Introduction of Cestodes (Tapeworms) Phylum Platyhelminthes Class Cestoda Order Pseudophyllidea Order Cyclophyllidea

Morphology Flat, segmented body with various length (several mm ~ several meters) 3 regions of worm body: Scolex: suckers, hooklets, grooves Neck: germinal portion Strobila: immature, mature, gravid proglottids (segments)

Monoecious (each segment): reproductive system highly developed Digestive system degenerated All species are parasitic

Tapeworms

Taenia solium Taenia saginata 链状带绦虫 Pork tapeworm / Hook tapeworm 猪肉绦虫/有钩绦虫 Taenia saginata 肥胖带绦虫 Beef tapeworm / Hookless tapeworm 牛肉绦虫/无钩绦虫

Morphology T.saginata T.solium Size 4-8 m 2-4 m Scolex 4 suckers rostellum & hooklets Mature proglottid Ovary 2 lobes 3 lobes Testes 300-400 150-200 Gravid proglottid: Uterine branches 15-30 7-12

Taenia spp. (saginata and solium), adult worm: the chain of proglottides is called the strobila, and may be composed of over 1.000 proglottides. T.saginata may measure 9 m, whereas T.solium may reach 6 m Taenia spp. adult worm The chain of proglottids is called the strobila, and may be composed of over 1.000 proglottids. T.saginata may measure 9 m, whereas T.solium may reach 6 m.

The beef tapeworm (Living specimen) 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm The beef tapeworm (Living specimen)

The scolex of T. solium hooklets rostullum suckers The scolex of T. solium (show here) has four suckers and an armed-rostellum. The scolex of T. saginata looks similar but lacks hooks. These two species can be differentiated by counting the number of uterine branches in the proglottids; T. solium has between 7 to 13 per side, while T. saginata has 15 to 20. 来源 http://www.udel.edu/medtech/dlehman/mt372/Taenia.html The scolex of T. solium

The scolex of T. saginata Taenia saginata Adult-scolex 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm The scolex of T. saginata

Taenia saginata, fresh specimen . Note : Four suckers, no rostellum 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Taenia saginata, fresh specimen

Gravid proglottid of T. solium Gravid proglottid, India ink technique. Taenia solium Note : Less than 14 lateral uterine branches (one side). 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Gravid proglottid of T. solium

Gravid proglottid of T. saginata Taenia saginata Gravid proglottid , India ink technique. Note : More than 14 lateral uterine branches (one side). 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Gravid proglottid of T. saginata

Larva Cysticercus bovis Cysticercus cellulosae Ovoid, cystic, size = a bean Invaginated scolex and neck

T.solium: cysticercus cellulosae with invaginated scolex 来源 http://www.cdfound.to.it/html/taen1.htm Courtesy of Dr. Dan Steriu.  Head of Parasitology Laboratory,  Cantacuzino Institute Spl. Independentei.  103 sect. 5 Bucuresti 70 100, Romania. T.solium: cysticercus cellulosae with invaginated scolex

Egg Indistinguishable in two species Ovoid < Ascarid egg Radically striated embryophore Content: hexocanth embryo (oncosphere: 6 hooklets)

Can not differentiate T. saginata from T. solium Wet mount. Note : Brown, striated embryophore. Can not differentiate T. saginata from T. solium 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Taenia spp. egg Can not differentiate T. saginata from T. solium

Taenia spp. egg Wet mount. Note : Brown, striated embryophore. Can not differentiate T. saginata from T. solium 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Taenia spp. egg

Life Cycle Definitive host Discharged stage Human being; No reservoir host Discharged stage Eggs or gravid proglottids in feces

