There are two main techniques for visualizing malarial parasites in the blood:
The thick film (thick drop preparation) is not actually a film: a drop of blood is applied to a slide, spread to cover a circular area of about 1.5 cm in diameter; and is allowed to dry for 24 hours. The slide is then covered with distilled water, and later with diluted Giemsa’s solution, which will cause the lysis of red cells. After 5 min. the solution is poured off, and again the slide is covered with Giemsa’s solution diluted 1:20 (as for regular blood smears), and incubated for 30 min. The further procedure is similar to the procedure for normal blood smears. If malarial parasites are present in blood cells, they will become visible.