ParasitologyParasitology

Helminthology

Platyhelminthes(Flat worms)

Nematohelminthes (Round worms)

Trematoda (Flukes)

Ceastoda(Tape worms)

Nematoda

Define:Disease:-

Class Class CestodaCestoda

(Tape Worms)(Tape Worms)

Cestoda

D.HI.S.

I.H. D.S

Taenia solium & Taenia saginata

In this course we study:

Hymenolepis nana & Hymenolepis diminuta

Echinococcus granulosus.

Hymenolepis Hymenolepis nana nana

& & Hymenolepis Hymenolepis

diminutadiminuta

Name:Name: Hymenolepis nanaHymenolepis nana Hymenolepis Hymenolepis diminutadiminuta

Definition:Definition: Dwarf tapeworm Rat tapewormDistributionDistribution::

Cosmopolitan

Disease:Disease: HymenolepiasisPathogeniciPathogenicity:ty:

•Usually asymptomatic.• In case of severe, heavy infection there may be abdominal pain, enteritis and diarrhoea.

• Anaemia & nervous symptoms can occur in children.

• Generally there is no effect on the host.

Hymenolepis Hymenolepis nananana

Hymenolepis Hymenolepis diminutadiminuta

Habitat:Habitat:

Definitive Definitive host:host:

IntermediatIntermediate host:e host:

Diagnostic Diagnostic stage:stage:

Hymenolepis Hymenolepis nananana

Hymenolepis Hymenolepis diminutadiminuta

Infective Infective stagestage::

Mode of Mode of infectioninfection::

TreatmentTreatment::

Adult worm of Hymenolepis nana

• Adult worm is small thread like, 2-3 cm in length.

• It consist of over 100 segments all of which are broader than long.

* Uterine branches is hardly visible. *Each segment 1 mm wide.

Gravid segment of Hymenolepis diminuta

) 1 (Mature segment (2) Gravid segmentof Hymenolepis diminuta

Hymenolepis nana Scolex

• The scolex has four suckers which are not visible in this plane of focus (two are marked by *), and an armed rostellum that is clearly visible. 

• The scolex has four suckers. • (two are marked by the *), but no hooks [absence of an armed rostellum].

Hymenolepis diminuta Scolex

EchinococcuEchinococcu

s granulosuss granulosus

NameName:: Echinococcus granulosusEchinococcus granulosus

DefinitionDefinition:: Dog tape worm , or hydated tape worm.

DistributionDistribution:: In the Mediterranean region

DiseaseDisease:: Echinococcosis , unilocular hydated cyst.

MorphologyMorphology:: • Scolex: with 4 suckers and a double hook crowned rostellum.• The rest of the body consists of 3 proglottides giving the worm a length of 2.5-9 mm.

Echinococcus granulosus

Habitat:Habitat:

Definitive Definitive host:host:

IntermediatIntermediate host:e host:

Echinococcus granulosus

Diagnostic Diagnostic stagestage::

Infective Infective stagestage::

Mode of Mode of infectioninfection::

Echinococcus granulosus

TreatmentTreatment::

PreventionPrevention::

When the eggs of Echinococcus granulosus are ingested by the intermediate host, eggs hatch in small intestine giving the hooked embryo which penetrate intestinal mucosa and enters the blood circulation.

If the embryo escapes phagocytosis it resides in any tissue, lose its hooks and transforms to a cyst which is 10 mm in diameter. This process may take 5 months.

Echinococcosis , unilocular hydated cyst

The cyst is composed from an external laminated

hyaline membrane followed by a germinal layer.

The cyst is filled with a sterile fluid.

Brood capsules are found inside the cyst,

consisting of only germinal layer and

protoscoleces. Ruptured capsule give thousands of

protoscoleces at the bottom of the cyst, that is the

hydated sand.

Hydated cysts can occur in bones, lungs, liver,

brain or kidney.

Adjacent organs are affected due to presence of the

cyst beside the inflammatory reaction against it.

Cyst can cause blood vessels erosion and

haemorrhage.

Removal of the cysts must done with care; sever

allergic reactions or even dissemination of the

hydated sand in the rupture. Cyst rupture could

happen also in response to cough or muscle strain.

Adult worm of Echinococcus granulosus

It is the smallest cestode; composed only from 3 segments (proglottides).

Hydated sand