Giardia are single-celled organisms, infectious to many types of animals (including humans) all over the world. Their presence in the host intestine can cause diarrhea, though some hosts are symptom-free carriers.

Itchy skin in the small animal is often more than just a minor annoyance. Red, oozing bald patches; rashes; and large expanses of hair loss are unfortunate markers of very real discomfort for which a cause should be sought and dealt with.