Parasitology 2009
1.a 40 years old man hunting several month in central Africa, localized inflammed area on the dorsum of his left hand. Complain of remittent fever, headache, and anorexia. Enlargement of spleen and cervical lymph nodes.
a)Most possible diagnosis.
-African trypanosomiasis (African sleeping sickness)T. brucei rhodesiense
b)How this condition is acquired.
-Through bite of Glossina fly that introduced infective stage metacyctic trypomastigote into the patients blood.
c)What would the aspirate from the lymph nodes reveals.
-trypomastigote stage
d)Drug of choice of this diseases
-for haemolytic phase :suramine & pentamidine
-if there is CNS involvement, use melarsoprol, insya Allah kheir
e)Prognosis of that condition.
-good as it is not reach the terminal stages yet which is involvement of CNS and also CSF
2. A young female patient , inflammation of the eye, she used a contact lens, reveal severe keratitis. Scraping from the lesion of the cornea revealed a trophic parasite with spiky pseudopodia.
a)What is that parasite.
-Acanthamoeba
b)What is the infective stage.
-both trophozoite and cysts.
c)How was the infection is acquired.
-through entry of the trophozoites or cystic stages by inhalation of dust or water
-through broken skin, cornea, and genito-urinary tract.
d)Other organs commonly affected by this organism.
-CNS (granulomatous amoebic meningoencephalitis)
-skin (ulcer)
e)Treatment of the ocular lesion
-propamidine
3.In a form of differentiation.
(a) Oocyst of Cryptosporidia and Isospora belli
| Oocyst of Cryptosporidia | Oocyst of Isospora belli |
| -contains four naked sporozoites | -contains two mature sporocysts, each with four sporozoites |
| -thinned wall oocysts for internal autoinfection -thicked wall oocysts for external autoinfection | -maturation of oocysts occur outside the body |
(b) True and pseudocysts of Toxoplasma gondii
| True cysts | Pseudocysts |
| -contains of bradyzoites | -contains tachyzoites |
| -occur after acute condition subsides and as immunity of the host develops | -occur after repeated division (endodyogeny) |
(c) Intracellular & extracellular parasite that can be seen in a blood film as regards diagnostic morphology.
| Extracellular parasite (Trypanosoma) | Intracellular parasite (Malaria) |
(d) Two parasites affecting CNS as regard mode of infection and diagnostic stage.
| Naegleria fowleri | Acanthamoeba |
| -during swimming or bathing in contaminated water | -through entry of the trophic or cystic forms by inhalation of dust or water |
| -amoeboid form of trophozoite | -both trophozoite and cyst |
(e) Hepatic and erythrocytic Plasmodium schizonts.
| Hepatic Plasmodium schizonts | Erythrocytic Plasmodium schizonts |
| -inside the hepatic cells | -inside the red blood cells |
| -contains thousands of merozoites | -undergo repeated schizogonic cycle |
4. Give reason.
(a) Absence of trophozoites and schizonts from the peripheral blood of a patient infected with Plasmodium falciparum.
-Because they form a knobs, stick to the intima of the capillaries.
(b) In visceral Leishmaniasis, Leshmanin test become positive only after recovery.
-Because during the active course of the disease, the cellular immunity which is responsible for fighting this disease (T-cell) are depressed.
(c) In diagnosis of congenital toxoplasmosis, positive IgG is not a value and diagnosis should depend on positive IgM.
-Positive IgG have no significance because it is most probably passively tranferred from the mother.
-Positive IgM is more significance since it cannot pass through the placental barrier due to its high molecular weight thus its presence denotes that it is manufactured by the infant itself indicating active infection.
(d) Malabsorption syndrome can occur in giardiasis.
-It is due to blockage of the mucosal cells by the attachment of the numerous Giardia lamblia organisms by their sucking discs of the mucous membrane.
-It is also due to inflammation of the epithelial cells hindering their absorptive function.
(e) For diagnosis of a wet sore biopsy should be taken from the edge of the ulcer.
