Introduction To Cestodes PDF

Review Nematodes Elongate/cylindrical Alimentary canal present Sexes usually separate Life cycle direct or indirect L1 (mff) – L2 – L3 – L4 – L5 (immature adult) – adult – egg Survival methods Parasite of veterinary importance Phylum Nematoda (Roundworms) Phylum Platyhelminthes (Flatworms) – Class C...

Review Nematodes Elongate/cylindrical Alimentary canal present Sexes usually separate Life cycle direct or indirect L1 (mff) – L2 – L3 – L4 – L5 (immature adult) – adult – egg Survival methods Parasite of veterinary importance Phylum Nematoda (Roundworms) Phylum Platyhelminthes (Flatworms) – Class Cestoda (Tapeworms) – Class Trematoda (Flukes) Learning objectives Cestodes Know the key characteristics Be able to identify the final host (FH) and intermediate host (IH) Know the location of adults in the FH Know the clinical relevance in each host Know the “purpose” of adults and larvae Taenia solium – – Know who the final and intermediate hosts are Understand the significance of the wrong life stage in the wrong host Cestodes (tapeworms) Flat body without body cavity Strobila (body) with head, neck and proglottids (segments) Head: scolex with 4 suckers or bothria Hermaphroditic (each proglottid) No alimentary canal Indirect life cycle Several types of larval stages Cestodes (tapeworms) Photo: J. Ketzis Flat with “segments” Cestodes (tapeworms) Cyclophyllidea Scolex Cyclophyllidea One IH Organs of attachment associated with scolex and suckers Egg contains an oncosphere (http://phil.cdc.gov) Cestodes (tapeworms) Pseudophyllidea Two IHs (first a crustacean) Pseudophyllidea Bothria Organs of attachment associated with scolex and bothria Egg contains an oncosphere with cilia for motility (http://www.workforce.cup.edu/htm) Cestodes (tapeworms) Scolex – Suckers – Most rostellum – Armed or unarmed (hooks) Neck Strobila (body) – Proglottids (segments) – Mature posterior – furthest from the scolex Proglottid – Male and female reproductive organs – Vitelline glands – Genital pore Echinococcus granulosus adult scolex neck mature proglottid (RUSVM, 2006) Cyclophyllidea Cestodes Suckers – Shape – Size – Hooks Rostellum – Presence / absence – Hooks Copyright: Richard Fox, Lander University, http://lanwebs.lander.edu/faculty/rsfox/invertebrates/ Cyclophyllidea Cestodes -- scolex Photo: RUSVM Cyclophyllidea Cestodes -- scolex Photo: J. Ketzis Cyclophyllidea Cestodes -- scolex Cyclophyllidea Cestodes -- scolex Photo: J. Ketzis Cyclophyllidea Cestodes -- scolex Photo: J. Ketzis Cyclophyllidea Cestodes -- scolex Photo: J. Ketzis Cestodes (tapeworms) Proglottid – Shapte: width, length, fringe – A few or a lot – One or two genital pores – Position of glands Cestodes (tapeworms) -- Proglottids Cyclophyllidea Cestodes -- Proglottids Photo: J. Ketzis Cyclophyllidea Cestodes -- Proglottids Photo: J. Ketzis Cyclophyllidea Cestodes -- Proglottids RUSVM Cyclophyllidea Cestodes -- Proglottids Photo: RUSVM Cyclophyllidea Cestodes -- Proglottids Photo: J. Ketzis Cyclophyllidea Cestodes – glands and PORES Mature segments; reproductive organs Copyright: Richard Fox, Lander University, http://lanwebs.lander.edu/faculty/rsfox/invertebrates/ Cyclophyllidea Cestodes – glands and PORES Cestodes (tapeworms) Flat body without body cavity Strobila (body) with head, neck and proglottids (segments) Head: scolex with 4 suckers – Rostellum sometimes – Shape, size, hooks Proglottis – Hermaphroditic (each proglottid) – Shape, size, pores, glands No alimentary canal Learning objectives Cestodes Know the key characteristics Be able to identify the final host (FH) and intermediate