medical parasitology lab

Raed Z. Ahmed, Medical Parasitology Lab.,2012

BlastocystisBlastocystis


• Round or oval, sometimes with angular irregular edges, contain one large vacuole taking up almost the whole cell, the compressed cytoplasm forms a granular ring round it.

BlastocystisBlastocystis


Yeast Yeast


• Oval, often with buds, often contain eccentric cluster of 3-6 small granules.

• Some related forms of yeast are rectangular, with a very clear oval cytoplasm inside: arthrospores.

Yeast Yeast


Yeast in an iodine-stained concentrated wet mount of stool. Yeast in wet mount may be confused for Giardia lamblia cyst.

Yeast Giardia lamblia cyst

Leukocytes Leukocytes


• Round or slightly elongated, with an irregular outline.

• Contain refractile cytoplasm, clear and granular with tiny vacuoles.

• Nucleus indistinct, sometimes with a star- shaped false karyosome.

Pus Pus


• Pus can be seen by the naked eye as opaque, greyish streaks( not transparent like mucus).

• Under the microscope it appears as a mass of more or less degenerate leukocytes

Coccidia Coccidia


• These are protozoa that may be parasite of men without causing any significant pathogenic effects, or may be found in transit in stool following the consumption of infected foods.

• They appear in stool in a form resembling cyst called oocysts or sporocysts.

• An elongated oval, sometimes tapered at one pole.• There three types:

a. 4 sporozoites (small banana shaped rods), each containing a small round nucleus, sometimes a few large granules massed at one pole.

b. One large round granular cell.c. Refractile granules completely fill the interior.

Coccidia Coccidia (cont.) (cont.)


Oil droplet Oil droplet


Fungal spores Fungal spores


Fungal spore in a wet mount of stool. Such spores may be confused for the cysts of Entamoeba spp.

Fungal spore Entamoeba histolytica/dispar cyst

Plant fiber Plant fiber


Strongyloides stercoralis Strongyloides stercoralis larvaelarvae


Misdiagnosis can lead to improper treatment


Hair fiberHair fiber


Plant cellPlant cell


May confused with helminthes eggs

Plant cellPlant cell


• Plant material in an iodine-stained concentrated wet mount of stool.This material can be confused for a hookworm egg

Charcot-Leyden crystalsCharcot-Leyden crystals


Epithelial cellsEpithelial cells


Macrophages Macrophages


RBCsRBCs


Pollen grainsPollen grains


Starch granules Starch granules


Crystals Crystals



Non parasitic objects may be misidentified as parasites. The differentiation of the most common pseudoparasites is as follow:

1. Protozoan cyst: may be confused with air bubbles, fat globules or yeasts. – Iodine should be added to the wet preparation so that the internal

structure of the cyst is stained and identifiable.

2. Amoebic trophozoites: must be differentiated from non- pathogenic protozoan trophozoites and macrophages.– Trophozoites of Entamoeba histolytica/dispar must be motile and

hematophagus.

– Macrophages found in cases of intestinal amoebiasis are distinguishable from amoebic trophozoites by possessing a larger nucleus and, although they can haematophagus, they are only motile for a very short time. Their pseudopodia are small, blunt and granular.


3. Ova, their general shape, except for Entrobius, is perfectly symmetrical, distinguishing them from various objects found in stools.

4. Trichuris and Taenia ova may be confused with pollen grains.

5. Ascaris ova may be confused with vegetable cells, the latter having smooth, thick walls but irregular shape.

6. Strongyloides or hookworm larvae can be confused with hair or vegetable fibers. The latter are usually tapered at one end and the other being blunt and with no internal structure.– Free living nematode larvae may be found in concentrates if

contaminated water is used


7. Fasciola ova resemble vegetable cells.

8. Insect and may be found in stools as spurious infection. Mite eggs may be confused with hookworm eggs.

9. Dipylidium caninum eggs sacs can look similar to vegetable cells.

10. Other structure found in stool are crystals, Charcot- Leyden are the breakdown products of eosinophil cells and may be present in stools or sputum.

11. Starch granules are sometimes seen in stool. When undigested, they appear as concentric rings and stain blue with iodine, when partially digested, they stain red.

Entamoeba histolytica/ disparEntamoeba histolytica/ dispar

• E. histolytica inhabit large intestine and cause amoebic dysentery.

• There is two diagnostic stages for E. histolytica/ dispar:

1. Cyst is regular round measuring measure 10 – 20u in diameter with 4 nuclei, and it’s the infective stage.

2. Trophozoite is the motile form, measure 15-20u in diameter with large nucleus. (motility by pseudopodia).

• Diagnosis:

– Stool examination to see cyst stage, or trophozoite stage if the sample is fresh.


Life cycleLife cycle


http://upload.wikimedia.org/wikipedia/commons/a/a1/Entamoeba_histolytica_life_cycle-en.svg

Entamoeba histolytica/ disparEntamoeba histolytica/ dispar Cyst Cyst


Entamoeba histolytica/ disparEntamoeba histolytica/ dispar Trophozoite Trophozoite


medical parasitology lab

Documents

medical parasitology

yeast raed

coccidia raed

pus raed

macrophages raed

fungal spores raed

oil droplet raed

degenerate leukocytes