The metacercarial stage is infective to humans and other fish-eating mammals, including dogs, cats, rats, and pigs. Fish contain more metacercaria from September to February, before the dry season, and this is when humans are usually infected. Infection is acquired when people ingest raw or undercooked fish. Dishes of raw fish are common in the cuisine of Laos and the cuisine of Thailand: "koi pla", raw fish in spicy salad "larb pla", salted semifermented fish dishes called "pla ra", "pla som" and "som fak". The natural definitive host is the leopard cat ("Prionailurus bengalensis"). The young adult worm escapes from the metacercarial cyst in the upper small intestine and then migrates through the ampulla of Vater into the biliary tree, where it develops to sexual maturity over 4–6 weeks, thus completing the lifecycle.