Phylum: Platyhelminthes (Flatworms)

1-Cestoda (tape worms).2-Trematoda (flukes).

Cestoda (tape worms)A) Intestinal adult tapeworms.

B) Extra-intestinal larval tapeworms.

Class: Cestoda (Tape worm)

1- The length of the different species varies from 3mm to 10 meters.

2- Segmented body: The body of the typical cestode consists of 3 distinct regions: scolex, neck, and strobila

3- Scolex (head) provided with suckers, sometime hooks.

4- Hermaphroditic mature segment has male and female reproductive system

5- Despite the lack of a digestive system (no mouth, no gut, no anus) they do absorb food from the hosts intestine

1- The size 3mm – 10 m.

General Morphology

• The body of the typical cestode consists of 3 distinct regions:

• scolex

• neck

• strobila

Form and Function: The Scolex cont.• The scolices of tapeworms are typically categorized as either acetabulate or bothriate, depending on the type of sucker present• An acetabulate scolex is characterized by the presence of 4 muscular cups sunk into the equatorial surface of the scolex; cups are radially arranged equidistant from each other

• In addition to muscular cups, there may be accessory holdfast structures, such as hooks to help anchor the scolex to the host’s intestinal wall

• In this case, the scolex is called an armed scolex• These hooks are usually grouped at the apical end of

the scolex on a protrusible rostellum

rostellum

Scolex: is located at the anterior end and functions as an attachment

structure 4 suckers hooklets: These hooks are usually grouped at the apical

end of the scolex on a protrusible rostellum

Neck• The neck is an unsegmented, poorly differentiated region

immediately posterior to the scolex• short measuring 5 to 10 mm in length

The StrobilaThe Strobila• As new proglottids are formed from the neck region, they

push the older ones progressively posteriad, creating a chain of proglottids - the strobila

• The asexual process of forming segments is termed strobilation.

The stroblia can be loosely subdivided into 3 regions:

Immature Mature Gravid proglottids

mature segment contain testes and ovary

gravid proglottid has a median uterus filled with eggs (50 – 80 000)

Larval (metacestoda):1- The larval are extracellular parasites,

visible to the naked eye, seen as bladders with an scolex.

2- The external surface is a tegumentary tissue, similar to that found in the adult worm.

3- In human infection, these larvae can survive for a many years.

4- Dead parasite tissue, leaving a calcified in both muscle and brain tissue.

Classification of Cestoda

Intestinal adult tapeworms.

Taenia solium Taenia saginata Taenia multicepsis Hymenolepis nanaHymenolepis diminuta Dipylidium caninumDiphyllobothrium latum

Extra-intestinal larval tapewormsEchinococcus granulosusEchinococcus multilocularis

Taenia solium (pork Tapeworm)

Taenia soliumCommon name: The Pork Tapeworm.Habitat: Small intestine.Route of infection: Eating of unwell cooked

Pork meat.Definitive host : Human.Intermediate host: Pork, Human (occasional).Infective stage: Cysticercus larvae (Pork).Diagnostic stage: Eggs or gravid in Feces.Disease: Adults cause: Taeniasis. Larvae cause:

Cysticercosis( presences of Cysticercus larvae in brain and muscles.

Taenia solium Adult worm1- 2-4 meters in length)2- Head or scolex globular in shaped with 4 suckers rounded rostellum armed with double rows of large and small hooks numbering 22 to 36.3- Neck

short measuring 5 to 10 mm in length.

Proglottids

Numbers : 700 to 1000 proglottidsComposed of:1- Immature proglottid 2- Mature proglottid: nearly square

containing full set of functioning male and female reproductive organs

3- Gravid proglottidlonger than broader consists: gravid uterus with 3 to 13 lateral uterine

branches arranged.

Mature proglottid Gravid proglottid

EggShape – sphericalSize: 30-40 um in diameter radially-striated shells Outer shell – thin and rarely seen Inner shell brown, thick and striated embryo or oncosphere with six hooklets

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Larval stage or bladder wormalso called Cysticercus cellulosaemeasurement – 5 to 10 mm in length and 5 mm in diameter scolex hooks suckers.

EPIDEMIOLOGY T. solium infectionHuman infected (raw or undercooked pork) Man is the only definitive host and the pig appears to be the only intermediate hostMan become the intermediate host Can be

caused by: ingestion of eggs from contaminated food or

waterby internal autoinfection when the eggs are

carried by reverse peristalsis back to the duodenum or stomach

Pathology 1- By adult in lumen of the small intestines : intestinal obstruction abdominal pain Vomiting . nausea weight loss and diarrhea.

2- By larval stage (cysticercus) Symptoms depend on location and number of larva, which encyst in the muscle and other tissues :

a. cellular reactions b. fibrosis c. necrosis cysticercosis in the brain may cause: a. epilepsy b. meningitis, and encephalitis Eye – cause blindness

Symptoms depend on location and number of larva

Diagnosis: 1-Adult worms: Taenia infections are diagnosis by finding gravid

segments in the feces, because their eggs are identical.

