Coccidia are tiny single-celled parasites that live in the wall of your cat’s (or dog's) intestine. They are found more often in kittens, but they can also infect older cats.
Cats become infected by swallowing soil that contains coccidia or other substances in the environment that may contain cat feces It is also possible that rodents could eat the coccidia and contract a “resting” stage of the parasite. Cats that are old enough to hunt could then be infected when they hunt and eat these animals. Cats are more likely to get infected with coccidia by this method than dogs are.
Coccidiosis, the disease caused by coccidia, is usually more serious in kittens but can occur in older cats. The most common sign of coccidiosis is diarrhea. Severe infections, especially in kittens, can kill them.
Coccidial infections can be prevented by cleaning your cat’s litter box regularly and by preventing your cat from hunting. Because coccidia are found most often in kittens, it is important to have kittens examined for the parasite as soon as possible. Your veterinarian can perform a fecal test to diagnose coccidiosis. If your cat is infected with coccidia, your veterinarian is able to give it effective medications.
A cat that is infected with coccidia cannot pass the infection to dogs and vice versa. Coccidial infections in cats occur only by swallowing the coccidia in soil or cat feces or by eating intermediate hosts.