Malaria Parasite (MP) detection and counting under the microscope, including objective, principle, materials, procedure, formula, and an example calculation:


MP (Malaria Parasite) Detection & Parasitemia Count

1.  Objective

To detect and quantify the presence of malaria parasites in a patient’s blood using microscopy, and to estimate the level of parasitemia (number of parasites per µL of blood).

2.  Principle

Malaria parasites (e.g., Plasmodium falciparum, P. vivax) were detected by examining Giemsa-stained thick and thin blood smears under a microscope.

  • Thick smear: More sensitive – used for detection.

  • Thin smear: Used for species identification.

  • Parasite density was calculated by counting the number of parasites against 200 white blood cells (WBCs) or per 1,000 RBCs (less common).

3.  Materials

  • Patient’s capillary blood (finger prick)

  • Glass slides

  • Giemsa stain

  • Microscope

  • Immersion oil

  • Lancet, alcohol swab

  • Timer, gloves

4.  Procedure

  1. Prepared thick and thin smears on clean slides.

  2. Allowed the thick smear to air-dry completely (do not fix with methanol).

  3. Fixed thin smear with methanol.

  4. Stained with 10% Giemsa for 10 minutes.

  5. Rinsed, dried, and examined under 100x oil immersion.

  6. Counted number of malaria parasites per 200 WBCs in thick smear.

5.  Formula to Calculate Parasite Density

Parasites/µL of blood=(Number of parasites countedNumber of WBCs counted)×Actual WBC count per µL\text{Parasites/µL of blood} = \left( \frac{\text{Number of parasites counted}}{\text{Number of WBCs counted}} \right) \times \text{Actual WBC count per µL}

  • If WBC count is unknown, assume average WBC = 8,000 /µL

6.  Example Calculation

Given:

  • 80 parasites counted in thick smear

  • Counted over 200 WBCs

  • Patient’s WBC count: 7,500 /µL

Parasites/µL=(80200)×7,500=0.4×7,500=3,000 parasites/µL\text{Parasites/µL} = \left( \frac{80}{200} \right) \times 7,500 = 0.4 \times 7,500 = \boxed{3,000 \text{ parasites/µL}}

Interpretation:

  • <1,000/µL = Low parasitemia

  • 1,000–10,000/µL = Moderate

  • >10,000/µL = High parasitemia

  • >100,000/µL = Severe (especially for P. falciparum)

7.  Uses

  • Diagnosed and monitored malaria infection

  • Determined treatment success or failure

  • Differentiated Plasmodium species

8.  Conclusion

Microscopic counting of malaria parasites using a thick smear provided a quantitative estimate of parasitemia, which was critical in diagnosis and management of malaria, especially in endemic regions.


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