Giardiasis, also known as the giardia infection, is an infection of the intestines. It is caused very small parasite called giardia. The giardia parasite can be found all over the world and is a waterborne infection. The parasite that causes giardiasis is most commonly found in places where unsanitary water and poor sanitation. It may be found in places like lakes, swimming pools, and wells. The most common signs and symptoms include abdominal cramps, bloating, nausea and watery diarrhea. The giardia infection usually goes away within a couple of weeks. It is estimated that about two percent of people in the United States are infected with giardia.