Life cycle of Taenia saginata Life cycle of Taenia saginata Humans are the only definitive hosts for Taenia saginata.  The adult tapeworms (length: usually 5 m or less, but up to 25 m) reside in the small intestine, where they attach by their scolex.  They produce proglottids (each worm has 1,000 to 2,000 proglottids), which mature, become gravid, detach from the tapeworm, and migrate to the anus or are passed in the stool (approximately 6 per day).  The eggs contained in the gravid proglottids (80,000 to 100,000 eggs per proglottid) are released after the proglottid becomes free and are passed with the feces.  The eggs can survive for months to years in the environment.  Cattle and other herbivores become infected by ingesting vegetation contaminated with eggs (or proglottids).  In the animal's intestine, the eggs release the oncosphere, which evaginates, invades the intestinal wall and migrates to the striated muscles, where its develops into a cysticercus.  The cysticercus can survive for several years in the animal. Humans become infected by ingesting raw or undercooked infected meat.  In the human intestine, the cysticercus develops over 2 months into an adult tapeworm, which can survive for more than 30 years. http://www.dpd.cdc.gov/DPDx/HTML/ImageLibrary/S_Listing_il.htm Life cycle of Taenia saginata

Life cycle of Taenia solium Life cycle of Taenia solium The life cycle of Taenia solium is similar to that of T. saginata.  The adults (length 2 to 7 m; less than 1,000 proglottids, which are less active than in T. saginata, and each with 50,000 eggs; longevity up to 25 years) develop not only in humans but also some other animal species (monkeys, hamsters).  The cysticercus develops not only in striated muscle, but also in the brain, liver, and other tissues of pigs and other animals, including humans.  Humans develop taeniasis when they ingest undercooked pork meat containing cysticerci.  They develop cysticercosis by ingesting T. solium eggs, either by ingestion of fecally contaminated food, or by autoinfection.  In the latter case, a human infected with adult T. solium ingests eggs produced by that tapeworm, either through fecal contamination or, more arguably, from proglottids carried into the stomach by reverse peristalsis. http://www.dpd.cdc.gov/DPDx/HTML/ImageLibrary/S_Listing_il.htm Life cycle of Taenia solium

Tissue(brain, eye, skin etc.) T.saginata T.solium D.H Human I.H Cattle Swine Habitation Small intestine Tissue(brain, eye, skin etc.) Infective stage Cysticercus bovis Cysticercus Cellulosae Egg Disease Taeniasis Cysticercosis

Pathogenesis Taeniasis ( Infected by eating cysticerus; Pathogenic factor: adult worm) Deprivation of nutrition Disfunction of the intestine: vomiting or diarrhea Allergic reactions Appendicitis Obstructions of the intestine

Cysticercosis (Intrinsic or extrinsic auto-infection; Cross infection due to T.solium egg only; Pathogenic factor: cysticercus cellulosae) Symptoms vary with site & intensity of infection Clinical aspects: headache, dizziness, epilepsy, blurred vision, subcutaneous nodule etc

Diagnosis Taeniasis Cysticercosis Anal swab: to find egg at perianal region Fecal exam: to find segment (species identification) Cysticercosis Biopsy (subcutaneous nodule) X-ray/CT/MRI: cerebral cysticercosis Ophthalmoscopy: ophthalmic cysticercosis

Epidemiology Distribution Cosmopolitan In china: mainly in minority regions

Epidemic factors Egg or gravid proglottid contamination of grass and soil Method of raising domestic animals Unhygienic dinning habit of eating raw or undercooked meat

Control Treatment Scientific cattle and pig raising Paziquantel Areca nut + pumpkin seed+ purge Scientific cattle and pig raising Avoid to consume raw meat Meat inspection

Echinococcus granulosus 细粒棘球绦虫/包生绦虫

Morphology Adult worm Egg 3-6 mm long with 4 segments Scolex & cervical portion (2 rows of 28-40 hooklets and 4 suckers) Immature, mature, gravid segments Egg Similar to the Taenia egg

Adult of Echinococcus granulosus 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Adult of Echinococcus granulosus

Hydatid cyst Round & cystic Cyst wall: laminated layer, germinal layer Contents: cystic fluid, brood capsules, protoscolex, daughter & grand daughter cyst, (hydatic sand)

Hydatid sand The protoscoleces generally settle down at the bottom of the cyst and are known as hydatid sand.

