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1 The adult worm lives in theintestine ofhumans.

2 The larvae ( Cysticercus cellulosaebladder worm) localize in pigs mainly.

3 Cysticercus cellulosaecan also infect

humans causing cysticercosis.

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Morphology

Adult :2-4 m long,700-1000segments:Scolex

NeckImmature

segmentMature

segmentGravid segment

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MorphologyScolex: 1mm in diameter,

a rostellumarmed with two circles

of hooks.

( armed tapeworm)

four suckers

Neck:

The region for proliferation

rostellum

sucker

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Immature segment

note that thereproductive organsare just beginning todifferentiate.

(Carmine stained)

Developing reproductive organs

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Mature segments (proglottids)

Hermaphroditic

testes, sperm

ductovary, uterus

genital pore

vitellaria (yolk

gland)excretorycanal

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Mature segment

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Gravid segment

Note : Less than 14lateral uterine branches

(one side)

India ink stained

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Cysticercus cellulosae

Scolexcyst

The cyst is filled with fluid

http://www.cdfound.to.it/HTML/cyst6.htm

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Cysticercus cellulosae

It is soybean-likein shape, has ansmall scolex

invaginated intothe translucent cyst.

(left)

The scolex evaginatedfrom the cyst (right) Cysticercius cellulosae

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Cystcercus cellulosaein muscles of pigs

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Taenia saginata (beef tapeworm)

4-8 m ,

1000-2000segments

ScolexNeck

Immature

segment

Mature segment

Gravid segment

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Scolex and Neck

1.5- 2 mm indiameter

Without rostellumand hooks

Four suckers

( unarmed tapeworm)

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Mature segment (ovary with 2 lobes) Note : Bilobed ovary

(Carmine stained)

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Gravid segment India ink technique Note : More than 15 lateral

uterine branches (oneside).

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Cysticercius bovisShow invaginatedscolex

(left) show

evaginated sscolex(right)

The scolex is similar

tothat of adult worm in

morphology

Cysticercius bovis

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Cysticercus bovis

Cysticercus bovisshowing

the bladder

and

the scolex

(measly beef)

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Taenia eggs

The eggs of

Taenia saginata

and T. soliumareindistinguishable

morphologically.

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Taenia egg

spherical

31 to 43 m

a thick embryophore

an oncosphere inside

an egg shell outside

(usually break awayfrom the eggs in the

feces)

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Gravid segment

( the primary lateral branches of theuterus)

Taenia solium Taenia saginataThe uterus The uterus

has 7 to 13 has 15 to 30

lateral branches lateral branches

on each side on each side

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Life cycle of Taenia solium

Humans serve as final hosts as well as intermediate

hosts in the life cycle of Taenia solium.( both adult and bladder worm parasite in humans)

1 The adult worm lives in the small intestine of humans

( pork tapeworm infection)

2 The larvae (Cysticercus cellulosea, bladder worm )localize and develop in pigs (intermediate host)

3 The cysticercus cellulosae may also infect humanscausing cystcercosis (humans as intermediate hosts)

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Life cycle of Taenia saginata

The life cycle of Taenia saginata is similar tothat ofTaenia solium, but the intermediate

host is

cattle.

The custicercus bovis(the beef bladderworm )

nearly does not parasite in human body.

Humans serve as the final hosts only.

(beef worm infection)

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Humans are the only definitive hosts for Taenia

saginataand Taenia solium.

Eggs or gravid proglottids are passed with feces

The eggs can survive for days to months in the

environment.

Cattle (T. saginata) and pigs (T. solium) becomeinfected by ingesting eggs or gravid proglottids

In the animal's intestine, the oncospheres hatch ,invade the intestinal wall, and migrate to tissues,where they develop into cysticerci.

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A cysticercus can survive for several yearsin the animal.

Humans become infected by ingesting rawor undercooked infected meat.

In the human intestine, the cysticercusdevelops over 2 months into an adulttapeworm, which can survive for years.

The adult tapeworms attach to the smallintestine by their scolex and reside in thesmall intestine

The adults produce gravid proglottids

which detach from the tapeworm, andmigrate to the anus or are passed in thestool.

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Life cycle

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Geographic Distribution

Both species are worldwide in distribution.

Taenia soliumis more prevalent inpoorer communities where humans live in

close contact with pigs and eatundercooked pork, and in very rare inMuslim countries.

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Clinical Features

Taenia saginatataeniasis produces mildabdominal symptoms and may cause

malnutrition. (Epigastric pain, vomiting, diarrhea)

The most striking feature consists of the

passage (active and passive) of proglottids. The patients may find gravid proglottids

themselves and take the segments to seedoctors.

Occasionally, appendicitis or cholangitis canresult from migrating proglottids.

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Taenia soliumtaeniasis is less symptomatic

than Taenia saginatataeniasis.

The main symptom is often the passage

(passive) of proglottids.

The most important feature of Taenia solium

taeniasis is the risk of development ofcysticercosis.

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Laboratory Diagnosis Microscopic identification of eggs and

proglottids in feces is diagnostic fortaeniasis.

