Clinical Parasitology - 04 Cestodes

CLINICAL PARASITOLOGY GENERAL STRUCTURES CESTODES • OUTLINE • Cestodes o Introduction & Taxonomy o General Characteristics o General Structures o Pseudophyllidean & Cyclophillidean Cestode • Order Pseudophyllidea o Diphyllobotrium latum • Order Cyclophyllidea o Taenia Spp. o Hymenolepis Spp. o Dipyllidium Caninum o Echinococcus Granulosus o Echinococcus Multilocularis o Raillientina Garrisoni CESTODES INTRODUCTION AND TAXONOMY • • • • Order Pseudophyllidea o Diphyllobothrium latum/spinigerum Order Cyclophyllidea o Taenia solium o Taenia saginata o Hymenolepsis nana o Hymenolepsis diminuta o Dipylidium caninum o Echinococcis granulosis Scolex o Head part o Attachment organ ▪ Attach to small intestine linings o Shape: globular, pyriform, spoonlike (spatulate) ▪ Usually globular ▪ D. latum - only spatulate shaped scolex o Majority: with 4 cuplike suckers/grooves/acetabulum ▪ D. latum - only have 2 suckers o Recovery indicates success of treatment o Rostellum - fleshy extension of scolex (crown area) ▪ May be armed or unarmed ▪ Armed rostellum - contains hooklets ▪ Unarmed rostellum - no hooklets Neck o Region of growth ▪ Where germination process begin o Point of proliferation for the next set of segments Proglottids o Each segment o Strobila - chain of proglottids/segments o 3 types of Proglottids o Immature - nearest to the neck o Mature - middle portion, where reproductive structures are formed and found o Gravid/Ripe - farthest from the neck ▪ Filled with eggs (in the uterus) ▪ Can be detached through apolysis ▪ Gravid - filled with eggs GENERAL CHARACTERISTICS • • • • • • • • • • • • • Also known as ‘Tapeworms’ Flat/Ribbon-like White, yellowish in color Segmented Monoecious - hermaphrodite (contain both male and female genital) o Partially parthenogenic (not needing male to fertilize) o Can sometimes self-fertilize but most of time perform cross fertilization, requiring male No Gastrointestinal tract No Circulatory system With well-developed reproductive organs (testis, ovary, uterus) With Tegument outer covering of the worm o Serves as entry of nutrients and exit of wastes Habitat: Small Intestine Mode of Transmission: Oral route Eggs: non-operculated and mature (embryonated) except for D. latum Life Cycle: Egg → Larva → Adult PSEUDOPHYLLIDEAN & CLYCLOPHYLLIDEAN CESTODE Pseudophyllidean Species Diphyllobotrium latum Spirometra Scolex • Spoon spatula or almond shaped • With bothria (sucking grooves) • No hooklets (no rostellum) Strobila • Anapolytic (not shedding segments) • Segments have uterine pore and genital pore (centrally located) • • • • • Cyclophyllidean Taenia solium Taenia saginata Dipylidium caninum Hymenolepis nana Echinococcus granulosus Globular or pyriform shaped Quadrate (four cuplike suckers) With/without rostellum (w/ or w/o hooklets) Apolytic (shedding segments) Only genital pore is present (laterally located) Pseudophyllidean Gravid • All reproductive Proglottid structures are seen • Uterus - rosette-like appearance Notes • D. latum - only medically important • False tapeworms Ova Oval, opeculated, immature Larval 1st: Coracidium Stage/s 2nd: Procercoid 3rd: Plerocercoid/ Sparganum Cyclophyllidean • Only uterus can be seen o In different shapes/patterns • True tapeworms Hexacanth embryo/oncosphere spherical, nonoperculated, embryonated, w/ hooklets Cysticercus - T. solium/ saginata Cysticercoid - H. nana/ diminuta Hydatid - E. granulosus None to one intermediate host (lower form mammals or arthropods) Intermediate 2IH: Host 1st: Crustaceans (copepods, Cyclops) 2nd: Fresh water fishes Hosts 3 hosts (2 IH & 1 DF) 1 Host - DF 2 Hosts - 1 IH & 1 DF • • ORDER PSEUDOPHYLLIDEA Diphyllobotrium latum • • • • • • • • • • • Common name: broad fish tapeworm, fish tapeworm, broad tapeworm (according to Belizario de Leon) New name: Dibothriocephalus latus Largest tapeworm of man Habitat: small intestine Diagnostic stage: Egg/Scolex o Due to spatulate scolex Infective stage: Plerocercoid larva 1st IH: Copepods (cyclops, diaptomus) 2nd IH: Fresh water fish (small fishes) Paratenic host: Carnivorous