Supachai A. Basit, RMT, M.Bio.Ed.

Cestodes

1 S.A. Basit

Classification of Cestodes

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Order Pseudophyllidea. Scolex spatulate with bothria Diphyllobothrium latum

Order Cyclophyllidea. Scolex globular with four cuplike suckers

1. Species which require vertebtrate IH Taenia solium Tanenia saginata

2. Species which require invertebrate IH Diphyllidium caninum Hymenolepis diminuta

3. Species which may or may not require IH Hymenolepis nana

4. . Species which may infect man in their larval stages Echinococcus granulosus Echinococcus multilocularis Taenia solium

General Characteristics

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adults are ribbon-like or tape-like in appearance

sizes varies from few mm to several meterssegmentedhermaphroditicthe body consists of three regions:1.scolex2.neck3.strobila

Basic Parts of Cestodes

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Basic parts of a tapeworm

Classification of segments accdg to development

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immature segmentsmature segmentsgravid segments

Pseudophyllidea Cyclophyllidea

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spatulate with bothriauterine pore: presentgenital pore: centerno apolysisimmature

operculated ovaembryo: coracidium

(ciliated)2 IH2 larvae

1. procercoid larva2. plerocercoid larvae

globular scolex w/4 cup like suckers

uterine pore: absentgenital pore: sideundergoes apolysismature non

operculated ova 1 IH1 larva which could

be:- Cysticercus- Cysticercoid- Hydatid cyst

Pseudophllidea Cyclophyllidea

Diphyllobothrium latum

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Broad Fish tapeworm (Lumbricus latus, 1656)

DiphylobothriasisSparganosisunarmed scolex provided w/ bothriaadult worm is ivory white measures 3-10 m

or more and may have as many as 3,000 proglottids

Ova - operculated

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eggs are ovoidal, operculated, moderately thick-shelled, golden yellow, measures 58-76 by 40-51 um.

coracidium-ciliatedprocercoid-measures 550 um in length w/ 3

pairs of hookletsplerocercoid-measures 6 mm in length, no

scolex

Adult D. latum

Scolex and Proglottides

Mature segment with mature reproductive organs

Pathology: adult infection

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weakness, dizziness, abdominal discomfortfew suffers from “bothriocephalus anemia”pernicious anemia

Pathology: Larval Infection

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spargana maybe recovered from eye, nose, neck, brain, orbit

Sparganosis: 1.ingestion of infected cyclops containing

procercoid stage2.ingestion of raw infected flesh of

amphibians,reptiles,birds or mammals with sparganum

3.local application of the flesh of infected vertebrates to the skin

4.ingestion of raw pork

Sparganosis

Diagnosis, Treatment, Prevention and Control

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adult tapeworm infection is diagnosed by recovery of the eggs in stool

sparganosis- surgical removal Niclosamide and praziquantel against adult

D. latumPrevention includes thorough cooking of

freshwater fish and freezing of fish at –10 deg C for 24-48 hours.

Sparganosis can be prevented by boiling or filtering of water.

Taenia solium

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Pork tapeworm (verme solitario)Taeniasis soliumCysticercosisadult worm measurtes 2-3 m in lengthhead/scolex is globular in shape w/ 4 cup-shaped

suckersscolex-rostellum armed with ac double row of

hookletsegg is spherical, brown and measures 31-56 um in

diameterit has 2 radially-striated shells, inside the embryo

are 6 hooklets.the larval stage is called cysticercus cellulosae

T. Solium scolex

Scolex in electron micrograph

Taenia ova with hexacanth embryoOvum is striated

Cysticercus cellulosae: the larva and infective stage isolated from measly pork

Segment with <13 uterine branches

Pathology: adult infection

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presence of Taeniasis solium- brought about by ingestion of raw or

insuffeciently cooked pork containing cysticercus celluloseae.

- not so serious condition as compared to cysticercosis

Pathology: Larval Infection

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is quite serious it may affect the vital organsHuman cysticercosis or larval taeniasis- infection

with the larval stage caused by ingestion of eggs of T. solium or

through regurgitation of eggs and gravid segments of the

parasite into the stomach*Cysticercosis develops in the pig’s tissue and

the meat is termed “ MEASLY PORK”The pathology produced however by the larval

stage ( cysticercus cellulosae) is quite serious because it may lodge in the vital organs like brain, spinal cord, heart liver, eyes, etc.) giving rise to pressure symptoms.

