Parasitology – Important Information to Remember

I. Blood Smear Technique

1. Two Methods of Blood Smear Preparation:

– Thin blood smear:

– Advantages: Easy to observe the morphology of parasites, easy to identify structural characteristics.

– Disadvantages: Time-consuming, only a small amount of parasites can be observed in one smear.

– Thick blood smear:

– Advantages: Observation of many parasites in one smear, time-saving.

– Disadvantages: Difficult to identify parasites due to the rupture of red blood cells, requires skilled technicians.

2. Blood Smear Staining Methods:

– Pappenheim staining method:

– Uses May-Grünwald and Giemsa stains.

– Used for thin blood smears.

– May-Grünwald stain:

– Fixes the specimen due to the presence of methyl alcohol.

– Stains cytoplasm, granules of neutrophils, basophils, and eosinophils.

– Giemsa stain:

– Stains the nucleus and blue-staining granules of large lymphocytes.

– Giemsa staining method:

– Uses Giemsa stain.

– Used for thick blood smears.

– Giemsa stain:

– Stains the nucleus and blue-staining granules of large lymphocytes.

3. Note:

– Avoid drying the blood smear, as it will lead to concentric rings.

– Use methyl alcohol to fix the blood drop.

– The buffer solution (pH 6.8-7.2) helps to decolorize the hemoglobin in thick blood smears, making it easier to observe parasites.

– Use cedar oil when observing the specimen under a 100x objective to increase resolution and provide clearer images.

II. Malaria Parasites

1. Distinguishing between mature trophozoites and gametocytes of Plasmodium vivax:

– Mature trophozoites: Amoeboid shape, containing Schuffner’s dots (brownish-red granules).

– Gametocytes: Round shape, with a dense, elongated or round nucleus.

2. Describing the young trophozoite of Plasmodium malariae:

– Ring-shaped.

– Cytoplasm thicker compared to P. falciparum, may have a “bird-eye” form.

3. Describing and distinguishing young trophozoites of Plasmodium falciparum and P. vivax:

– Plasmodium falciparum:

– Ring-shaped.

– Vacuole is clearly visible.

– Thin cytoplasm with 1-2 nuclei (multiple infections).

– Plasmodium vivax:

– Ring-shaped.

– Vacuole is not clearly visible.

– Thicker cytoplasm with 1 nucleus (single infection).

4. Describing gametocytes of Plasmodium falciparum:

– Male gametocyte:

– Cigar-shaped.

– Pinkish-purple or dark purple cytoplasm.

– Scattered nuclei.

– Hematin pigment distributed unevenly.

– Female gametocyte:

– Banana-shaped or sickle-shaped.

– Dense cytoplasm and nucleus.

– Hematin pigment concentrated densely around the nucleus.

5. Which method of blood smear preparation is better for identifying malaria parasites?

– Easier to observe with thin blood smears.

6. Advantages and disadvantages of the thick blood smear method:

– Advantages:

– Observation of many parasites simultaneously due to the use of a large amount of blood.

– More time-efficient.

– Disadvantages:

– Difficult to identify parasites due to the rupture of red blood cells.

– Requires skilled technicians.

7. Advantages and disadvantages of the thin blood smear method:

– Advantages:

– Easy to identify and observe parasites due to clear, beautiful, and typical morphology.

– Intact red blood cells.

– Disadvantages:

– Time-consuming.

– Only a small amount of parasites can be observed.

8. Advantages and disadvantages of the direct microscopy method for detecting malaria parasites:

– Advantages:

– Accurate observation of morphology, characteristics of parasites, and parasite density.

– Disadvantages:

– Time-consuming.

– Highly dependent on the technician’s skills.

9. Advantages and disadvantages of the rapid diagnostic test (RDT) for detecting malaria parasites:

– Advantages:

– Quick results.

– Can test many people at the same time, saving time.

– Disadvantages:

– Low accuracy.

– Does not determine parasite density.

10. Why is it necessary to evaluate parasite density when performing malaria parasite tests?

– To determine the current status of parasite infection.

– To evaluate the effectiveness of antimalarial drugs.

11. What objectives are used to observe malaria parasite specimens?

– 10x, 40x, and 100x.

12. How to use the 10x and 40x objectives:

– Bring the objective into position.

– Turn the light adjustment knob about 2/3 of a turn.

– Lower the condenser and close the diaphragm completely. Open the diaphragm slightly if using the 40x objective.

– Use the coarse focus knob until the field of view is visible.

13. How to use the 100x objective:

– Center the specimen in the field of view.

– Place a drop of cedar oil on the slide and immerse the objective tip into the oil.

– Raise the condenser to its maximum height, open the diaphragm completely, and use the fine focus knob to adjust until the image is clear.

III. Intestinal Parasites

1. What should be done with freshly collected stool samples?

– Place them in F2AM, PVA, or SAF preservative solution.

2. Where are amoebae found?

– In mucus-filled stools containing blood.

3. Formula for saturated salt solution:

– 250g salt in 750ml water.

4. What objectives are used to observe stool samples?

– 10x and 40x.

5. What is used to disperse stool samples?

– 0.85% saline solution or 5% Lugol’s solution.

6. Why are only cyst forms observed during examination and not trophozoites?

– Trophozoites are not present in stool.

– Trophozoites are only found in the stool of people with acute diarrhea and only if the stool is examined within 30 minutes.

7. Distinguishing between the sucker and the buccal sucker:

– There is only one sucker and two buccal suckers.

8. Distinguishing between the terminal segment and the respiratory tube of the larva:

– The terminal segment has hairs.

Note:

– When observing, pay attention to the shape, size, and structure of parasites, especially the characteristic features of each type of parasite.

– Use personal protective equipment such as gloves and masks when working with biological samples.

– Strictly follow biosafety regulations in the laboratory.

– Diagnosis of parasites should be performed by qualified healthcare professionals.

In addition to the information provided, studying parasites requires in-depth knowledge of each specific type of parasite, diagnostic methods, treatment, prevention, and related knowledge. You can refer to specialized materials or search for information from reliable sources.

Remember, the information provided here is general and should not replace professional medical advice. Always consult with a qualified healthcare professional for diagnosis and treatment.