The direct blood smear is used to determine the presence of which parasite form?

• A. RBC morphology
• B. Type of parasite
• C. Presence of microfilariae
• D. Platelet count

Answer: (C)

Direct blood smear is used to quickly look for circulating parasite forms that are visible as living, moving organisms in fresh blood. The classic use is to detect microfilariae, the larval stages of filarial worms, which can be seen directly in a smear of peripheral blood, especially when collected at times of day when they are present in the blood. RBC morphology and platelet counts are determined through other testing methods and stained smears or automated counting, while identifying the exact parasite type often requires additional staining and morphologic criteria. So the direct smear’s purpose is to confirm the presence of microfilariae.