Flukes are obligate parasitic flatworms that infect the blood vessels, gastrointestinal tract, lungs, or liver. They typically have complex life cycles requiring the involvement of at least 2 hosts. They are often categorized according to the principal organ system they invade:
Clonorchis sinensis, Fasciola hepatica, and Opisthorchis species: Liver and bile ducts
Fasciolopsis buski, Heterophyes heterophyes, and related organisms: Lumen of the gastrointestinal tract
Paragonimus westermani and related species: Lungs
Schistosoma species: Vasculature of the gastrointestinal or genitourinary system