fishes (larger size fishes) o Larger fishes consume smaller fishes o Man become definitve host by eating larger fishes Larval stages: Coracidium → Procercoid → Plerocercoid Mode of transmission: Ingestion Adult o Length: 3-5 meters to 10 meters o Mistaken with Spirometra ▪ Spirometra - found in canines/felines • Man become accidental host • Cause hearing loss in man o Scolex ▪ Spatulate/spoon/almond shaped ▪ With 2 bothrium (slit-slike sucking organ) o Uterus: rosette-like appearance o Strobila ▪ Up to 4000 proglottids ▪ Have uterine pore & genital pore • Centrally located o Largest cestode of man o Life span: 25 years Egg o 1 million ova/day o Unembryonated ▪ Becomes embryonated in water o Operculum on one end and terminal knob on the opposite (abopercular knob) o With underdeveloped coracidum o Mistaken with Paragonimus westermani PATHOLOGY • LIFE CYCLE Tapeworm/Bothriocephalus anemia (Diphyllobotriasis) o Adult may take up large amount of Vitamin B12 ▪ Vit. 12 - for RBC production ▪ Body cannot produce sufficient vit. B12 ▪ Body will not be able to produce enough RBC o Macrocytic, Megaloblastic anemia ▪ Macrocytic - Increase size of cells (RBC) ▪ Megaloblastic - increase size of immature cells (under lineage of RBCs) o Presence of megaloblastic cells in the circulation o Sometime demonstrates Pernicious anemia ▪ Macrocytic, megaloblastic anemia ▪ Impaired uptake of Vit. B12 from intestines ▪ Due to lack of cells producing intrinsic factors (IF) • IF - facilitate uptake of vit. B12 uptake from the intestines o Also produce gastric acids (HCl) in GI tract which may present achlorhydria o Achlorhydria - absence of gastric HCl LABORATORY DIAGNOSIS • • Stool Exam o DFS, Kato-katz o Look for Eggs or Scolex ▪ Due to unique structures Examination for Gastric Juice o Free hydrochloric acid o To differentiate Diphyllobotriasis from Pernicious anemia o Diphyllobotriasis ▪ Adult take over the function of IF by taking up large volume vit. B12 from intestine ▪ IF won’t have any vit. B12 to absorb for RBC to produce RBC o ▪ Presence of cell producing IF & gastric acid ▪ Presence of HCl Pernicious anemia ▪ Absence of HCl (achlorhydria) ▪ Lack of cells producing intrinsic factor (IF) and gastric acid (HCl) ▪ Cause macrocytic, megalobastic anemia Strobila TREATMENT & PREVENTION • • Gravid proglottids Treatment o Praziquantel - anti-parasitic Prevention o Proper cooking of fishes - 50°C for 10 minutes o Freezing of fishes - -18°C for 24-48 hours T. saginata T. solium 1000-2000 segments/proglottids 15-20 to 30 lateral branches (dichotomous/ treelike) with 97 to 104 thousand ova <1000 segments/proglottids 7-13 to 15 lateral branches (dendritic/ finger-like) With 30 to 50 thousand ova ORDER CYCLOPHYLLIDEA Length Taenia SPP. T. saginata T. solium Beef tapeworm Pork tapeworm Unhooked tapeworm Hooked tapeworm Small intestine Cattle, Cow, Camel Pigs and man Common Name Habitat Intermediate Host Larval Stage Cysticercus bovis Cysticercus cellulosae Infective Cysticercus bovis Cysticercus cellulosae Stage and embryonated egg Mode of Ingestion of measly Ingestion of measly pork Transmission beef w/ infective larva & embryonated egg Pathology Taeniasis saginata Taeniasis solium (due to adult); Cysticercosis (due to larva) Treatment Praziquantel, Niclosamide • Man - can contribute in development of T. solium • Measly - infective o o o o • • • Adult Scolex Egg o Spherical in shape o With striations o Embryonated when laid/passed out o With 6 hooklets in pairs o Motile ▪ Can be noted as first stage larva o Egg of Taenia spp. are indistinguishable ▪ Reported as Taenia spp. in lab reports o T. saginata adult - may lay 594,000 ova/year o PATHOLOGY LIFE CYCLE • 4-10 meters 7 meters (2-4 m) (up to 25 m) Lateral branches in gravid proglottids describe uterus T. saginata - longest tapeworm/cestode Segments are apolytic Drinking alcohol can irritate adult Taenia ▪ Irritating can result in shedding of proglottids T. saginata W/ 4 cuplike suckers No rostellum nor hooklets T. solium W/ 4 cuplike suckers W/ armed rostellum (2 rows of large & small hooklets) Taenia saginata – Taeniasis saginata o Non-specific symptoms: epigastric pain, hunger pangs, weakness, weight loss, loss of appetite, and pruritus ani o Intestinal obstruction due to tangled proglottids Taenia solium o Taeniasis solium – due to adult ▪ Non-specific symptoms: Abdominal discomfort, hunger, malabsorption o Cysticercosis – due to larva ▪ Accidental ingestion of egg ▪ More dangerous than Taeniasis solium ▪ Can spread to other organs (eyes, lungs, heart, brain) through bloodstream ▪ Ova may penetrate intestinal mucosa ▪ Neurocysticercosis • Migration and encysting of T. solium of larva in brain • most common parasitic disease of CNS • Most serious manifestation of cysticercosis • Headaches, seizures, confusion, ataxia, death LABORATORY DIAGNOSIS • • • • • Hymenolepis nana Stool Exam o Direct Fecal Smear, Concentration techniques o Look for eggs, proglottids, or scolex o Presence of eggs is intermittent o Sedimentation technique is preferred o Eggs are recorded as Taenia spp./ova Double Slide Compression Method o Sample: Gravid proglottids o Demonstration of lateral branches in the proglottids India Ink stain o Used to visualize the lateral branches in the proglottids of Taenia spp. o Black in color o Injected in genital pores o Genital pores - laterally located and connected to the uterus Perianal Swab o Eggs can be found in perianal region during shedding of proglottid o Recovery of Taenia ova/egg Infected person should observe proper hygiene Habitat Intermediate Host Final Host Larval Stage Infective Stage Mode of Transmission • H. nana o The only true human tapeworm o Most common cestode of man LIFE CYCLE • Adult H. nana H. diminuta Scolex Subglobular in shape W/ 4 cuplike suckers W/ 4 cuplike suckers W/ unarmed rostellum With retractable armed rostellum (single row of 20-30 Y shaped hooklets) Taenia asiatica • • • • • • • Other name: Taenia saginata asiatica Old name: Taiwan Taenia spp. Common name: Asian Taenia spp. Third specie of Taenia Closely resembles T. saginata Intermediate host: Pigs, cattle, goats, wild boar, monkeys Larval stage: Cysticercus viscerotropica OTHER Taenia SPP. Strobila Taenia multiceps Common Name Habitat Hymenolepis diminuta Small intestine Direct: N/A Arthopods (Grain Indirect: Rice/Flour beetle, flea, Beetles (Tribolium and cockroach, Tenebrio spp) Dog flea mealworms, earwigs, (Ctenophalides canis) myriapods, Human flea (Pulex lepidopterans) irritans) Rat flea (Xenopsylla cheopsis) Rat Man Man (accidental host) Cysticercoid larva Cysticercoid larva Direct: embryonated Cysticercoid larva ova (in man); Indirect: Cysticercoid larva Ingestion of Ingestion of embryonated cysticercoid larva ova/cysticercoid larva Taenia serialis 175-220 800-1000 segments/proglottids segments/proglottids Gravid Sac-like uterus filled with eggs proglottids Taenia Taenia brauni glomerata Bladder worm Eyes, Brain Subcutaneous Not known tissue Coenurus larva Larval stage Infective Eggs Stage Intermediate Sheep Rabbits Herbivores Hosts Final Host Canids Dogs, foxes Not known Accidental Man Host Mode of Ingestion of eggs in food, water, or fomites Transmission Pathology Human coenurosis • Multiceps multiceps - other name for T. multiceps • Coenurus larva - unilocular encysted larva; similar to cysticerosis • Human coenurosis - Usually caused by T. multiceps • Length 2-4 cm 20-60 cm o Proglottids are in craspedote form (overlapping) o H. nana - smallest cestode Ova H. nana H. diminuta Hooklets Three pairs Three pairs (hexacanth embryo) (hexacanth embryo) Polar Present (two polars) Present thickening Polar 4-8 polar filaments Absent filaments Embryophore Present (colorless) Present (colorless) Hymenolepis SPP. Common Name Hymenolepis nana Hymenolepis diminuta Dwarf tapeworm Rat tapeworm o H. diminuta - have sunny side/fried egg appearance Dipyllidium caninum • • • • • • • Common names: o Dog tapeworm o Double-pored tapeworm o Flea tapeworm o Cucumber tapeworm o Pumpkin seed tapeworm Habitat: Small Intestine Intermediate Hosts: o Dog louse (Trichodectes canis) o Dog flea (Ctenophalides canis) o Cat flea (Ctenophalides felis) o Human flea (Pulex