Cestodes Flashcards by Kyra Catedral

collectively called the______
dorsoventrally flattened
bilaterally symmetrical

Phylum Platyhelminthes

flatworms

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Platyhelminths are covered by a membrane called

tegument

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Platyhelminths are hermaphrodite except for

Schistosoma species

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Characteristics of Class Cestoda

Taenia species (example)
Adult worms are seen in the intestine
Proglottids contain male and female parts
Eggs have 6 hooked embryos
World-wide distribution
nO digestive tract, no circulatory system
Ribbon-like body, flat
Middle (intermediate host is required)

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Pseudophyllidea
2

● Diphyllobothrium latum

● Spirometra: S. erinacei ; S. mansoni ; S. ranarum

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Cyclophyllidea
5

Taenia solium and Taenia saginata
Hymenolepis nana and Hymenolepis diminuta
Dipylidium caninum
Raillietina garrisoni
Echinococcus granulosus

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T soium

Pork tapeworm

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CN
T saginata

Beef tapeworm

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T multiceps

Coenurus Tapeworm

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Echinococcus granulosus CN

Hydatid Tapeworm

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Echinococcus multilocularis CN

The Multiloculate or
Alveolar Hydatid Tapeworm

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Hymenolepis nana CN

Dwarf tapeworm

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Hymenolepis diminuta CN

Rat tapeworm

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Dipylidium caninum CN

Double-pored Tapeworm

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Diphyllobothrium latum CN

Broad Fish Tapeworm

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3 types of proglottid:

Immature
Mature
Gravid

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– undeveloped sexual organ, nearest to the neck

immature

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– fully mature sexual organ

mature

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– contains fertilized egg, undergoes apolysis

gravid

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Species of Class Cestoda

Species which require a vertebrate intermediate host

Taenia solium (pork tapeworm)
Taenia saginata (beef tapeworm)
Echinococcus granulosus (dogs, carnivores)

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Species of Class Cestoda

Species which require an invertebrate intermediate host

▪ Dipylidium caninum (dog tapeworm, double-pored tapeworm)

▪ Hymenolepis diminuta (rat tapeworm)

▪ Raillietina garrisoni (Tribolium confusum)

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Species of Class Cestoda

Species which may or may not require intermediate host

▪ Hymenolepis nana (dwarf tapeworm)

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Species of Class Cestoda

Species which infect man in their larval stages

▪ Diphyllobothrium latum

▪ Echinococcus granulosus (hydatid worm)

▪ Echinococcus multilocularis

▪ Taenia solium

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D latum

• Scolex is ____ shaped

• Scolex bears 2 slit-like grooves called_______ (1 on the dorsal surface and 1 on the ventral surface)

• Scolex has no ____ and ____

•_____ is thin and unsegmented and is much longer than the head

spoon-shaped or spatulate

bothria

no rostellum and no hooklets

Neck

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Morphology • 3,000 to 4,000 proglottids • A mature segment is filled with male and female reproductive organs • Terminal segments shrink and becomes empty as eggs are constantly discharged • Dried up segments break off from the body in chains and are passed out in the host’s feces • Uterus at the center of the segment appears in the form of a rosette

Diphyllobothrium latum

D latum Uterus at the center of the segment appears in the form of a___

rosette

D latum ova Bile stained or not?

Bile stained

Ova of _____ • 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 • About 1 million released everyday

D latum

D latum First stage larva • Ciliated oncosphere that develops from egg in water

Coracidium

D latum Second stage larva • Spindle-like solid body with cephalic invagination • Found inside the_____ (the first IH)

Procercoid cyclops

D latum Third stage larva • Head is invaginated in the neck • Found in the_____, the second IH

Plerocercoid fresh water fish

Diphyllobothrium latum • Definitive Host • Habitat

• Man, dog, cat Small intestine

D latum • 1 st I.H. • 2 nd I.H.

• Cyclops or Diaptomus • Fresh water fish, pike, trout, salmon, perch

D latum Mode of Infection

• Ingestion of imperfectly cooked infected fish or roe containing plerocercoid larvae

Diphyllobothrium latum • Diagnosis

• Microscopic examination of feces for the characteristic operculated eggs

T solium Color and length

whitish, creamy white, measures 3-5 meters

T saginata Color and length

white and semitransparent, measures 5- 10 meters

T solium # of segments

800 – 1000

T saginata # of segments

1000 – 2000

T solium scolex Armed or unarmed

Armed

T saginata scolex Aremd or unarmed

Unarmed

T solium Proglottids (Mature) with______

accessory ovary

T saginata ovary

No accessory ovary

Taenia solium Proglottids (Gravid) Branches

8 –12 lateral branches

Taenia saginata Branches

15-30 lateral branches

Taenia solium Apolysis

In chains

Taenia saginata Apolysis

Singly

Taenia solium

30, 000 t0 50, 000 eggs

T saginata # of eggs/gravid proglottid

80, 000 eggs

IH of solium and saginata

Swine/ pig and cow/ cattle

D latum Diagnosis Cysticercosis

Biopsy (subcutaneous nodule) X-ray/CT/MRI: cerebral cysticercosis Ophthalmoscopy: ophthalmic cysticercosis

D latum ( taeniasis) Taeniasis : to find egg at perianal region : to find segment (species identification)

Anal swab Fecal exam

Scolex • subglobular in shape with 4 cuplike suckers, has a retractable rostellum armed with single row of 20-30 Y –shaped hooklets • long and slender neck

