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Classification of cestodes
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- 2. General Characteristics • Long,segmented and tape-like are called tapeworms • Dorso-ventrally flattened • Size varies from a few mm to several meters • Adult worms are found in the human intestines • There are 3 regions in an adult worm: • Head: scolex • Neck • Strobila (body or trunk) » Consist of a series of segment called proglottids
- 4. Segments of theStrobila • Immature: male and female organs are not differentiated • Mature: male and female organs have become differentiated • Gravid: uteri are filled with eggs
- 5. Other Characteristics • Sexesare not separate • Body cavity is absent • Alimentary canal is entirely absent • Excretory and nervous systems are rudimentary • Reproductive system is present and complete in each segment
- 6. I. Pseudophyllidean cestodes •Possess false or slit-like grooves called bothria • Adult worms in Intestine » Diphyllobothrium latum: Fish Tapeworm • Larval stages: Plerocercoid in Man » Sparganum mansoni » Sparganum proliferum Classification of Cestodes Infecting Man
- 7. • II. Cyclophyllideancestodes • Possess cup-like and round suckers called acetabula • Adult Worms in the Intestine » Taenia saginata » Taenia solium » Hymenolepis nana » Hymenolepis diminuta » Dipylidium caninum Classification of Cestodes Infecting Man
- 8. • According toHabitat • II. Cyclophyllidean cestodes • Possess cup-like and round suckers called acetabula • Larval Stages in Man » Hydatid cyst of Echinococcus granulosus and Echinococcus multilocularis » Cysticercus cellulosa of Taenia solium Classification of Cestodes Infecting Man
- 9. Differences Between aPseudophyllidean and a Cyclophyllidean Cestode Pseudophyllidean Cyclophyllidean Head or scolex Bears 2 slit-like grooves Bears 4cup-like suckers uterus No branching Convoluted uterine tubes Branching Uterine pore present absent Common genital pore Ventral; in the midline lateral eggs Operculated; gives rise to ciliated larvae Not operculated; do not give rise to ciliated larvae
- 10. Order Pseudophyllidea Characteristics • Largeworms consisting of a long chain of segments • “head” has two slit-like sucking grooves called bothria instead of suckers • Eggs are operculated and can develop only in water; oncosphere gives rise to ciliated embryo • Larval development proceeds in two intermediate hosts: • First larval stage is called procercoid • Second larval stage is called plerocercoid
- 11. Diphyllobothrium latum • CommonName: • Fish Tapeworm • Broad Tapeworm • Morphology • Adult worm is ivory color • Dark central markings in the strobila are due to the egg-filled uterus • Measures 3 to 10 meters in length • Life-span is for a period of 5 to 15 years
- 12. Diphyllobothrium latum • Scolexis spoon-shaped • Scolex bears 2 slit-like grooves called bothria (1 on the dorsal surface and 1 on the ventral surface) • Scolex has no hooklets • Neck is thin and unsegmented and is much longer than the head
- 13. Diphyllobothrium latum • Morphology •3,000 to 4,000 • A mature segment is filled with male and female reproductive organs • Gravid segments filled with eggs and break off thus passed out in faeces • Uterus at the center of the segment appears in the form of a rosette
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- 15. Diphyllobothrium latum Eggs • Passedout in the host’s feces in large numbers • Oval • Bile stained • Contains abundant granules and unsegmented ovum • Inconspicuous operculum at one end and a small knob at the other end • Does not float in saturated solutions of common salt • A single egg gives rise to a single larva • Not infective to man
- 20. Diphyllobothrium latum • larva •Passed first in water and then in the respective intermediate hosts • 3 stage – First stage larva » Coracidium » Ciliated oncosphere that develops from egg in water – Second stage larva » Procercoid » Spindle-like solid body with cephalic invagination » Found inside the cyclops (the first intermediate host) – Third stage larva » Plerocercoid » Head is invaginated in the neck » Found in the fresh water fish, the second intermediate host
- 21. Lab Diagnosis • Diagnosis •Wet mount Examination of faeces • Identifying the characteristic proglottids and operculated eggs • Treatment • Praziquantel: 5-10 mg/kg single dose for children and adults • Niclosamide not available locally
- 22. Sparganosis • The diseasecaused by pleurocercoid larva of spirometra is called as sparganosis
- 25. Clinical Features • Migratingspargana cause various symptoms depending on location in the host. • Spargana may locate anywhere • Migration in subcutaneous tissues is painless • In brain or spine can cause weakness, headache, seizure, and abnormal skin sensations, such as numbness or tingling • If Inner ear is involved, vertigo or deafness. • Sparganum proliferum can cause proliferative lesions in the infected tissue, with multiple plerocercoids present in a single site.
- 27. Laboratory Diagnosis • Recoveryof a sparganum from infected tissue. • To identify the species by infecting definitive host with a living sparganum and identify the adult after maturation.
- 28. Treatment • Surgical removalis the treatment of choice for sparganosis.