A search for malarial organisms and trypanosomes should be completed using oil immersion (at least 300 fields) - The thick blood film is prepared by spreading a few drops of blood (using a circular motion) over an area approximately 2 cm in diameter. - If whole blood is used: examiner should continue stirring about 30 seconds to prevent the formation of fibrin strands. - The blood films must be laked before or during staining (rupture of all RBCs); the only structures that are left on the blood film are white blood cells, platelets, and parasites. - The disadvantages are that the red cells are lysed (dehemoglobinized) and the morphology of the parasites is distorted, so that species identification becomes difficult. - The WBCs on the stained blood film serve as the quality control - Reporting (Paniker)