Cats can shed gastrointestinal parasites in their feces, including roundworms, tapeworms, hookworms, whipworms, heartworms, and single-celled organisms including Giardia and Toxoplasma gondii.

Cats in hats ... got rid of the Giardia in her system, but what is it? PetMD describes Giardiasis as a single-celled "protozoan" orally ingested through contaminated water, stool, or soil and ...