Question (I)                                                                       (Total 10 marks)

(1) a- Taenia solium and Hymenolepis nana                     (2 marks)

b- Cysticercus cellulosae and cysticercoid nana.               (2 marks)

c- Pathogenesis of H.nana → Light infection gives rise to no manifestation.

Heavy infection especially in children leads to abdominal pain, loss of appetite, diarrhea or vomiting. Nervous manifestations as dizziness, insomnia and convulsions may occur due to absorption of toxic byproducts of the worm.                                                 (2 marks)

 

Treatment → Praziquantel is the drug of choice. Treatment should be repeated after 10 days due to liberation of cysticercoid from submucosa into the intestinal lumen.

Treatment of all members of the family at the same time, as the eggs are immediately infective. (2 marks)

 

(2) a- Eating undercooked meat: T.solium, Taenia saginata                        (1 mark)

b- Playing with dogs: Hydatid cyst, Dipylidium caninum                              (1 mark)

 

Question (II)                                                                    (Total 5 marks)

Diagnosis of hydatid disease:

 

· Clinically: By the presence of a slowly growing cystic tumor and history of close contact with dogs.

· Imaging techniques:

a. X-ray: especially in pulmonary cysts and calcified cysts:

i. Round solitary or multiple sharply contoured cysts of 1-5 cm in diameter.

ii. Internal daughter cysts give a car wheel appearance.

iii. Thin crescent or ring shape calcification.

b. Computerized tomography (CT) and Ultrasonography to detect uncalcified cysts and of value in the following up of treated cases.

· Laboratory diagnosis:

1. Aspiration cytology →using trichrome staining of the filtered aspirate to show acid fast hooklets. This procedure is risky and may cause transplantation of the germinal layer and formation of new cysts or anaphylactic shock.
2. Finding hydatid material →after surgical removal of the cyst or finding hydatid fragments from a ruptured cyst in the sputum or urine.
3. Serological tests as IHA or ELISA and Immunoelectrophoresis to detect antigen 5 or arc 5

4. Molecular diagnosis by DNA analysis and PCR.
5. Intradermal test of Casoni was used for a long time in diagnosis but it is not preferred because it may give allergic reactions.

Question (III)                                                                  (Total 10 marks)

(1) a- Taenia saginata                                                (2 marks)

b- Diagnostic stage: Taenia eggs or gravid segments + drawing

Infective stage: Cysticercus bovis + drawing                 (2 marks)

 

(2) a- It is the human infection with the larva stage of cestodes as Hydatid cyst (2 marks)

b- It is the breaking of the uterus into cysts each contains groups of eggs as in Dipylidium caninum                                                                                (2 marks)

c- It is the infective stage of Taenia saginata. It is oval , whitish vesicle, 10×5 cm in size, lined by germinal layer from which an invaginated unarmed scolex develops. It is filled with fluid and surrounded by fibrous tissue layer.                                 (2 marks)