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

2. Phylum Platyhelminthes(Flatworms)Bilaterally symmetricalCompressed dorso-ventrallyHas a definiteanteroposterior axisThey lack a circulatorysystemSome species arehermaphroditic ormonoeciousSome are diecious 3. Possess a bilaterallysymmetrical excretorysystem, collectingtubules, and capillarieswhich terminate inflame cells. 4. Two classes under Phylum Platyhelminthes whichare of medical importance:a. Class Cestoideab. Class Trematoda 5. Class CestoideaCestodes or tapewormsinhabit the small intestinaltract of vertebrates while thelarva parasitize the tissues ofvertebrates and invertebrates.Adult cestodes are usuallyribbon or tape-like segmentedparasites varying in size froma few millimeters 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 cestodes include:1. the egg with a hexacanth embryoor oncosphere2. the larval stage (cysticercus,cysticercoid larvae, or coracidium,procercoid and plerocercoidlarvae)3. adult stageAll cestodes usually require anintermediate host although in somespecies the definitive host canserve as intermediate 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 TrematodaLeaf-like and unsegmentedAdult trematodes are providedwith an oral sucker and aventral sucker calledacetabulum.A third sucker called genitalsucker or gonotyl is observedonly among the heterophyids 9. The life cycle of trematodes includes:1. The egg stage2. The larval stages (miracidium, sporocyst, redia, cercaria,metacercariae)3. AdultThe definitive host (man) harbors the adult wormIntermediate host usually a freshwater snail or mollusk harbors thelarval stage2nd intermediate host (fish, crab, or another snail) is required forencystment 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