host (IH) Know the location of adults in the FH Know the clinical relevance in each host Know the “purpose” of adults and larvae Taenia solium – – Know who the final and intermediate hosts are Understand the significance of the wrong life stage in the wrong host Cyclophyllidea Cestodes – life cycle Cyclophyllidea Cestodes – life cycle Adult in final host Segments (proglottids) in feces Eggs released from proglottids Eggs consumed by intermediate host Larvae develop in IH IH consumed by final host Adults rarely a problem unless heavy infection / young animals Larval stages, especially in humans, can cause damage Cyclophyllidea Cestodes – life cycle Cyclophyllidea Cestodes – life cycle Zajac and Conboy, 2012; Fig. 1.147 Cyclophyllidea Cestodes -- strobila Photo: Stephanie Bagwell Cyclophyllidea Cestodes – life cycle Segments release – Oncosphere – Hexacanth embryo Cyclophyllidea Cestodes – life cycle Dipylidium caninum Moniezia sp. Echinoccocus & Taenia spp. Photos: Zajac and Conboy, 2012 Cyclophyllidea Cestodes – life cycle Oncosphere / Hexacanth embryo consumed by an IH Forms a larva / larvae Purpose: make a scolex! Several types of larvae, but only one type occurs for each tapeworm species Cyclophyllidea Cestodes – life cycle Cyclophyllidea Cestodes – life cycle Clipart courtesy FCIT http://etc.usf.edu/clipart Cyclophyllidea Cestodes – life cycle http://www.adfg.alaska.gov/index.cfm ?adfg=disease.muscle1 Alaska Department of Fish and Game http://www.cfsph.iastate.edu/DiseaseInfo/cl inical-signs-photos.php?name=taenia Photo: Armed Forces Institute of Pathology Center for Food Security and Public Health at Iowa State University, College of Veterinary Medicine Taenia saginata cysticercus Hydatid cysts – Echinococcus sp. Photo: Thomas Nolan Hydatid cysts – Echinococcus sp. RUSVM Learning objectives Cestodes Know the key characteristics Be able to identify the final and intermediate host Know the clinical relevance in each host Know the “purpose” of adults and larvae Taenia solium – – Know who the final and intermediate hosts are Understand the significance of the wrong life stage in the wrong host Taenia solium Flat; hermaphrodites Final host – adult in intestine; clinical signs rare Proglottids in feces of final host Oncosphere – hexacanth embryo Intermediate host can have clinical signs Final host eats the IH Who are the hosts? Taenia solium Final host: Humans Intermediate host: Pigs Where are the proglottids? What do pigs eat? What do humans eat? Who has clinical signs? Taenia solium Final host: Humans – Consume larva by eating undercooked pork – Adult T. solium in the small intestine – Not normally pathogenic; Taeniasis; itchy rear end – Proglottids/Oncosphere in feces Intermediate host: Pigs – Consumes hexacanth embryo in human feces – Forms a larva (cysticercus) in muscle/tongue Taenia solium What if a person eats human feces? – Develops cysticercus – Can occur in brain: NCC neurocysticercosis Human is aberrant and deadend host when human has larval stage Taenia solium Taenia solium http://www.human-healths.com/wpcontent/uploads/2011/08/Taenia-solium4.gif Photos: CDC Taenia solium http://www.biology.ualberta.ca/parasites/ParPub/update/animate.htm Learning objectives -- Cestodes Know the key characteristics Be able to identify the final and intermediate host Know the clinical relevance in each host Know the “purpose” of adults and larvae Reminder: different larval stage depending on species Reminder: final host eats the IH Taenia solium – Know who the final and intermediate hosts are – Understand the significance of the wrong life stage in the wrong host