CSU ext

Giardiasis -  A gastrointestinal disease of animals and humans caused by the microscopic parasite Giardia intestinalis. Commonly referred to as“giardia”, it is a zoonotic disease and affects humans and all animals.

Giardis drawing
Drawing of a giardia
How is it transmitted? Contamination of water and food sources with fecal material from an animal or person infected by the parasite. Water in swimming pools, hot tubs, lakes, rivers, springs, ponds, or streams can be contaminated with sewage or feces from humans or animals.

Natural stream
Streams may be contaminated with Giardia

What are the signs in animals? Diarrhea, bloat, dehydration and weight loss.

What are the symptoms in humans?  Giardia infection can cause a variety of intestinal symptoms including; diarrhea, gas or flatulence, greasy stools that tend to float, stomach cramps, upset stomach and nausea.  These symptoms may lead to weight loss and dehydration. Symptoms normally begin 1 to 2 weeks  after becoming infected, while some people will have no symptoms.
More information at Merck Vet Manual: