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Phylum: Platyhelminthes (Flatworms)

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Presentation on theme: "Phylum: Platyhelminthes (Flatworms)"— Presentation transcript:

1 Phylum: Platyhelminthes (Flatworms)
1-Cestoda (tape worms). 2-Trematoda (flukes). Cestoda (tape worms) A) Intestinal adult tapeworms. B) Extra-intestinal larval tapeworms.

2 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

3 1- The size 3mm – 10 m.

4 General Morphology The body of the typical cestode consists of 3 distinct regions: scolex neck strobila

5 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

6 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

7 Neck The neck is an unsegmented, poorly differentiated region immediately posterior to the scolex short measuring 5 to 10 mm in length

8 The 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

9 mature segment contain testes and ovary

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

11 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.

12 Classification of Cestoda

13 Intestinal adult tapeworms.
Taenia solium Taenia saginata Taenia multicepsis Hymenolepis nana Hymenolepis diminuta Dipylidium caninum Diphyllobothrium latum Extra-intestinal larval tapeworms Echinococcus granulosus Echinococcus multilocularis

14 Taenia solium (pork Tapeworm)

15 Taenia solium Common 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.

16 Taenia solium Adult worm 1- 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.

17 Proglottids Numbers : 700 to 1000 proglottids Composed of:
1- Immature proglottid 2- Mature proglottid: nearly square containing full set of functioning male and female reproductive organs 3- Gravid proglottid longer than broader consists: gravid uterus with 3 to 13 lateral uterine branches arranged.

18 Mature proglottid Gravid proglottid

19 Egg Shape – spherical Size: 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 `

20 Larval stage or bladder worm
also called Cysticercus cellulosae measurement – 5 to 10 mm in length and 5 mm in diameter scolex hooks suckers.



23 EPIDEMIOLOGY T. solium infection
Human infected (raw or undercooked pork) Man is the only definitive host and the pig appears to be the only intermediate host Man become the intermediate host Can be caused by: ingestion of eggs from contaminated food or water by internal autoinfection when the eggs are carried by reverse peristalsis back to the duodenum or stomach

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

25 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

26 Symptoms depend on location and number of larva

27 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.

28 Taenia saginata Beef Tapeworm.

29 Taenia saginata Common 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.

30 Taenia solium Taenia saginata Intermediate host: Pig cattle
Length : m m No. proglottids: Scolex : suckers suckers but with hooklets no hooklets

31 Taenia solium Taenia saginata Gravid proglottid: 3-13 branches 13-30 branches

32 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


34 Echinococcus granulosus
Dog tape worm

35 Echinococcus granulosus Dog 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.

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

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


39 Hydatid cysts in the Liver

40 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 protoscolices If a cyst ruptures within a host, each liberated protoscolex can produce a daughter cyst Protoscolices(hydatid sand) From hydatid cyst


42 Types of Hydatid Cyst 1-Sterile cyst 2- Fertile cyst

43 1. Growing hydatid cyst lodged in the vital organs like
Pathology: Some people may have cysts in their bodies 5-20 years without experiencing symptoms, or may never experience symptoms. A. Mechanical 1. Growing hydatid cyst lodged in the vital organs like liver, lungs, brain, heart interferes with the functions of the organs 2. Infection may become fatal due to growing cyst which can cause obstruction to the organ B. Toxic Rupture of the cyst may produce allergic.

44 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.

45 Diagnosis: The diagnosis of Hydatidosis relies mainly on finding cysts by: CT scan, X- Ray Serological tests.

46 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

47 Prevention and Control
1- Personal hygiene 2- Prevent dogs from eating carcasses of sheep, goat cattle,etc. 3- c0ntrol of stray dogs.

48 Hymenolepis nana dwarf tapeworm

49 Hymenolepis nana Common name: The Dwarf-Tape-Worm, ---Nanos = dwarf
Disease: Hymenolepiasis. Habitat: Small intestine Definitive host: Human, Mice,Rats Infective stage: 1- Eggs ( if it eaten directly by Definitive host). 2-Cysticercoid larvae from insects. Diagnostic stage: Eggs in feces. Hymenolepis nana

50 Hosts: Definitive host Intermediate host (Optional): Fleas, Beetles
Human Mice Rats Intermediate host (Optional): Fleas, Beetles The only cestode that parasitizes humans without requiring an intermediate host.

51 Morphology: Adult worm 1-4.5 cm long and 0.5-1 mm wide
Neck is long and slender They have segments that are wider then they are long Scolex also has four suckers and, rostellum armed with a single circle of hooks proglottids are much broader than long Male system has 3 spherical testes, and female bi-lobed ovary

52 Hymenolepis nana adult:

53 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

54 Hymenolepis nana life cycle2


56 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: Ova found in the feces polar filaments

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