Giardiasis is a diarrheal illness caused by a microscopic parasite, Giardia. Once a person or animal is infected, the parasite lives in the intestine and is passed in the stool. Because it has an outer shell, it can survive outside for long periods of time. Giardia is found in soil, food, water or sufaces that have been contaminated with the feces from infected animals or humans. Giardia infection is very contagious. Giardia infections in dogs and cats may produce weight loss and chronic diarrhea.
Sarcoptic mange is also very contagious and easily transmittable. It is caused by a mite that burrows into the top of an animal’s skin. Secondary bacterial infections or fungal infections are common and make mange harder to treat.
Source: Centers for Disease Control