irritans) Final Host: Dog Accidental Host: Man Larval Stage: Cysticercoid Infective Stage: Cysticercoid LIFE CYCLE LABORATORY DIAGNOSIS • Stool Examination o Eggs, Scolex, Proglottids Echinococcus granulosus • • • • • • • • • • • • Old name: Taenia granulosus Newer name: Echinococcus granulosus sensu lato o Collective term for several genotypes Common name: Hydatid worm, dog tapeworm, unilocular hydatid cyst Habitat: Small Intestine, connective tissue Intermediate Hosts: Sheep (Ox), Goat, Horse, Camel Final Host: Dog Accidental Host: Man Larval Stage: Hydatid cyst Infective Stage: o Final Host: Hydatid cyst (in dogs) o Intermediate host: Embryonated ova (in IH & man) Mode of Transmission: Ingestion of egg Pathology: Hydatid disease, Hydatidosis (echinococcosis) o Cystic echinococcosis Treatment: o Surgical removal of hydatid cyst o Albendazole, Mebendazole, Praziquantel LIFE CYCLE • • Adult o Length: 10-70 cm o Scolex: ▪ Globular ▪ With four suckers ▪ With armed rostellum (club-shaped) • 1-7 rows of rose thorn shaped hooklets o Proglottids: ▪ Double set of reproductive organs per segment ▪ Only parasite with 2 sets of reproductive organs o Gravid Proglottids: ▪ Melon/Pumpkin shaped ▪ With bilateral genital pore Egg o Spherical\ o Thin-shelled o With 6 hooklets (hexacanth embryo) o Similar with Taenia egg. o Enclosed in egg capsule/ egg packets ▪ 5-30 (8-15) embryonated eggs per packets o Largest ova of all cestodes due to egg packets • Adult o Length: 3-6 mm (4.5 mm) o Scolex: ▪ Pyriform ▪ With prominent armed rostellum (30-36 hooklets) o Proglottids: ▪ Only 3 segments • Immature, Mature, Gravid o Gravid Proglottids: ▪ Widest and longest proglottid ▪ With midline uterus o Shortest tapeworm of man • • Egg o Similar with Taenia egg Larva – hydatid cyst o Found in human tissue (mostly connective tissues) o Slow-growing, fluid-filled, tumor-like and space occupying structure o Enclosed with laminated germinative membrane o Brood capsule – found in the membrane where prostoscolices develops ▪ Prostoscolices - developing scolex o With Daughter cysts – miniaturized hydatid cyst inside the membrane o Hydatid sand – component of old E. granulosus larva ▪ Occur when brood capsule and daughter cysts disintegrate from main hydatid cyst/mother cyst which may cause liberation of prostoscolices ▪ Potentially toxic to man causing anaphylactic shock, death Raillientina garrisoni • • • • • • • LABORATORY DIAGNOSIS • • • • Roentgenogram (X-ray) o Look for bunch-of-grapes lesions Ultrasonography Immunologic test: o Bentonite Flocculation Test o Casoni Intradermal Test - injecting hydatid cyst extract and test for presence of antibodies against the hydatid cyst Exploratory Cyst Puncture: o An invasive procedure performed by physicians o Puncture the cyst o Aspirate the fluid o Inject prostoscolicidal (hypertonic solution causing rupture of brood capsule & daughter cysts) o Reaspirate burst fluid Echinococcus multilocularis • • • • • • • • • • • Common name: Alveolar hydatid worm Habitat: Liver, Lungs, Brain Intermediate Hosts: Rodents Final Host: Fox, Wolf Accidental Host: Man Larval Stage: alveolar hydatid cyst Infective Stage: Embryonated ova Mode of Transmission: Ingestion of egg Pathology: Alveolar hydatid disease o Fatal form of echinococcosis o Most lethal of all helminthic diseases o Cysts are formed in liver, lungs, brain Treatment: Albendazole, Mebendazole Morphology: similar with E. granulosis; indistinguishable in all stages Most common intestinal cestode of rodents in the Philippines. Infected patients appear asymptomatic Intermediate Host: Flour beetle (Tribolium confusum) Final Host: Rat Accidental Host: Man Larval Stage: cysticercoid larva Infective Stage: o Final Host: Cysticercoid larva o Intermediate host: Gravid proglottid LIFE CYCLE • • Adult o Length: 60 cm o Scolex: ▪ Subglobular ▪ With 4 suckers ▪ With prominent armed rostellum • Two alternating rows of 90 to 140 hammershaped hooks o Gravid Proglottids: ▪ Contains 200-400 egg capsules with one to four spindle-shaped eggs ▪ Rice-grain appearance Egg o Egg packets with 1-4 spindle-shaped ova