Symptoms of giardiasis include diarrhea, flatulence or gas, upset stomach, dehydration and stomach cramps, according to the Centers for Disease Control. Additionally, the Mayo Clinic lists fatigue, belching with a bad taste and foul smelling stools that alternate between diarrhea and soft, greasy stools as symptoms.
Giardiasis is caused by a parasite known as giardia, according to the CDC. Once inside the host's body, it moves to the digestive tract, specifically the intestines. The parasite is passed through the feces of an infected person or animal, and anything that potentially comes into contact with the feces may transmit the parasite. Typically, symptoms appear between one and three weeks after contracting the parasite. Some people don't develop symptoms at all but are still able to pass it to others. In healthy people, the CDC expects symptoms to last anywhere from two to six weeks. Several prescription medicines may be able to shorten the symptomatic period. The CDC suggests visiting a health care provider if any of the above symptoms are present. People who have children in child care, who go backpacking or who may have swallowed water while playing in an area such as a lake or river are at a greater risk to contract the parasite and are encouraged to see a doctor as soon as symptoms appear.