The diagnosis of malaria depends on demonstration of the parasite in the blood. Two types of blood films are useful in looking for and identifying the malaria parasite. The ‘Thin film’ and ‘Thick film’. It is recommended that both types of film be prepared on a single microscope glass slide.

The thick film is more reliable in looking for parasites, as large volumes of blood are examined under each microscope field. When scanty, parasites may be found about 20 times more rapidly in a thick slide than in a thin slide. The thin slide is more valuable for identifying the species of the parasite present.