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eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

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eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

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eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

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eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

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eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

View in Context

eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

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eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

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eFigure 37–20. Life cycle of Schistosoma. Eggs are eliminated with feces or urine . Under optimal conditions the eggs hatch and release miracidia , which swim and penetrate specific snail intermediate hosts . The stages in the snail include two generations of sporocysts and the production of cercariae . Upon release from the snail, the infective cercariae swim, penetrate the skin of the human host , and shed their forked tail, becoming schistosomulae . The schistosomulae migrate through several tissues and stages to their residence in the veins , ). Adult worms in humans reside in the mesenteric venules in various locations, which at times seem to be specific for each species . For instance, Schistosoma japonicum is more frequently found in the superior mesenteric veins draining the small intestine , and Schistosoma mansoni occurs more often in the superior mesenteric veins draining the large intestine . However, both species can occupy either location, and they are capable of moving between sites, so it is not possible to state unequivocally that one species only occurs in one location. Schistosoma haematobium most often occurs in the venous plexus of bladder , but it can also be found in the rectal venules. The females (size 7–20 mm; males slightly smaller) deposit eggs in the small venules of the portal and perivesical systems. The eggs are moved progressively toward the lumen of the intestine (S mansoni and S japonicum) and of the bladder and ureters (S haematobium), and are eliminated with feces or urine, respectively . Pathology of S mansoni and S japonicum schistosomiasis includes Katayama fever, hepatic perisinusoidal egg granulomas, Symmers pipe stem periportal fibrosis, portal hypertension, and occasional embolic egg granulomas in brain or spinal cord. Pathology of S haematobium schistosomiasis includes hematuria, scarring, calcification, squamous cell carcinoma, and occasional embolic egg granulomas in brain or spinal cord. Human contact with water is thus necessary for infection by schistosomes. Various animals, such as dogs, cats, rodents, pigs, horse and goats, serve as reservoirs for S japonicum, and dogs for Schistosoma mekongi. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Schistomia species.

Current Medical Diagnosis & Treatment 2024 > Schistosomiasis (Bilharziasis)

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–23. Life cycles of Fasciola hepatica and Fasciola gigantica (liver flukes). Immature eggs are discharged in the biliary ducts and in the stool . Eggs become embryonated in water , eggs release miracidia , which invade a suitable snail intermediate host , including the genera Galba, Fossaria, and Pseudosuccinea. In the snail, the parasites undergo several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and encyst as metacercariae on aquatic vegetation or other surfaces. Mammals acquire the infection by eating vegetation containing metacercariae. Humans can become infected by ingesting metacercariae-containing freshwater plants, especially watercress . After ingestion, the metacercariae excyst in the duodenum and migrate through the intestinal wall, the peritoneal cavity, and the liver parenchyma into the biliary ducts, where they develop into adults . In humans, maturation from metacercariae into adult flukes takes approximately 3–4 months. The adult flukes (F hepatica: up to 30 mm by 13 mm; F gigantica: up to 75 mm) reside in the large biliary ducts of the mammalian host. F hepatica infects various animal species, mostly herbivores. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Fasciola species.

Current Medical Diagnosis & Treatment 2024 > Fascioliasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–24. Life cycle of Clonorchis sinensis (Chinese liver fluke). Embryonated eggs are discharged in the biliary ducts and in the stool. Eggs are ingested by a suitable snail intermediate host . Each egg releases a miracidia , which go through several developmental stages (sporocysts , rediae , and cercariae ). The cercariae are released from the snail and after a short period of free-swimming time in water, they come in contact and penetrate the flesh of freshwater fish, where they encyst as metacercariae . Infection of humans occurs by ingestion of undercooked, salted, pickled, or smoked freshwater fish . After ingestion, the metacercariae excyst in the duodenum and ascend the biliary tract through the ampulla of Vater . Maturation takes approximately 1 month. The adult flukes (measuring 10–25 mm by 3–5 mm) reside in small- and medium-sized biliary ducts. In addition to humans, carnivorous animals can serve as reservoir hosts. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of Trematode species.

Current Medical Diagnosis & Treatment 2024 > Clonorchiasis & Opisthorchiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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eFigure 37–26. Life cycle of Paragonimus westermani (lung fluke). The eggs are excreted unembryonated in the sputum, or alternately, they are swallowed and passed with stool . In the external environment, the eggs become embryonated , and miracidia hatch and seek the first intermediate host, a snail, and penetrate its soft tissues . Miracidia go through several developmental stages inside the snail : sporocysts , rediae , with the latter giving rise to many cercariae , 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 . Human infection with P westermani occurs by eating inadequately cooked or pickled crab or crayfish that harbor metacercariae of the parasite . The metacercariae excyst in the duodenum , penetrate through the intestinal wall into the peritoneal cavity, then through the abdominal wall and diaphragm into the lungs, where they become encapsulated and develop into adults (7.5–12 mm by 4–6 mm). The worms can also reach other organs and tissues, such as the brain and striated muscles, respectively. However, when this takes place completion of the life cycle is not achieved because the eggs laid cannot exit these sites. Time from infection to oviposition is 65–90 days. Infections may persist for 20 years in humans. Animals such as pigs, dogs, and a variety of feline species can also harbor P westermani. (From Global Health, Division of Parasitic Diseases and Malaria, CDC.) A flowchart of the life cycle of P westermani.

Current Medical Diagnosis & Treatment 2024 > Paragonimiasis

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