Giardia infection (giardiasis) is an intestinal infection caused by a microscopic parasite that's found worldwide, especially in areas with poor sanitation and unsafe water. Giardia infection is marked by abdominal cramps, bloating, nausea and bouts of watery diarrhea.
Giardia infection is a waterborne infection and can be caused by parasites found in backcountry streams and lakes, as well as in municipal water supplies, swimming pools, whirlpool spas and wells. Giardia infection can also be transmitted through food and person-to-person contact.
Giardia infections usually clear up within a few weeks. But you may have intestinal problems long after the parasites are gone. Several drugs are generally effective against giardia parasites, but not everyone responds to them. Prevention is your best defense.