularly in groups of animals such as poultry & game birds.  Coccidia are microscopic single-celled parasites (called protozoa) that live within cells and are usually found in the intestinal tract.  The disease is caused by the internal parasite and is always more common in young birds, it usually strikes chickens up to 12 weeks of age.
Signs of Coccidiosis
Birds infected with coccidiosis look dull and lifeless; they will stand hunched up with ruffled feathers with their wings dropped and eyes closed. They will not be eating much and will consequently lose weight. The faeces may be blood stained or contain red coloured jelly like worms.
Effects of Coccidiosis
Unfortunately one of the main effects of the disease is mortality; the rates will vary but can be in excess of 50%, depending on the housing conditions, the existence of an anti-coccidial supplement in the feed and the natural immunity levels of the bird.  If the birds are receiving no treatment in their feed, the onset will be rapid and the losses are likely to be high. Survivors of an outbreak will show few outward signs but their gut will be scarred and they consequently may not be as efficient at converting their food.
There is a range of drugs available for the successful treatment of the disease. These require a prescription and should be used as per veterinary advice to achieve the best results.
The use of medicated feed is generally considered as one of the best preventative measures against coccidiosis. This can be fed throughout the rearing period and replaced with a standard pellet just before the point of lay or slaughter, paying careful attention to the withdrawal period associated with medicated feed. Good husbandry is also an important part of prevention; correct stocking rates, dry bedding, good ventilation and cleanliness of feeders and drinkers will all help to hinder development of the parasites.