Paragonimiasis | Lung fluke and its Life Cycle

Paragonimus westermani (Japanese lung fluke or oriental lung fluke) is the most common species of lung fluke that infects humans, causing paragonimiasis Human infections are most common in eastern Asia and in South America.
More than 30 species of trematodes (flukes) of the genus Paragonimus have been reported to infect animals and humans. Among the more than 10 species reported to infect humans, the most common is Paragonimus westermani, the oriental lung fluke.
Eggs: Paragonimus westermani eggs range from 80 to 120 μm long by 45 to 70 μm wide. They are yellow-brown, ovoid or elongate, with a thick shell, and often asymmetrical with one end slightly flattened. At the large end, the operculum is clearly visible. The opposite (abopercular) end is thickened. The eggs are unembryonated when passed in sputum or feces.[4]
Cercaria (not shown): Cercariae are often indistinguishable between species. There is a large posterior sucker, and the exterior is spined.
Metacercaria: Metacercariae are usually encysted in tissue. The exterior is spined and has two suckers
Adults: Adult flukes are typically reddish-brown and ovoid, measuring 7 to 16 mm by 4 to 8 mm, similar in size and appearance to a coffee bean. They are hermaphroditic, with a lobed ovary located anterior to two branching testes. Like all members of the Trematoda, they possess oral and ventral suckers.