Protoscoleces with double row hooklets and calcareous corpuscles Protoscolices with double row hooklets and calcareous corpuscles. 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Protoscoleces with double row hooklets and calcareous corpuscles

Protoscolices with double row hooklets and calcareous corpuscles. 来源 http://www.medicine.cmu.ac.th/dept/parasite/official/cestode/frame_tr.htm Protoscoleces

"Hydatid sand".  Fluid aspirated from a hydatid cyst will show multiple protoscolices (size approximately 100 µm), each of which has typical hooklets.  The protoscolices are normally invaginated (left), and evaginate (middle, then right) when put in saline.  Image contributed by Georgia Division of Public Health. 来源 http://www.dpd.cdc.gov/DPDx/HTML/ImageLibrary/Echinococcosis_il.htm Hydatid sand

Life Cycle Adult worm Larva (hydatid cyst) In the small intestine of the dog and other carnivores Larva (hydatid cyst) In the tissue of human being, sheep, horse, pig, etc.

The adult Echinococcus granulosus (3 to 6 mm long) 1 The adult Echinococcus granulosus (3 to 6 mm long) 1.resides in the small bowel of the definitive hosts, dogs or other canids.  Gravid proglottids release eggs 2. that are passed in the feces.  After ingestion by a suitable intermediate host (under natural conditions: sheep, goat, swine, cattle, horses, camel), the egg hatches in the small bowel and releases an oncosphere 3. that penetrates the intestinal wall and migrates through the circulatory system into various organs, especially the liver and lungs.  In these organs, the oncosphere develops into a cyst 4. that enlarges gradually, producing protoscolices and daughter cysts that fill the cyst interior.  The definitive host becomes infected by ingesting the cyst-containing organs of the infected intermediate host.  After ingestion, the protoscolices 5. evaginate, attach to the intestinal mucosa 6. , and develop into adult stages 1. in 32 to 80 days.  The same life cycle occurs with E. multilocularis (1.2 to 3.7 mm), with the following differences: the definitive hosts are foxes, and to a lesser extent dogs, cats, coyotes and wolves; the intermediate host are small rodents; and larval growth (in the liver) remains indefinitely in the proliferative stage, resulting in invasion of the surrounding tissues.  With E. vogeli (up to 5.6 mm long), the definitive hosts are bush dogs and dogs; the intermediate hosts are rodents; and the larval stage (in the liver, lungs and other organs) develops both externally and internally, resulting in multiple vesicles.  E. oligarthrus (up to 2.9 mm long) has a life cycle that involves wild felids as definitive hosts and rodents as intermediate hosts.  Humans become infected by ingesting eggs 2. , with resulting release of oncospheres 3. in the intestine and the development of cysts 444444 in various organs. 来源 http://www.dpd.cdc.gov/DPDx/HTML/ImageLibrary/Echinococcosis_il.htm

Infective stage: egg Infective route: mouth Location: liver, lung, brain, eye, kidney, muscles, bone and heart Zoonotic parasite

Pathogenesis ‘Echinicoccosis’, ‘Hydatidosis’ Depend on the location and the number of hydatid cysts Pressure: liver, pulmonary, etc Allergy: anaphylactic shock Regeneration: secondary infection

Epidemiology Distribution Forest type (human are seldom involved) Wolf-moose/reindeer Dingo-wallaby Animal raising type (human are involved) Dog-sheep/cattle/pig

Endemic factors High resistant egg Intimate contact between dog, animals and man in local district Contamination of the feces by infected dogs Improper the viscera disposition

Diagnosis Physical (hepatic hypertrophy) History of residence in endemic area X-ray/Ultrasonography Immunological means Biopsy and puncture are forbidden unless during operation

Treatment and Control Surgical removal of the cyst Long-term Mebendazole therapy 40 mg/kg/day × 1-6 months Personal protection Reasonable disposition of the viscera from infected animals Treatment of sheep dogs periodically

来源 http://www.cdfound.to.it/html/echi1.htm