Laboratory diagnosis of malaria
Plasmodium spp.
Determination of Parasitemia
Determination of parasitemia can be done using both thick and thin smears.
Thick smears:
The number of parasites/µl of blood is determined by enumerating the number of parasites
in relation to the standard number of WBCs/µl (8000).
No. Parasites × (8000 ÷ No. WBCs counted)
= No. parasites per µL of blood
Thin smears:
The percent of infected RBCs is determined by enumerating the number of infected
RBCs in relation to the number of uninfected RBCs. A minimum of 500 RBCs total
should be counted.
(No. infected RBCs ÷ Total No. RBCs counted) × 100
= Percent Infected RBCs
Notes:
• Multiply-infected RBCs are counted as one.
• Gametocytes are not figured in calculations.
