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Medical  Parasitology  Lab Medical  Parasitology  Lab

Medical Parasitology Lab - PowerPoint Presentation

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Medical Parasitology Lab - PPT Presentation

Artifacts Definition Artifacts other things living or artificial present in the stool that are not parasites and could mislead the laboratory worker Note Artifacts not to be mistaken for cysts ID: 631232

stool cyst confused giardia cyst stool giardia confused lamblia yeast wet trophozoites granules cells oval trophozoite eggs small iodine granular mount structure

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Slide1

Medical Parasitology Lab

ArtifactsSlide2

Definition Artifacts:

other things, living or artificial, present in the stool that are not parasites and could mislead the laboratory

worker.

Note:

“Artifacts not to be mistaken for cysts”.Slide3

BlastocystisRound 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.Slide4

BlastocystisSlide5

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

.Slide6

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

cystSlide7

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

. Slide8

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 Slide9

Bacteria Slide10

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:

4

sporozoites

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

One large round granular cell.

Refractile

granules completely fill the interior. Slide11

Coccidia (cont.) Slide12

Coccidia (cont.) Slide13

Air bubblesSlide14

Oil droplet Slide15

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

cystSlide16

Plant fiber Slide17

Strongyloides stercoralis larvae Slide18

Misdiagnosis can lead to improper treatmentSlide19

Hair fiberSlide20

Plant cellMay confused with helminthes eggsSlide21
Slide22

Plant cell

Plant material in an iodine-stained concentrated wet mount of stool.

This material can be confused for a hookworm eggSlide23

Charcot-Leyden crystalsSlide24

Epithelial cellsSlide25

Macrophages Slide26

RBCsSlide27

Pollen grainsSlide28

Pollen grainsSlide29

Starch granules Slide30

Crystals Slide31

Non- parasitic structure found in stoolNon parasitic objects may be misidentified as parasites. The differentiation of the most common pseudoparasites is as follow:

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.

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. Slide32

Cont. Ova, their general shape, except for Entrobius

, is perfectly symmetrical, distinguishing them from various objects found in stools.

Trichuris

and

Taenia

ova may be confused with pollen grains.

Ascaris

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

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 usedSlide33

Fasciola ova resemble vegetable cells.Insect and may be found in stools as spurious infection. Mite eggs may be confused with hookworm eggs. Dipylidium caninum eggs sacs can look similar to vegetable cells.

Other structure found in stool are crystals, Charcot- Leyden are the breakdown products of

eosinophil

cells and may be present in stools or sputum.

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.

Cont.

Slide34

Intestinal Protozoa Raed Z. Ahmed, Medical Parasitology Lab.,2012

Giardia lambliaSlide35

Giardia lambliaIt is the most common flagellate of the intestinal tract that cause giardiasis, Traveler's diarrhea.

There is two diagnostic stages for Giardia lamblia :

Cyst

is oval measuring 11

14u

in length and 7 to 10 µm in width

with

4

nuclei and remnant flagella,

and it’s the infective

stage.

Trophozoite

is

described as having a 'tear-drop' shape and are 10 to 20 µm long and 5 to 10 µm wide. The trophozoites contain two nuclei, four pair of

flagella. (motility

by flagella).

Diagnosis:

Stool examination to see cyst stage, or trophozoite stage if the sample is fresh.Slide36

Life cycleSlide37

Giardia lamblia cystSlide38

Giardia lamblia cystSlide39

Giardia lamblia Trophozoite Slide40

Giardia lamblia Trophozoite