-
This is an illustration of the life cycle of Paragonimus westermani, one of the causal agents of Paragonimiasis.Created: 2002
-
Magnified 128X, this photomicrograph revealed some of the ultrastructural morphology of a single trematode Paragonimus westermani egg. P. westermani eggs range from 80µm to 120µm long X 45µm to 70µm 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. See PHIL 1534 for an even closer view of this egg.Created: 1979
-
Magnified 500X, this photomicrograph of an unstained, formalin-preserved stool specimen mount, revealed the presence of a Paragonimus westermani termatode egg. See PHIL 3415 for the depiction of the following life cycle.The eggs are excreted unembryonated in the sputum, or alternately they are swallowed and passed with stool (1). In the external environment, the eggs become embryonated (2), and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues (3). Miracidia go through several developmental stages inside the snail (4): sporocysts (4a), rediae (4b), with the latter giving rise to many cercariae (4c), which emerge from the snail. The cercariae invade the second intermediate host, a crustacean such as a crab or crayfish, where they encyst and become metacercariae. This is the infective stage for the mammalian host (5).Created: 1973
-
Magnified 500X, this photomicrograph of an unstained, formalin-preserved stool specimen mount, revealed the presence of a Paragonimus westermani termatode egg. See PHIL 3415 for the depiction of the following life cycle.The eggs are excreted unembryonated in the sputum, or alternately they are swallowed and passed with stool (1). In the external environment, the eggs become embryonated (2), and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues (3). Miracidia go through several developmental stages inside the snail (4): sporocysts (4a), rediae (4b), with the latter giving rise to many cercariae (4c), which emerge from the snail. The cercariae invade the second intermediate host, a crustacean such as a crab or crayfish, where they encyst and become metacercariae. This is the infective stage for the mammalian host (5).Created: 1973
