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Home , Cestoda

المحاضرة التاسعة Parasitology

Cestodes (Tape ) common features of Class Cestoda

- Adult is flattened ribbon-like, without body cavity. - The body is composed of a head, neck and segmented strobilus - The head has suckers, and hooklets or sucking grooves. - The neck is the budding zone from which segments are formed - The strobilus consists of immature, mature and pregnant proglottides. - They are hermaphroditic. - There is a set of female and male reproductive organs in every mature proglottid. - Digestive tract is absent. Nutrition is absorbed by villi of body surface. Scientific classification Kingdom: Animalia Examples : Platyhelminthes solium ( tapeworm) - Cysticercus Class: Cestoda (beef tapeworm) latum (fish tapeworm) Order: granulosus (unilocular hydatid) Family: Echinococcus multilocularis (alveolar hydatid) Genus: Taenia nana (dwarf tapeworm) Members of the genus are responsible for Hymenolepis diminutia and in humans. There are more than 100 species recorded. Taeniasis: Geographic Distribution

Worldwide, depending on dietary habits, and quality of cattle and pork farming.

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المحاضرة التاسعة Parasitology

o Humans are subject to by several species of tapeworms if they eat underprepared meat such as pork (), beef (T. saginata).

General Structure of Taenia

They are morphologically characterized by a ribbon-like body composed of a series of segments called proglottids; hence the name Taenia). Flat, segmented body with various length (several mm ~ several meters)

 Head region (scolex) : contains suckers and hooks used to attach to a organism. It is the zone of proliferation - Undifferentiated area behind the scolex (neck region)  Strobila - Chain of segments (proglottids). The chain of proglottids is called the strobila, and may be composed of over 1.000 proglottids. T.saginata may measure 9 m, whereas T.solium may reach 6 m. Proglottids are: - Immature proglottids - developing reproductive - Mature proglottids: mature reproductive organs. - Gravid proglottids: contain eggs in the uterus.

Taenia saginata (Hookless tapeworm) Taenia solium (Hook tapeworm)

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المحاضرة التاسعة Parasitology

The biological differences between T. solium and T. saginata ______Adult T. solium T. saginata ______length 2-4 meters 4-8 meters scolex 1mm in diameter with 2mm in diameter, with 4 suckers and hooklets 4 suckers but no hooklets Number of segment 700 to 1000 1000 to 2000 Mature proglottid 3 lobes of ovary 2 lobes of ovary Gravid proglottid 7-13 uterine lateral 15-30 uterine lateral branches on one side branches on one side Number of gravid usually several segments usually single segment proglottid detached Mode of proglottids passively expelled actively migrate out of anus passing out Cysticercus scolex with hooklets no hooklets on scolex found in man and pig only found in cattle Disease caused in man taeniasis and cysticercosis taeniasis

The life cycle

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المحاضرة التاسعة Parasitology

Pathogenesis and Clinical Manifestations

1. Taeniasis: It is caused by the adult residing in small intestine of the man. The adult irritates the small intestine causing discomforts, such as abdominal pain, anorexia, chronic indigestion, diarrhea, emaciation, eosinophilia and etc. The patient is usually no obvious symptom, only complaining passing proglottides.

2. Cysticercosis: It is caused by the cysticerci living in human tissues. The manifestations vary with the number of cysticerci and the tissues and organs involved. Cysticercosis is divided into three types.

(1) Subcutaneous type:

The subcutaneous nodules are usually found in head, limbs, neck, abdomen

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المحاضرة التاسعة Parasitology and back. They are movable and painless.

(2) Ocular type:

The cysticercus is usually found in the vitreous body or subretina. Visual disturbance often occurs. The died body of worm may provokes local inflammation causing blindness.

(3) Brain type:

The symptoms are related to the site of . The patients may manifest headache, nausea, vomiting, epilepsy, paralysis, weakness in limbs, diplopia, dizziness, mental disorder. Epilepsy is the most frequent symptoms of brain cysticercosis.

Diagnosis

1.Taeniasis: Confirmative diagnosis of taeniasis is made by finding gravid proglottides or egg in stool.

2. Cysticercosis: Biopsy of subcutaneous nodules, X-ray ,CT 0r MR are used for the diagnosis 3. Immunological tests are for reference only.

Prevention

- Health education - Avoid eating raw bean-pork. - Avoid pigs eating human stool. - Sanitary inspection of slaughter and sanitary disposal of night soil.

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