2- Cysticercosis: A- Serologic tests ELISA. B- X-rays may reveal calcified cysticerci. C- CT scan can show living cysticerci.

Taenia saginataBeef Tapeworm.

Taenia saginataCommon name: The Beef Tapeworm.Habitat: Small intestine.infection: Eating of unwell cooked cow meat.Definitive host : Human.Intermediate host: Cows also other herbivores.Infective stage: Cysticercus larvae.Diagnostic stage: Eggs and gravid in Feces.Disease: Adults cause Taeniasis.

Taenia solium Taenia saginata

Intermediate host: Pig cattle

Length : 2-4 m 4-8 m

No. proglottids: 700-1000 1000-2000

Scolex : 4 suckers 4 suckers but

with hooklets no hooklets

Taenia solium Taenia saginata

Gravid proglottid: 3-13 branches 13-30

branches

Larval stage (Cysticercus)

Taenia solium Taenia saginata

(Cysticercus cellulose) (Cysticercus bovis)

Scolex with hooklets no hooklets on Scolex

found in pig and man only found in cattle

Echinococcus granulosusDog tape worm

Echinococcus granulosusDog tape worm Habitat: adult: Small intestine in Dogs Larvae (Hydatid cyst): in Liver, Lung, brain in Intermediate host Definitive host : Dogs and other canines.Intermediate host: Sheep, cattle, etc, and other

herbivores. Accidentally Human. Disease: Unilocular Hydatid disease.

Morphology:3-8 mm in length.Scolex with Four suckers.Neck.Immature segment.Mature segment.Gravid segment.

Ova: Shape Round to OvalEmbryonated ( Hexacanth embryo inside)Radially striated egg shell.Onchosphere: six-hooked embryo inside the

egg.

Hydatid cysts in the Liver

Hydatid Cyst: • At maturity, the cyst wall contains 2 layers:1- laminated, noncellular outer tegument called the ectocyst,2- inner, germinal epithelium that produces the protoscolices called the endocyst• Brood capsules attached to the germinal epithelium by the stalk, extend into the fluid filled cavity of the cyst•Each brood capsule contains 10-30 protoscolices• If a cyst ruptures within a host, each liberated protoscolex can produce a daughter cyst

Protoscolices(hydatid sand)From hydatid cyst

Types of Hydatid Cyst

2- Fertile cyst

1-Sterile cyst

Pathology:Some people may have cysts in their bodies 5-

20 years without experiencing symptoms, or may never experience symptoms.

A. Mechanical1. Growing hydatid cyst lodged in the vital

organs likeliver, lungs, brain, heart interferes with the

functions of the organs2. Infection may become fatal due to growing

cyst which can cause obstruction to the organ

B. ToxicRupture of the cyst may produce allergic.

A figure showing a surgery procedure to remove hydatid cyst from a human patient

A hydatid cyst in the cranium of a child (the ruler at the top measures 6 inches long, and the child's brain is below the hydatid cyst).  This infection resulted in the child's death.

Diagnosis:

The diagnosis of Hydatidosis relies mainly on finding cysts by:

CT scan, X- Ray Serological tests.

Treatment:

Surgery is the most common form of treatment for Hydatid cysts. After surgery, medication may be necessary to keep the cyst from recurring.

The drug of choice is Albendazole, mebendazol

Prevention and Control

1- Personal hygiene2- Prevent dogs from eating carcasses of sheep,

goat cattle,etc.3- c0ntrol of stray dogs.

Hymenolepis nanadwarf tapeworm

Hymenolepis nanaCommon name: The Dwarf-Tape-Worm, ---Nanos

= dwarfDisease: Hymenolepiasis.Habitat: Small intestineDefinitive host: Human, Mice,RatsInfective stage: 1- Eggs ( if it eaten directly by Definitive host).

2-Cysticercoid larvae from insects. Diagnostic stage: Eggs in feces.

Hosts:Definitive host

HumanMice Rats

Intermediate host (Optional):Fleas, Beetles

The only cestode that parasitizes humans without requiring an intermediate host.

Morphology:Morphology:

Adult worm 1-4.5 cm long and 0.5-1 mm wide Neck is long and slender They have 100-200 segments that are wider

then they are long Scolex also has four suckers and, rostellum

armed with a single circle of 20-30 hooks proglottids are much broader than long Male system has 3 spherical testes, and

female bi-lobed ovary

Hymenolepis nana adult:

Egg:Eggs generally measure between 30

to 47 microns in diameter.

They are round to oval, and should contain a six-hooked oncosphere.

They have polar filaments that lie between the eggshell and the oncosphere.

polar filaments

Pathology and Clinical disease:Pathology and Clinical disease:

Most cases are asymptomatic, but with heavy infection they may be:

1- abdominal pain, nausea, vomiting, diarrhea, and anemia.

2- nervous symptoms, including dizziness and irritability, can occur in children.

Diagnosis:Diagnosis:Ova found in the feces polar filaments