1. PHYLUMPLATYHELMINTHES:Tapeworms(flukes)Cestodes(tapeworms)by: Hannah Mae P. Sonido, RMT

2. Phylum Platyhelminthes(Flatworms) Bilaterallysymmetrical Compressed dorso-ventrally Has a definiteanteroposterior axis They lack a circulatorysystem Some species arehermaphroditic ormonoecious Some are diecious 3. Possess a bilaterallysymmetricalexcretory system,collecting tubules,and capillaries whichterminate in flamecells. 4. Two classes under Phylum Platyhelmintheswhich are of medical importance:a. Class Cestoideab. Class Trematoda 5. Class Cestoidea Cestodes or tapewormsinhabit the smallintestinal tract ofvertebrates while thelarva parasitize thetissues of vertebrates andinvertebrates. Adult cestodes are usuallyribbon or tape-likesegmented parasitesvarying in size from a fewmillimeters to severalmeters.The body consists of 3 distinctregions:Proglottids or segment:a. Immmature- no welldeveloped organsb. Mature- w/ well developedorganc. Gravid/ripe- filled with eggs 6. The life cycle of cestodesinclude:1. the egg with a hexacanthembryo or oncosphere2. the larval stage (cysticercus,cysticercoid larvae, orcoracidium, procercoid andplerocercoid larvae)3. adult stageAll cestodes usually require anintermediate host although insome species the definitivehost can serve asintermediate host. 7. Two orders of tapeworms with medical importance:OrderPSEUDOPHYLLIDEAOrderCYCLOPHYLLIDEAFalse tapeworm True tapewormexample D. latum All except D. latumscolex Spoon-shaped with slit-likesucking grooves calledbothriaWith 4 cup-like suckersstrobila Anapolytic (dont shedsegments)Apolytic (shed segments)ova Operculated, immaturewhen laidNon-operculated,embryonatedLarval stages 1st: coracidium2nd: procercoid3rd: plerocercoid (IS)1st: cysticercus2nd: cysticercoid3rd: hydatidIntermediate host 2 1 only 8. Class Trematoda Leaf-like andunsegmented Adult trematodes areprovided with an oralsucker and a ventralsucker called acetabulum. A third sucker calledgenital sucker or gonotylis observed only amongthe heterophyids 9. The life cycle of trematodes includes:1. The egg stage2. The larval stages (miracidium, sporocyst, redia, cercaria,metacercariae)3. Adult The definitive host (man) harbors the adult worm Intermediate host usually a freshwater snail or molluskharbors the larval stage 2nd intermediate host (fish, crab, or another snail) isrequired for encystment 10. Phylum PlatyhelminthesClass: Cestoidea (tapeworms)Subclass: CestodesOrder: Pseudophyllidea scolex spatulate with bothria1. Diphyllobothrium latumOrder: Cyclophyllidea- scolex globular with 4 cuplike suckersA. Species which requires vertebrate intermediate hosts1. Taenia solium2. Taenia saginataB. Species which require invertebrate intermediate hosts1. Dipyllidium caninum2. Hymenolepis diminutaC. Species which may or may not require intermediate host1. Hymenolepis nanaD. Species which may infect man in their larval stages1. Echinococcus granulosus2. Echinococcus multilocularis 11. Class: Trematoda (flukes)A. Species which inhabit the portal blood stream of vertebrates1. Schistosoma japonicum2. Schistosoma mansoni3. Schistosoma haematobiumB. Species which inhabit the liver of vertebrates1. Fasciola hepatica2. Clonorchis sinensis3. Opistorchis felineusC. Species which inhabit the small intestines of vertebrates1. Fasciolopsis buski2. Echinostoma ilocanum3. Heterophyid groupD. Species which inhabit the lungs of vertebrates1. Paragonimus westermani 12. CESTODES 13. Intestinal CestodesTaenia saginata Taenia soliumCommon name Beef tapeworm Pork tapewormIntermediate host cattle Pigscolex No rostellum Armed rostellumlength