Repeated examination and concentrationtechniques will increase the likelihood of

detecting light infections.

Species determination of Taeniaisimpossible if solely based on microscopic

examination of eggs, because all Taeniaspecies produce eggs that aremorphologically identical.

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Eggs of Taeniasp. are also

indistinguishable from those produced bycestodes of the genus Echinococcus.

Microscopic identification of gravid

proglottids (or, more rarely, examinationof the scolex) allows species

determination.

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Summary on differentiations between the two

species of tapeworms

Feature T. soli um T. saginata

Body length 2-4m 4-8m

No. of segments 700-1000, thinner,

transparent

1000-2000, thicker,

untransparentScolex globular (1mm), with a

rostellum and hooks

pyriform (1.5 - 2mm),

without rostellum and

hooks

Mature

segment

trilobed ovary

( a small central lobe)

bilobed ovary

Gravid

segment

The uterus has 7-13 lateral

braches on each side

15-30 lateral branches on

each side

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Diagnostic findings Microscopy:

1 egg

* The eggs can not be

used as speciesidentification.

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2 scolex

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Differential Morphology of the Diagnosticstages of the two species: gravid segment

Species

(Gravid segment)

Size Appearance ofUterus

Other

Taenia solium 12 mm inlength x 5-7

mm wide

Central "stem"with 7-13 main

lateral brancheson each side.

Usually onsurface of fecal

material. Maybe in shortchains of 2-3proglottids.

Taeniasaginata 16-20 mm long5-7 mmwide.

Central "stem"with 15-30main lateralbranches oneach side.

Usually onsurface of fecalmaterial. May

be singledetachedproglottids

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gravid segment

The mostimportantdiagnostic stage ofthe two species

taeniasis.

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Antibody detectionmay prove useful

especially in the early invasive stages,when the eggs and proglottids are not

apparent in the stools.

Treatment:

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Treatment: Treatment is simple and very

effective. Praziquantel* is the drugof choice.

Cysticercosis

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Cysticercosis

Causal Agent:

The cestode (tapeworm) Taenia solium(pork tapeworm) is the main cause of

human cysticercosis.

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Life Cycle

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Cysticercosis is an infection of bothhumans and pigs with the larval stages of

Taenia solium.This infection is caused by ingestion of

eggs of a human tapeworm carrier.

Pigs and humans become infected by

ingesting eggs or gravid proglottids

Humans are infected either by ingestionof food contaminated with feces, or by

autoinfection.

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In autoinfection, a human infected withadult T. soliumcan ingest eggs eitherthrough fecal contamination or, possibly,from proglottids carried into the stomach byreverse peristalsis

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Once eggs are ingested, oncosphereshatch in the intestine , invade the

intestinal wall, and migrate to striatedmuscles, as well as the brain, liver, andother tissues, where they developinto cysticerci.

In humans, cysts can cause seriousresults if they localize in the brain,resulting in neurocysticercosis

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Clinical Features The symptoms of cysticercosis are caused by

the development of cysticerci in various sites.

Of great comcern is cerebral cysticercosis

(or neurocysticercosis), which can causemanifestations including seizuresmentaldisturbances, focal neurologic deficits, andsigns of space-occupying intracerebral

lesions. Death can occur suddenly

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Cerebral cysticercosis

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Extracerebral cysticercosis can causeocular, cardiac, or spinal lesions with

associated symptoms Asymptomatic subcutaneous nodules and

calcified intramuscular nodules can beencountered.

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Cysticercosis

Cysticercus cellulosaein heart

( Cardiac cysticercosis )

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Ocular cysticercosis

Patient may complain

of blurred vision evenblindness.

serious symptoms

usually occur after the

death of the cysticercus

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Laboratory Diagnosis The definitive diagnosis consists of

demonstrating the cysticercus in the tissueinvolved.

Persons who are found to have eggs orproglottids in their feces should beevaluated serologically since autoinfection,

resulting in cysticercosis, can occur.

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Diagnostic findings

Antibody detection provides a useful adjunctin specific diagnosis

Improved imaging techniques such as CTand MR can be very useful in detectingcysticerci in various organs .

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Antibody detection:

Sera from patients

with cysticercosisreact with at leastone of the specificproteins (left)

whereas sera frompatients withechinococcosis donot react with anyof the sevendiagnosticproteins.(right)

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TreatmentInfections are generally treated with anti-

parasitic drugsin combination with

anti-inflammatory drugs.

Surgeryis sometimes necessary to treatinfection in the eyes, cases that are notresponsive to drug treatment, or to reducebrain edema.

The use of albendazoleand praziquantelis

controversial.

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Summary

Organism Transmission Symptoms Diagnosis Treatment

Taenia

saginata

Measly beef Epigastric pain,vomiting,

diarrhea

Proglottids or

eggs in stool or

perianal areaPraziquantel

Taenia solium Measlypork

Epigastric pain,

vomiting,

diarrhea

Proglottids or

eggs in stool or

perianal areaPraziquantel

T. soliumCysticercosis

Oral-fecal Muscle painand weakness,

ocular and

neural

problems

CT , MR

antibody

detection

Praziquantelor

Albendazole