Hymenolepis nana

Scolex club-shaped with 4 cuplike suckers, rostellum unarmed or devoid of hooks

Hymenolepis diminuta

Proglottids (Mature) • segment is narrow • one ovary more or less straight pattern across • 3 ovoid testes

H nana

Proglottids mature • segment is broad • bilobed ovary • 3 globular, widely separated unilateral genital pores

H diminuta

Proglottids ( Gravid Segment ) narrow, uterus is sac-like irregular • Testes and ovary disappear • Uterus hollows out and filled with eggs

Hymenolepis nana

Proglottids ( Gravid Segment ) • Sac like uterus filled with eggs • Disintegrate, release eggs into the feces

Hymenolepis diminuta

• 30-47 μm diameter polar filaments originating from polar knobs at either end of the embryopore • Polar filaments are 4-8 in number

Hymenolepis nana

• Has an inner membrane around the oncosphere which has 2 polar knobs but no polar filament • Fan-like hooklets • Bile stained

Hymenolepis diminuta

Hymenolepis nana Intermediate host

flea, beetle, cockroaches

H nana vs H diminuta Does not necessarily require an IH

H nana

Hymenolepis diminuta IH

flea, beetle, cockroaches, mealworms, earwigs

H nana vs H diminuta Requires an IH

H diminuta

Hymenolepis nana vs Hymenolepis diminuta Arthropod IH Rat flea - Dog flea - Human flea - Flour beetle -

Xenopsylla spp. Ctenophalides canis Pulex irritans Tribolium spp.

Hymenolepis nana vs Hymenolepis diminuta Diagnosis

• Demonstration of eggs in stool • Light infection: concentration of stool on alternate days • Stool exam repeated after 2 weeks

H nana vs H diminuta Are proglottids recovered?

Proglottids are not recovered - - - undergo degeneration prior to passage with stools

H nana vs H diminuta Is it possible for whole worm to be recovered

Yes At times whole worm is expelled

Which is bigger Dipylidium caninum vs Raillietina garrisoni

Raillietina garrisoni

Dipylidium caninum vs D caninum vs R garrisoni Scolex small with 4 deeply cupped suckers and a protrusible rostellum which is armed with 1- 7 rows of rose-thorn hooklets

D caninum

D caninum vs R garrisoni Scolex subglobular and is provided with 4 cuplike suckers with refractile rostellum armed with 2 alternating circular rows of 90-140 hammer shaped hooks

Raillietina garrisoni

Proglottids (Mature) • segment is narrow • double set of reproductive organs and a genital pore at each lateral margin

Dipylidium caninum

• With bilobed ovary and 36 – 50 ovoid testes • Genital pore opens on one side near the anterior lateral border of the segment

Raillietina garrisoni

Dipylidium caninum vs Raillietina garrisoni Proglottids (Gravid) • Pumpkin seed-shaped filled with capsules or pockets of 8 – 15 eggs enclosed in embryonic membrane

D caninum

D caninum vs R garrisoni Proglottids (Gravid) • 2 mm in length with 200-400 egg containing 1 –4 ***spindle shaped eggs*** • Enclosed in two membranes : outer – elongated inner – spherical • Segments – motile, white, “rice grain”

Raillietina garrisoni

Dipylidium caninum IH

Ctenocephalides canis = dog flea Ctenocephalides felis = cat flea Trichoedectes canis = dog louse Pulex irritans = human flea

Raillietina garrisoni IH

Tribolium confusum = flour beetle

Dipylidium caninum Diagnosis

• recovery of gravid segments • egg capsules are rarely passed-out in the feces

Raillietina garrisoni Diagnosis

• recovery of gravid segments • segment is glistening with rice grain appearance

Extra Intestinal Cestodes

Echinococcus granulosus Echinococcus multilocularis Spirometra mansoni Spirometra erinacei Spirometra ranarum

Scolex • bears a prominent rostellum with double row of 20 to 40 large and small hooklets

Echinococcus granulosus

Segments 3 segments • 1 immature • 1 elongated mature • 1 long gravid

Echinococcus granulosus

Ova • subspherical with a brown radially striated embryophore which cannot be differentiated from Taenia eggs

Echinococcus granulosus

Echinococcus granulosus • infective stage of the parasite • 20 cm in diameter • developing membrane is 2 layers

Hydatid cyst

E granulosus hydatid cyst • developing membrane is 2 layers:

1. outer laminated layer 2. inner nucleated germinal layer

- buds or capsules which contain protoscolices - free brood capsule and free scolices are referred to as “HYDATID SAND”

inner nucleated germinal layer

Hydatid cyst - milky opaque - non-nucleated layer

outer laminated layer

Echinococcus granulosus Life cycle DH: IH: AH:

dogs and other canines sheep, goats, swine man

Echinococcus granulosus Pathology: affects primarily the ____ and ____

liver and the lungs

Echinococcus granulosus Diagnosis

• Unilocular cysts ( only after they have grown to a tremendous size) • X-RAY • Exploratory cyst puncture • Immunologic test • Intradermal test • Precipitin test • CF • Hemagglutination • IHA, IFA, EIA

Echinococcus multilocularis Morpholgy: - Adult similar to_____ - 1.2 mm – 3.7 mm

E. granulosus

Echinococcus multilocularis Cyst has a thin outer wall that grows and infiltrates into surrounding host tissues. - Fluid filled pockets containing protoscolices - Break off and metastasize to other parts of the body forming _____ or ______

alveolar or multilocular hydatid cysts

Echinococcus multilocularis Diagnosis: Prevention :

- Radiological studies alveolar hydatidosis - ELISA - Deworming of dogs

Cestodes Flashcards

(93 cards)