Brain cysticercosis

Cysticercosis

Lab Dx

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demonstration of Taenia eggs in stoolT. solium is more pathogenic than T.

saginatasegments of T. solium- less than 13 uterine

lateral branchesas compared w/ T. saginata- more than 15 scolex: T. solium- w/ rostellum armed w/

spines T. saginata- neither rostellum nor spinescysticercosis: tissue biopsy (biopsy of

nodules)

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Treatment: Praziquantel, Niclosamide, Bithionol, Praziquantel, Paromomycin

Prevention:avoid eating insufficiently cooked pork

Taenia species

T. solium T. saginata

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armed scolex w/ rostellum

<13 uterine branches

IH: piglarva: cysticercus

cellulosaecysticercosispork tapeworm

unarmed scolex no rostellum

>15 uterine branches

IH: cattlelarva: cysticercus

bovisno cysticercosisbeef tapeworm

Taenia saginata

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Common name: “beef tapeworm” producing taeniasis saginata or beef tapeworm infection

Adult is whitish, opaque in color, and measures on the average of 5-10 min. in length---15m.

The worm is attached to the mucosa of the intestines by means of the scolex

IH: cattle, carabao, goats

Taenia saginata unarmed scolex without rostellum

Beef tapeworm mode of transmission

Actual length of beef tapeworm

Segment with genital pore

Pathology

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more dangerous to be infected by T. solium than with T. saginata because there seems to be no cysticercosis in man due to T. saginata.

pathology caused by this parasite is mainly due to its large size which is responsible in the disturbance in the normal functions of digestive tract.

Lab Dx

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stool exam using concentration techniquegravid segments passed out by the patient

can be pressed between two slides and lateral uterine branches counted.

Dipylidium caninum

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Common name: “ dog tapeworm” or double- pored tapeworm producing dipylidiasis

primarily a parasite of dogsbut man is ocassionally infected by

accidental ingestion of dog fleas containing the larvae

proglottids have double set of reproductive organs and a genital pore on each lateral margin

Scolex of dog tapeworm

Encapsulated ova of dog tapeworm

Pumpkin shape segment

Double-pored genital pore

Life cycle in dog

Actual size

Pathology

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degree of pathogenicity depends on intensity of infection

consists of slight intestinal disturbancesCommon tapeworm of dog and cat but man

is ocassionally infected by ingestion of dog fleas containing the larvae.

infection more common among children suggesting their greater exposure

Lab Dx, Treatment, Prevention and Control

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based on recovery of a single or chain groups of prolottids passed in the feces

eggs in egg capsule are seldom seen in feces

Quinacrine, niclosamidecats and dogs should be dewormed

periodically insecticide dusting of dogs and cats to kill

fleas

Hymenolepis diminuta

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Common name: “ rat tapeworm”scolex small, club-shaped with 4-cup-shaped

suckersmature segments of H nana and H diminuta are

hard to distinguishpathology: similar to other tapeworm infection recovery of characteristic eggs from patients

stooladult worms at times maybe expelled

spontaneouslyman is ocassionally infected through accidental

infection of invertebrae host. common parasite of rat, mouse and dog

Scolex

Ova of rat tapeworm

Ova

Cysticeroid larva

Immature segment

Mature segment

Gravid segment

Treatment, Prevention and Control

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Quinacrine, niclosamideeliminate rats and mice in housesdestruction of beetles, cockroaches and

other insects that act as intermediate host.

Hymenolepis nana

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dwarf tapeworm 0.5 to 9 cm; 96-840 segmentsscolex: minute; rhomboidal with 4 cup-

shaped suckers and a short rostellum armed with a ring of 20 to 30 spines

strobila: short, narrow proglottidsgravid: completely filled with eggseggs: spherical or subspherical hyaline

measures 30 to 47 um

Actual appearance

Ova

Scolex

Mature segment

Echinococcus granulosus

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Common name: hydatid worm producing unilocular echinococcus or hydatid disease

smallest tapeworm parasitizing man consisting only of a scolex, neck, and 3 segments

very rare infection in the Phil.common parasite of dogs, wolves, jackals,

coyotes, and other canines

Main parts of the worm

Scolex

Immature segment

Gravid segment

Pathology

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growing cyst lodged in vital organs like liver, lungs, brain, and heart interfere with the function of the organ.

uniocular cyst found in the bone is called osseous hydatid cyst

Worm in dog’s intestine

Liver with infected hydatid cyst

Hydatid cyst

Lab Dx

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unilocular cysts are diagnosed later in life only after they have grown to a tremendous size.

hydatid disease can be diagnosed by:

1.roentgenogram2.exploratory cyst puncture3.immunologic tests

Radiographic Examination

Treatment

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surgical removal of hydatid cysthuman infection results from fondling

infected dogsdogs should be prevented from eating

carcasses of sheep, cattle, and hogs in endemic areas

dogs should be dewormed periodically