Digenea Trematoda Flukes Chapter 4 Learning Objectives 1
Digenea Trematoda - Flukes Chapter 4
Learning Objectives 1. Define terminology specific for Digenea. 2. State scientific and common names of flukes that parasitize humans. 3. Describe the general morphology of adult hermaphroditic trematodes. 4. Describe the general morphology of adult schistosomes. 5. Describe in graphic form the life cycle of adult trematodes. 4 -2
Learning Objectives 6. State the methods of diagnosis used to identify fluke infections. 7. Differentiate adult trematodes using morphologic criteria. 8. Differentiate diagnostic stages of trematodes. 9. Classify the methods by which the flukes infect humans. 10. Compare and contrast the morphology of adult Cestoda and Digenea. 4 -3
Learning Objectives 11. Given an illustration or photograph, identify diagnostic stages of trematodes and the body specimen of choice to be used for examination of each. 12. Discriminate among the trematodes on the basis of the required intermediate host(s). 4 -4
Introduction Classification General body structure Hermaphroditic flukes Schistosoma spp. Life cycle Hermaphroditic flukes Schistosoma spp. 4 -5
Trematode Life Cycle 4 -6
Trematodes ( flukes) • Fasciolopsis buski – Large intestinal fluke • Fasciola hepatica – Sheep liver fluke • Clonorchis sinensis – Chinese liver fluke • Paragonimus westermani – Oriental lung fluke • Schistosoma mansoni – Manson’s blood fluke • Schistosoma japonicum – Oriental blood fluke • Schistosoma haematobium – Bladder fluke • Heterophyes heterophyes – heterophyids ( intestine) • Metagonimus yokogawii – heterophyids (intestine) 4 -7
Fasciolopsis buski (large intestinal fluke) and Fasciola hepatica (sheep liver fluke) Method of diagnosis Diagnostic stage Disease names Major pathology and symptoms Treatment Distribution 4 -8
F. Hepatica & F. buski – Life cycle 4 -9
F. hepatica & F. buski life cycle • F. hepatica – adults in liver (bile duct); F. buski – adults in small intestine • Fertilized eggs in feces ( DS ) • Eggs hatch in fresh water – larva invade snail ( intermediate host #1) • Larva develop into cercaria – leave snail • Meta cercaria encyst on water plants • Human eats metacercaria on water plants ( IS ) 4 -10
Fasciola hepatica (Sheep Liver fluke) adult • Worldwide in sheep raising areas • Not common in U. S. • Sheep – natural host • Humans –accidental host • Snail – intermediate host • DS – eggs in feces • IS – metacercaria form cysts on aquatic vegetation • Eggs can’t be differentiated from F. buski eggs 4 -11
F. Hepatica egg – Note size & operculum 4 -12
F. hepatica egg • Eggs cannot be differentiated from F. buski • Both eggs have an operculum and are large • Symptoms – diarrhea, bowel obstruction, malabsorption, even death 4 -13
F. Buski (large intestinal fluke) adult • Adults are found in bile duct • Symptoms include • irritation, obstruction, enlarged liver, cirrhosis, anemia, diarrhea and cough 4 -14
F. Buski egg • Operculum • Large size • Embryo is undifferentiated 4 -15
F. buski egg • Eggs cannot be differentiated from those of F. hepatica 4 -16
F. hepatica F. buski 4 -17
F. hepatica F. buski 4 -18
Clonorchis sinensis (Oriental or Chinese liver fluke; Opisthorchis) Method of diagnosis Diagnostic stage Disease name Major pathology and symptoms Treatment Distribution 4 -19
Clonorchis sinensis – Chinese liver fluke 4 -20
Clonorchis sinensis • Adults – liver; bile ducts • Eggs in feces (DS) • Eggs hatch in fresh water • Larva invade snail ( Intermediate host #1) • Develop into cercariae ; leave snail • Invade freshwater fish ( Intermediate host #2) • Metacercaria encyst in muscle of fish • Humans ingest metacercaria (IS) in undercooked fish • Migrates to liver 4 -21
Clonorchis sinensis adult • Symptoms • Mild or no symptoms with light infection • Bile duct damage • Enlarged liver; jaundice • Abdominal pain; diarrhea; anorexia • Structures • • Oral & ventral sucker Uterus Vitelline branches along uterus testes 4 -22
Clonorchis sinensis egg 4 -23
Eggs can sometimes be recovered from bile ducts or drainage • Yellow-brown – stains from bile • Thick shell • Bell – shape • Operculum • Thickened opercular rim – “shoulders” • Polar knob opposite operculum 4 -24
Heterophyes heterophyes and Metagonimus yokogawai (Heterophyids) Method of diagnosis Diagnostic stage Disease names Major pathology and symptoms Treatment Distribution 4 -25
Heterophyes heterophyes and Metagonimus yokogawai (Heterophyids 4 -26
Heterophyes heterophyes and Metagonimus yokogawai (Heterophyids 4 -27
Paragonimus westermani (Oriental lung fluke) Method of diagnosis Diagnostic stage Disease name Major pathology and symptoms Treatment Distribution 4 -28
Paragonimus westermani Adult 4 -29
Paragonimus westermani egg 4 -30
Paragonimus westermani 4 -31
Schistosoma spp. (blood flukes) Method of diagnosis Diagnostic stages Disease names Major pathology and symptoms Treatment Distribution 4 -32
Schistosome – Male & Female Adults Mating 4 -33
S. Mansoni egg – Manson’s blood fluke Note the lateral spine 4 -34
S. Mansoni eggs 4 -35
S. japonicum egg – Oriental blood fluke very small lateral spine (knob) – may not be visible 4 -36
S. japonicum egg 4 -37
S. Haemotobium ( bladder fluke) Egg – note the terminal spine 4 -38
S. Haemotobium egg • Note the large terminal spine • eggs are usually found in urine, not feces • Can be associated with development of bladder cancer 4 -39
- Slides: 39