Fasciolopsis: A parasite that is the largest intestinal fluke in humans. Known scientifically as Fasciolopsis buski and popularly as the giant intestinal fluke. Infection occurs primarily in Asia and the Indian subcontinent, especially in areas where humans raise pigs and consume freshwater plants. The immature eggs of the fluke in human feces reach fresh water where they hatch and form what are called miracidia. Upon contact with host snails, the miracidia penetrate them and form cercariae. The cercariae encyst on various plants such as the water chestnut, lotus (on the roots), water bamboo, and other aquatic vegetables. Humans are infected by consuming these raw vegetables. Most infections are light and asymptomatic. Heavy infection may cause nausea, diarrhea, malabsorption, or intestinal obstruction. Diagnosis is made by microscopic identification of the fluke eggs or, more rarely, the adult flukes in the stool or vomitus. Praziquantel is the drug of choice for treatment.