-To get the postive sample which is to detect the amostigote form from the smear.
-Smear from the floor of the ulcer are usually negative due to secondary infection.
Parasitology 2010
1.A young woman, fatty diarrhea and flatulence. Her appetite had remained quite good but she had lost 5kg and her energy was decreased. On stool examination, an infective agent was found.
(a) Most possible diagnosis.
-Giardiasis (Giardia lamblia)
(b) How this condition is acquired.
-ingestion of contaminated food or drink containing the infective stage which is cysts.
-direct infection form man to man
-external autoinfection
-mechanical transmission by houseflies
(c) What does stool examination reveal, describe the stage found.
-diarrhoeic stool reveal vegetative form (diagnostic stage)
-well formed stool reveal cysts form (both diagnostic and infective stage)
(d) Mechanism of fatty diarrhea
-It is due to blockage of the mucosal cells by the attachment of the numerous Giardia lamblia organisms by their sucking discs of the mucous membrane.
-It is also due to inflammation of the epithelial cells hindering their absorptive function.
2. A 3 year old child living in El-Agamy, he has high remittent fever, dysentry which does not respond to antipyretics and intestinal antiseptics. On examination, there were enlarged spleen, liver, and generalized lymphadenopathy. There is anemia, leucopenia, and thrombocytopenia. Stool examination was negative for parasites.
(a) Most possible diagnosis.
-visceral leishmaniasis
(b) How to confirm the diagnosis.
-based on history and clinical picture (intermittent fever, enlarge LN,spleen, liver and anemia)
-take biopsy from bone marrow, spleen, LN (reveal amastigote)
-iliac crest puncture is most suitable for children
-immunological method :ELISA, IFAT
-formol gel test
(c) Pathogenesis of dysentry.
- Necrosis of the epithelial lining of large intestine, erosion into the deeper tissue forming the ulcer.
-The mucosa in between the ulcer is healthy.
-Blood and mucous will pass in the stool.
(d) Treatment of this case.
-Miltefosine
3. In the table form, differentiate between
(a) Two protozoa causing eye lesion as regard infective stage and one diagnostic test.
| Toxoplasma Gondii | Acanthamoeba |
| -pseudocyst/cyst/mature oocyst | -both trophozoite and cyst |
| -immunological method (ELISA,IFAT,IHAT)
| -scraping from the lesions -culture seeded with Escherichia coli |
(b) Dry and wet sore as regard the causative parasite and lesion description.
| Dry sore | Wet sore |
| -Leishmania tropica | -Leishmania major |
| -small papule or nodule, heal with or without ulceration | -small itchy papule, initially are dry and lastly become wet |
(c) Parasitic stage of P.vivex and P.falciparum in the blood film.
parasitic stages of P.vivax,ade kesemua stages. bukan 2 shj mcm P.falciparum. enumerate sume but describe 2 stages yg sme shj iaitu ring & gametocyte.|
| P.vivex | P.falciparum |
| Ring stage | -Fills 1/3 of RBC | -very small, fills 1/6 RBC -multiple infection |
| Gametocytes | -spherical, compact fill the RBC. -host cell is enlarged with Schuffner’s dots | -cresent or banana-shaped appear in peripheral blood |
4. Give reasons.
(a) Relapse does not occur in malaria caused by blood transfusion.
-In this condition, the srythrocytic stages are passed from infected blood to the recipient initiating immediately erythrocyte cycle, without passing through the hepatic cycle.
(b) Dilaxonide furoate is the drug of choice for treatment of amoebic carrier.
-Its is the luminal amoebicides that acting primarily on organisms in the colonic lumen mainly cysts passers.
(c) Control of sleeping sickness in East Africa is much more difficult than in West Africa.
-Because of the extreme virulence of the organisms, patients die before the sleeping sickness stage is reached.
-Although the CNS is involved early, death usually occurs less than a year in untreated person.
-control depends on reservoirs hosts
